Clinical Practice Guidelines For The Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures – 2019 Update: Cosponsored By American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society For Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists*

Clinical Practice Guidelines For The Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures – 2019 Update: Cosponsored By American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society For Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists***These guidelines are endorsed by the American Society for Nutrition (ASN), American Society for Parenteral and Enteral Nutrition (ASPEN), International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO), International Society for the Perioperative Care of the Obese Patient (ISPCOP), and Obesity Action Coalition (OAC).By mutual agreement among the authors and editors of their respective journals, this work is being published jointly in Surgery for Obesity and Related Diseases, Obesity, and Endocrine Practice. © AACE 2019. DOI: 10.4158/GL-2019-0406Address reprint requests to publications@aace.com.Published as a Rapid Electronic Article in Press at http://www.endocrinepractice.org on November 4, 2019. DOI: 10.4158/GL-2019-0406.GLAmerican Association of Clinical Endocrinologists, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists medical guidelines for clinical practice are systematically developed statements to assist health-care professionals in medical decision-making for specific clinical conditions. Most of the content herein is based on clinical evidence. In areas of uncertainty, or when clarification is required, expert opinion and professional judgment were applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made considering local resources and individual patient circumstances.

      ABSTRACT

      Objective

      The development of these updated clinical practice guidelines (CPGs) was commissioned by the American Association of Clinical Endocrinologists (AACE), The Obesity Society, American Society of Metabolic and Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists Boards of Directors in adherence with the AACE 2017 protocol for standardized production of CPGs, algorithms, and checklists.

      Methods

      Each recommendation was evaluated and updated based on new evidence from 2013 to the present and subjective factors provided by experts.

      Results

      New or updated topics in this CPG include: contextualization in an adiposity-based chronic disease complications-centric model, nuance-based and algorithm/checklist-assisted clinical decision-making about procedure selection, novel bariatric procedures, enhanced recovery after bariatric surgery protocols, and logistical concerns (including cost factors) in the current health-care arena. There are 85 numbered recommendations that have updated supporting evidence, of which 61 are revised and 12 are new. Noting that there can be multiple recommendation statements within a single numbered recommendation, there are 31 (13%) Grade A, 42 (17%) Grade B, 72 (29%) Grade C, and 101 (41%) Grade D recommendations. There are 858 citations, of which 81 (9.4%) are evidence level (EL) 1 (highest), 562 (65.5%) are EL 2, 72 (8.4%) are EL 3, and 143 (16.7%) are EL 4 (lowest).

      Conclusion

      Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity. Clinical decision-making should be evidence based within the context of a chronic disease. A team approach to perioperative care is mandatory, with special attention to nutritional and metabolic issues. (Endocr Pract. 2019;25:1-75)

      Abbreviations:

      A1C
      hemoglobin A1c;
      AACE
      American Association of Clinical Endocrinologists;
      ABCD
      adiposity-based chronic disease;
      ACE
      American College of Endocrinology;
      ADA
      American Diabetes Association;
      AHI
      Apnea-Hypopnea Index;
      ASA
      American Society of Anesthesiologists;
      ASMBS
      American Society of Metabolic and Bariatric Surgery;
      BMI
      body mass index;
      BPD
      biliopancreatic diversion;
      BPD/DS
      biliopancreatic diversion with duodenal switch;
      CI
      confidence interval;
      CPAP
      continuous positive airway pressure;
      CPG
      clinical practice guideline;
      CRP
      C-reactive protein;
      CT
      computed tomography;
      CVD
      cardiovascular disease;
      DBCD
      dysglycemia-based chronic disease;
      DS
      duodenal switch;
      DVT
      deep venous thrombosis;
      DXA
      dualenergy X-ray absorptiometry;
      EFA
      essential fatty acid;
      EL
      evidence level;
      EN
      enteral nutrition;
      ERABS
      enhanced recovery after bariatric surgery;
      FDA
      U.S. Food and Drug Administration;
      G4GAC
      Guidelines for Guidelines, Algorithms, and Checklists;
      GERD
      gastroesophageal reflux disease;
      GI
      gastrointestinal;
      HCP
      health-care professional(s);
      HTN
      hypertension;
      ICU
      intensive care unit;
      IGB
      intragastric balloon(s);
      IV
      intravenous;
      LAGB
      laparoscopic adjustable gastric band;
      LAGBP
      laparoscopic adjustable gastric banded plication;
      LGP
      laparoscopic greater curvature (gastric) plication;
      LRYGB
      laparoscopic Roux-en-Y gastric bypass;
      LSG
      laparoscopic sleeve gastrectomy;
      MetS
      metabolic syndrome;
      NAFLD
      nonalcoholic fatty liver disease;
      NASH
      nonalcoholic steatohepatitis;
      NSAID
      nonsteroidal antiinflammatory drug;
      OA
      osteoarthritis;
      OAGB
      oneanastomosis gastric bypass;
      OMA
      Obesity Medicine Association;
      OR
      odds ratio;
      ORC
      obesity-related complication(s);
      OSA
      obstructive sleep apnea;
      PE
      pulmonary embolism;
      PN
      parenteral nutrition;
      PRM
      pulmonary recruitment maneuver;
      RCT
      randomized controlled trial;
      RD
      registered dietician;
      RDA
      recommended daily allowance;
      RYGB
      Roux-en-Y gastric bypass;
      SG
      sleeve gastrectomy;
      SIBO
      small intestinal bacterial overgrowth;
      TOS
      The Obesity Society;
      TSH
      thyroid-stimulating hormone;
      T1D
      type 1 diabetes;
      T2D
      type 2 diabetes;
      VTE
      venous thromboembolism;
      WE
      Wernicke encephalopathy;
      WHO
      World Health Organization

      LAY ABSTRACT

      Obesity is an officially recognized global disease and continues to be a risk factor for chronic medical conditions such as cardiovascular diseases, diabetes, chronic kidney disease, nonalcoholic fatty liver disease, metabolic syndrome, and many cancers. This updated guideline is based on an increased number and quality of the best available scientific studies to guide physicians in the clinical care of patients with obesity who undergo surgical and nonsurgical bariatric procedures. This guideline identifies patient candidates for bariatric procedures, discusses which types of bariatric procedures should be offered, outlines management of patients before procedures, and recommends how to optimize patient care during and after procedures. Since publication of the previous guideline in 2013, the role of bariatric surgery in the treatment of patients with type 2 diabetes has grown substantially. Studies have demonstrated that bariatric/metabolic surgery achieves superior improvements in glycemic control of patients with type 2 diabetes and obesity, compared with various medical and lifestyle interventions, and leads to substantial cost savings. Improved cardiovascular outcomes and quality of life have also been reported in patients undergoing bariatric surgery. New and emerging surgical and nonsurgical bariatric procedures are described. Criteria for bariatric procedures are better defined. This update includes checklists to assist health-care professionals achieve greater precision in clinical decision-making and discusses the importance of a team approach to patient care, with special attention on nutrition, metabolism, and interventions to improve recovery after bariatric surgery. Enhanced recovery after bariatric surgery procedures are discussed in detail. Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity.

      INTRODUCTION

      This 2019 clinical practice guideline (CPG) update provides revised clinical management recommendations that incorporate evidence from 2013 to the present, a period marked by a significant increase in the total number of publications on bariatric surgery, especially randomized controlled trials (RCTs), meta-analyses, and reviews (Table 1). In addition, this update requires reinterpretation of the utility and decision-making process within the context of an evolving obesity-care model, increasingly detailed management strategies and protocols, and the need for a more transparent tactical plan in a probing and scrutinizing health-care environment. New diagnostic terms, structured lifestyle approaches, pharmaceutical options, and surgical and nonsurgical procedures have reshaped the obesitycare space. A general overview of the clinical pathway for bariatric surgery is provided in Figure 1. Readers are advised to refer to earlier editions of this CPG for additional supporting evidence, including the basics of bariatric surgery mechanisms of actions, risks, and benefits.
      Table 1Increased PubMed Citations on Bariatric Surgery with Each Clinical Practice Guidelines Update
      The search term used was “bariatric surgery” on December 31, 2018. Standard PubMed filters were used with customized publication dates. Non-English figures were the difference of unfiltered amounts and the “English” language filter. Non-English percentages use “Total” publications as the denominator. Percentage change (% D) uses the figure at the previous publication date range as the denominator. Simple analysis shows that the greatest increase in total, RCT, meta-analysis, and reviews occurred since publication of the last AACE/ASMBS/TOS bariatric surgery CPG update in 2013 in bold (1). The number of guidelines and non-English publications on bariatric surgery has remained generally constant over the years.
      YearsNon-English (% total)RCT (% Δ)Meta-Analysis (% Δ)Review (% Δ)Guideline (% Δ)Total (% Δ)
      <2008975 (13)204201,148347,746
      2008-2012576 (8)201 (−0.01)46 (130)1,210 (5)40 (18)7,254 (−6)
      2013-2018605 (4)746 (271)218 (374)2,396 (98)44 (0.1)14,105 (94)
      All years2156 (7)1,1542844,75411829,105
      Abbreviation: RCT = randomized controlled trial.
      Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      a The search term used was “bariatric surgery” on December 31, 2018. Standard PubMed filters were used with customized publication dates. Non-English figures were the difference of unfiltered amounts and the “English” language filter. Non-English percentages use “Total” publications as the denominator. Percentage change (% D) uses the figure at the previous publication date range as the denominator. Simple analysis shows that the greatest increase in total, RCT, meta-analysis, and reviews occurred since publication of the last AACE/ASMBS/TOS bariatric surgery CPG update in 2013 in bold
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      . The number of guidelines and non-English publications on bariatric surgery has remained generally constant over the years.
      Fig. 1
      Fig. 1Bariatric procedure decision-making. BMI = body mass index; ERABS = enhanced recovery after bariatric surgery.

       Update on Obesity as a Disease and Clinical Assessment

      Since the publication of the 2013 American Association of Clinical Endocrinologists (AACE)/The Obesity Society (TOS)/American Society of Metabolic and Bariatric Surgery (ASMBS) bariatric surgery CPG (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ), obesity continues to be a major national and global health challenge, as well as a risk factor for an expanding set of chronic diseases, including cardiovascular disease (CVD), diabetes, chronic kidney disease, nonalcoholic fatty liver disease (NAFLD), metabolic syndrome (MetS), and many cancers, among other comorbid conditions. Obesity is now included among the global noncommunicable disease targets identified by the World Health Organization (WHO) (
      NCD Risk Factor Collaboration
      Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19.2 million participants.
      ,
      • Kontis V.
      • Mathers C.D.
      • Rehm J.
      • et al.
      Contribution of six risk factors to achieving the 25x25 non-communicable disease mortality reduction target: a modelling study.
      ,
      • WHO
      Global action plan for the prevention and control of noncommunicable diseases 2013-2020.
      ). In 2015, a total of 107.7 million children and 603.7 million adults had obesity worldwide (
      • Afshin A.
      • Forouzanfar M.H.
      • Reitsma M.B.
      • et al.
      Health Effects of Overweight and Obesity in 195 Countries over 25 Years.
      ). The prevalence of obesity in the United States is among the highest in the world. According to the National Health and Nutrition Examination Survey 2013-2016 dataset, 38.9% of U.S. adults and 18.5% of youth aged 2 to 19 years had obesity (
      • Ogden C.L.
      • Carroll M.D.
      • Fryar C.D.
      • Flegal K.M.
      Prevalence of Obesity Among Adults and Youth: United States.
      ,
      • Ogden C.L.
      • Carroll M.D.
      • Kit B.K.
      • Flegal K.M.
      Prevalence of childhood and adult obesity in the United States, 2011-2012.
      ). This translates into 93.3 million adults and 13.7 million children and youth, respectively. More women (40.8%) than men (36.5%) were obese, with non-Hispanic black women (55.9%) showing the highest rates of prevalence (
      • Ogden C.L.
      • Carroll M.D.
      • Fryar C.D.
      • Flegal K.M.
      Prevalence of Obesity Among Adults and Youth: United States.
      ,
      • Ogden C.L.
      • Carroll M.D.
      • Kit B.K.
      • Flegal K.M.
      Prevalence of childhood and adult obesity in the United States, 2011-2012.
      ). Although the prevalence of obesity has been steady among adults since 2011-2012, rates of prevalence in certain subpopulations continue to rise, particularly for those with severe (class III, body mass index [BMI] ≥40 kg/m2) obesity where overall age-adjusted rates of prevalence are 5.5% and 9.8% for men and women, respectively, and 16.8% for non-Hispanic women (
      • Flegal K.M.
      • Kruszon-Moran D.
      • Carroll M.D.
      • Fryar C.D.
      • Ogden C.L.
      Trends in obesity among adults in the united states, 2005 to 2014.
      ).
      The global burden of obesity is driven by the association between BMI and increased morbidity and mortality. Although BMI is simplistic (it is only an anthropometric calculation of height-for-weight; or more specifically, weight in kilograms [kg] divided by height in meters squared) and has been criticized as an insensitive marker of disease, it currently provides the most useful population-level measurement of overweight and obesity, and its utility as an estimate of risk has been validated in multiple large population studies across multiple continents. The j-shaped curve for BMI and mortality has recently been confirmed in a large meta-analysis (
      Global BMI Mortality Collaboration
      Body-mass index and allcause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents.
      ) and a systematic review (
      • Aune D.
      • Sen A.
      • Prasad M.
      • et al.
      BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants.
      ) that included 10.6 million and 30 million participants, respectively. These two studies confirm that both overweight and obesity increase the risk of all-cause mortality and should be prioritized on a population level.
      Based on the complexity of body-weight regulation, increased morbidity and mortality associated with obesity, and the substantial burden on public health, obesity was officially recognized as a disease by the American Medical Association in 2013 along with multiple other organizations, and most recently by the World Obesity Federation (
      • Bray G.A.
      • Kim K.K.
      • Wilding J.P.H.
      Obesity: a chronic relapsing progressive disease process. A position statement of the World Obesity Federation.
      ). Several guidelines for treatment of obesity have also been published as a resource for clinicians since 2013. Most notable are the American Heart Association /American College of Cardiology/TOS Guideline for the Management of Overweight and Obesity in Adults (
      • Jensen M.D.
      • Ryan D.H.
      • Apovian C.M.
      • et al.
      2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society.
      ), The AACE and the American College of Endocrinology (ACE) Clinical Practice Guidelines for Comprehensive Care of Patients with Obesity (
      • Garvey W.T.
      • Mechanick J.I.
      • Brett E.M.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology comprehensive clinical practice guidelines for medical care of patients with obesity.
      ), the Obesity Medicine Association (OMA) Obesity Management Algorithm (

      Bays HE, McCarthy W, Christensen S, et al. Obesity Algorithm eBook, presented by the Obesity Medicine Association. www.obesityalgorithm.org. Available at: https://obesitymedicine.org/obesity-algorithm/ Accessed July 24, 2019.

      ), and the Pharmacological Management of Obesity guidelines from the Endocrine Society (
      • Apovian C.M.
      • Aronne L.J.
      • Bessesen D.H.
      • et al.
      Pharmacological management of obesity: an Endocrine Society clinical practice guideline.
      ). In 2017, the American Gastroenterological Association (AGA) issued a Practice Guide on Obesity and Weight Management, Education, and Resources (POWER) that emphasized a comprehensive approach to assessment, treatment, and prevention (
      • Acosta A.
      • Streett S.
      • Kroh M.D.
      • et al.
      White Paper AGA: POWER - Practice guide on obesity and weight management, education, and resources.
      ). This AGA guideline is particularly important for the increasing number of gastroenterologists who are performing endoscopic procedures for the treatment of obesity that include placement of intragastric balloons, plications and suturing of the stomach, and insertion of a duodenal-jejunal bypass liner, among other emerging procedures (
      • Sullivan S.
      • Edmundowicz S.A.
      • Thompson C.C.
      Endoscopic bariatric and metabolic therapies: new and emerging technologies.
      ).
      In addition to these guidelines, efforts are also underway to develop more practical and useful assessments to identify patients who require increased medical attention for obesity-related conditions. Analogous to other staging systems commonly used for congestive heart failure or chronic kidney disease, the AACE/ACE obesity CPG proposes an obesity staging system that is based on ethnic-specific BMI cutoffs along with assessment for adiposity-related complications (
      • Garvey W.T.
      • Mechanick J.I.
      • Brett E.M.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology comprehensive clinical practice guidelines for medical care of patients with obesity.
      ). Stage 0 is assigned to individuals who have overweight or obesity by BMI classification but have no complications, whereas Stage 1 and 2 are defined as individuals who are overweight or obese by BMI classification and have one or more mild-moderate complications (Stage 1) or at least one severe complication (Stage 2). Building off this complications-centric approach to obesity care, AACE/ACE recently proposed a new diagnostic term for obesity using the abbreviation “ABCD,” which stands for adiposity-based chronic disease (
      • Mechanick J.I.
      • Hurley D.L.
      • Garvey W.T.
      Adiposity-based chronic disease as a new diagnositc term: the American Association of Clinical Endocrinologists and American College of Endocrinology position statement.
      ). A different functional staging system for obesity was proposed by Sharma and Kushner (
      • Sharma A.M.
      • Kushner R.F.
      A proposed clinical staging system for obesity.
      ). Using a risk-stratification construct, referred to as the “Edmonton Obesity Staging System” (EOSS), individuals with obesity are classified into five graded categories, based on their morbidity and health-risk profile along three domains: medical, functional, and behavioral. The staging system was shown to predict increased mortality in two large population cohorts (
      • Kuk J.L.
      • Ardern C.I.
      • Church T.S.
      • et al.
      Edmonton Obesity Staging System: association with weight history and mortality risk.
      ,
      • Padwal R.S.
      • Pajewski N.M.
      • Allison D.B.
      • Sharma A.M.
      Using the Edmonton obesity staging system to predict mortality in a population-representative cohort of people with overweight and obesity.
      ). The need to shift from BMI-to complications-centric decision-making has applications beyond the U.S.; for example, in China, acceptance levels for bariatric surgery are principally based on the need for and expectations of weight loss, rather than treatment of severe obesity-related complications (ORC) (
      • Liang H.
      • Liu Y.
      • Miao Y.
      • Wu H.
      • Yang S.
      • Guan W.
      The effect of socioeconomic and individual factors on acceptance levels of bariatric surgery among Chinese patients.
      ,
      • Topart P.
      Comment on: the effect of socioeconomic and individual factors on acceptance levels of bariatric surgery among Chinese patients.
      ).

       Update on Nonsurgical Therapies

      There are many bariatric surgical and nonsurgical procedures that are reimbursed by third-party payers, use U.S. Food and Drug Administration (FDA)-approved devices, or remain available through clinical investigative protocols (Fig. 2). Advancements in nonsurgical approaches to obesity include development of endoscopic bariatric therapies and approval of newer anti-obesity medications. Various endoscopic bariatric therapies function to reduce gastric volume by one of three techniques: (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ) reduce the stomach’s capacity via space-occupying devices, such as intragastric balloons, (
      NCD Risk Factor Collaboration
      Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19.2 million participants.
      ) remodel the stomach utilizing endoscopic suturing/plication devices, such as endoscopic sleeve gastroplasty, and (
      • Kontis V.
      • Mathers C.D.
      • Rehm J.
      • et al.
      Contribution of six risk factors to achieving the 25x25 non-communicable disease mortality reduction target: a modelling study.
      ) divert excess calories away from the stomach, such as aspiration therapy (
      • Sullivan S.
      • Edmundowicz S.A.
      • Thompson C.C.
      Endoscopic bariatric and metabolic therapies: new and emerging technologies.
      ). Three gastric balloons have been approved by the FDA since 2015 for patients with a BMI 30 to 40 kg/m2: the ReShape DuoTM (ReShape Medical, San Clemente, CA), the Orbera® intragastric balloon (Apollo EndoSurgery, Austin, TX), and the Obalon® Balloon (Obalon Therapeutics, Inc). Although these endoscopically placed devices are associated with short-term (6-month) weight loss, their utility and safety in long-term obesity management remain uncertain (

      U.S Food and Drug Administration. Liquid-filled intragastric balloon systems: letter to healthcare providers-potential risks. Available at https://www.fda.gov/medical-devices/letters-healthcare-providers/update-potential-risks-liquid-filled-intragastricballoons-letter-health-care-providers-0. Accessed March 15, 2018.

      ). The other nonsurgical resources for treatment of obesity are anti-obesity medications, which are well defined in guidelines for obesity treatment based on demonstrable weight-loss efficacy and associated metabolic improvements. Four medications have been approved by the FDA since 2012: phentermine/topiramate ER, lorcaserin, naltrexone/bupropion ER, and liraglutide 3.0 mg (
      • Igel L.I.
      • Kumar R.B.
      • Saunders K.H.
      • Aronne L.J.
      Practical Use of Pharmacotherapy for Obesity.
      ). Anti-obesity medications are approved by the FDA for patients with a BMI ≥30 kg/m2 without ORC, or ≥27 kg/m2 when associated with at least one ORC. Based primarily on retrospective data and personal experience, these medications are increasingly used in patients who have undergone bariatric surgery but have experienced either insufficient weight loss or frank weight regain.
      Fig. 2
      Fig. 2Current surgical and endoscopic bariatric procedures. The four surgical procedures shown are endorsed by the American Society of Metabolic and Bariatric Surgery. Laparoscopic sleeve gastrectomy comprises 70% of currently performed procedures, followed by laparoscopic gastric bypass (25%), adjustable gastric banding (3%), and duodenal switch (2%). Endoscopic procedures include aspiration therapy (AspireAssist*), space-occupying gastric devices (EllipseTM, Obalon®, Orbera®, ReshapeTM, SpatzTM balloons, and Gelesis capsule*), gastric-emptying device (Transpyloric Shuttle®**), and suturing/plication procedures (endoscopic sleeve gastroplasty with Apollo OverstitchTM and POSE procedure with the Incisionless Operating PlatformTM***). POSE = primary obesity surgery endoluminal.
      *FDA-approved devices; **FDA trial underway; ***Devices FDA approved for tissue approximation.
      Illustrations reprinted with permission from Atlas of Metabolic and Weight Loss Surgery, Jones et al. Cine-Med, 2010. Copyright of the book and illustrations are retained by Cine-Med.

       Update on Bariatric Surgery

      Significant additions to the evidence base have occurred since the publication of the 2013 TOS/ASMBS/AACE bariatric surgery CPG (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ). A PubMed computerized literature search (performed between January 1, 2013, and December 31, 2018) using the search term “bariatric surgery” revealed a total of 14,105 citations. Update of this 2019 CPG focuses on the most significant advances and changes in clinical care of the patient who undergoes bariatric surgery. Regarding procedure type, the sleeve gastrectomy (SG) has continued to trend upward, while the Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric band (LAGB) have trended downward. In one large database from 2015, the SG accounted for 63% of procedures performed, compared to 30% and 2% for RYGB and LAGB, respectively (
      • Kizy S.
      • Jahansouz C.
      • Downey M.C.
      • Hevelone N.
      • Ikramuddin S.
      • Leslie D.
      National trends in bariatric surgery 2012-2015: demographics, procedure selection, readmissions, and cost.
      ). The increase in SG is principally due to comparable metabolic and weightloss outcomes, but with lower complication rates (
      • Young M.T.
      • Gebhart A.
      • Phelan M.J.
      • Nguyen N.T.
      Use and outcomes of laparoscopic sleeve gastrectomy vs laparoscopic gastric bypass: analysis of the American College of Surgeons NSQIP.
      ) and fewer nutritional deficiencies, compared with RYGB.
      One of the most significant advances since the 2013 CPG has been the growing role of bariatric surgery in the treatment of patients with type 2 diabetes (T2D). A substantial body of evidence from 12 RCTs demonstrates that bariatric/metabolic surgery achieves superior improvements in glycemic-control metrics in patients with T2D, compared with various medical and lifestyle interventions. The improvement in glycemic control appears to be due to both weight loss–dependent and –independent effects (
      • Madsbad S.
      • Dirksen C.
      • Holst J.J.
      Mechanisms of changes in glucose metabolism and bodyweight after bariatric surgery.
      ). Based on these data, the Second Diabetes Surgery Summit Consensus Conference published guidelines in 2015 that were endorsed by more than 50 other organizations interested in the treatment of T2D (
      • Rubino F.
      • Nathan D.M.
      • Eckel R.H.
      • et al.
      Metabolic surgery in the treatment algorithm for type 2 diabetes: a joint statement by international diabetes organizations.
      ). According to these guidelines, metabolic surgery should be considered in patients with T2D and obesity (BMI >35.0 kg/m2) when hyperglycemia is inadequately controlled with lifestyle and optimal medical therapy. The 2016 Standards of Care for Diabetes from the American Diabetes Association (ADA) includes bariatric surgery in the treatment algorithm for T2D. Warren et al (
      • Warren J.A.
      • Ewing J.A.
      • Hale A.L.
      • Blackhurst D.W.
      • Bour E.S.
      • Scott J.D.
      Cost-effectiveness of bariatric surgery: increasing the economic viability of the most effective treatment for type II diabetes mellitus.
      ) demonstrated that in a population-based model where an increased number of bariatric surgeries are performed in patients with T2D, there is a substantial cost savings over a 10-year period, roughly $5.4 million per 1,000 patients.
      There have also been two cohort studies, six RCTs, and five meta-analyses published since 2013 that report mortality and cardiovascular outcomes, such as myocardial infarction, stroke, CVD risk and events, hypertension (HTN), and dyslipidemia (
      • Sjöström L.
      • Peltonen M.
      • Jacobson P.
      • et al.
      Association of bariatric surgery with long-term remission of type 2 diabetes and with microvascular and macrovascular complications.
      ,
      • Arterburn D.E.
      • Olsen M.K.
      • Smith V.A.
      • et al.
      Association between bariatric surgery and long-term survival.
      ,
      • Mingrone G.
      • Panunzi S.
      • De Gaetano A.
      • et al.
      Bariatric-metabolic surgery versus conventional medical treatment in obese patients with type 2 diabetes: 5 year follow-up of an open-label, singlecentre, randomised controlled trial.
      ,
      • Schauer P.R.
      • Bhatt D.L.
      • Kirwan J.P.
      • et al.
      Bariatric surgery versus intensive medical therapy for diabetes - 5-year outcomes.
      ,

      Cohen R, Le Roux CW, Junqueira S, Ribeiro RA, Luque A. Roux-en-Y gastric bypass in type 2 diabetes patients with mild obesity: a systematic review and meta-analysis. Obes Surg. 2017;27:2733-2739.

      ,
      • Müller-Stich B.P.
      • Senft J.D.
      • Warschkow R.
      • et al.
      Surgical versus medical treatment of type 2 diabetes mellitus in nonseverely obese patients: a systematic review and meta-analysis.
      ,
      • Gloy V.L.
      • Briel M.
      • Bhatt D.L.
      • et al.
      Bariatric surgery versus nonsurgical treatment for obesity: a systematic review and meta-analysis of randomised controlled trials.
      ,
      • Kwok C.S.
      • Pradhan A.
      • Khan M.A.
      • et al.
      Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.
      ,
      • Ricci C.
      • Gaeta M.
      • Rausa E.
      • Asti E.
      • Bandera F.
      • Bonavina L.
      Long-term effects of bariatric surgery on type II diabetes, hypertension and hyperlipidemia: a meta-analysis and meta-regression study with 5-year follow-up.
      ,
      • Halperin F.
      • Ding S.A.
      • Simonson D.C.
      • et al.
      Roux-en-Y gastric bypass surgery or lifestyle with intensive medical management in patients with type 2 diabetes: feasibility and 1-year results of a randomized clinical trial.
      ,
      • Ikramuddin S.
      • Billington C.J.
      • Lee W.J.
      • et al.
      Roux-en-Y gastric bypass for diabetes (the Diabetes Surgery Study): 2-year outcomes of a 5-year, randomised, controlled trial.
      ,
      • Courcoulas A.P.
      • Belle S.H.
      • Neiberg R.H.
      • et al.
      Three-year outcomes of bariatric surgery vs lifestyle intervention for type 2 diabetes mellitus treatment: a randomized clinical trial.
      ,
      • Cummings D.E.
      • Arterburn D.E.
      • Westbrook E.O.
      • et al.
      Gastric bypass surgery vs intensive lifestyle and medical intervention for type 2 diabetes: the CROSSROADS randomised controlled trial.
      ). Despite heterogeneity in study design, these data favor significantly improved CVD outcomes in patients undergoing bariatric surgery. DiaSurg 2, a randomized controlled multicenter trial comparing RYGB versus medical treatment in German patients with insulin-requiring T2D with BMI 26 to 35 kg/m2, is currently underway (
      • Kenngott H.G.
      • Clemens G.
      • Gondan M.
      • et al.
      DiaSurg 2 trial--surgical vs. medical treatment of insulin-dependent type 2 diabetes mellitus in patients with a body mass index between 26 and 35 kg/m2: study protocol of a randomized controlled multicenter trial--DRKS00004550.
      ). The primary endpoint is composite time-to-event using 8-year data, including CVD mortality, myocardial infarction, coronary bypass, percutaneous coronary intervention, nonfatal stroke, amputation, and surgery for peripheral atherosclerotic artery disease.
      The evolving role of bariatric procedures, or more generally speaking gastrointestinal (GI) procedures, to decrease cardiometabolic risk is more clearly envisioned within the nexus of ABCD and a newly proposed model of dysglycemia-based chronic disease (DBCD) (
      • Mechanick J.I.
      • Garber A.J.
      • Grunberger G.
      • Handelsman Y.
      • Garvey W.T.
      Dysglycemia-based chronic disease: an American Association of Clinical Endocrinologists position statement.
      ). In this model, abnormal adiposity intersects with stage-I DBCD as a driver for insulin resistance, T2D, and CVD (
      • Mechanick J.I.
      • Garber A.J.
      • Grunberger G.
      • Handelsman Y.
      • Garvey W.T.
      Dysglycemia-based chronic disease: an American Association of Clinical Endocrinologists position statement.
      ). The recent findings of a large, multicenter, retrospective matched cohort study by Fisher et al (
      • Fischer D.P.
      • Johnson E.
      • Haneuse S.
      • et al.
      Association between bariatric surgery and macrovascular disease outcomes in patients with type 2 diabetes and severe obesity.
      ) corroborate this concept. They found a lower risk of macrovascular outcomes associated with bariatric surgery in patients with T2D and severe obesity (
      • Fischer D.P.
      • Johnson E.
      • Haneuse S.
      • et al.
      Association between bariatric surgery and macrovascular disease outcomes in patients with type 2 diabetes and severe obesity.
      ). From a pragmatic standpoint, once this ABCD-DBCD model can be scientifically validated, decision-making for the use of GI interventional procedures on cardiometabolic risk reduction will be based on complication risk assessments, rather than just hemoglobin A1c (A1C), BMI, or other simplistic metrics.
      Quality of life was reported in two RCTs and improved in the patients undergoing bariatric surgery (
      • Mingrone G.
      • Panunzi S.
      • De Gaetano A.
      • et al.
      Bariatric-metabolic surgery versus conventional medical treatment in obese patients with type 2 diabetes: 5 year follow-up of an open-label, singlecentre, randomised controlled trial.
      ,
      • Schauer P.R.
      • Bhatt D.L.
      • Kirwan J.P.
      • et al.
      Bariatric surgery versus intensive medical therapy for diabetes - 5-year outcomes.
      ). The impact of bariatric surgery on skeleton and fracture risk has also been recently studied (
      • Lu C.W.
      • Chang Y.K.
      • Chang H.H.
      • et al.
      Fracture risk after bariatric surgery: a 12-year nationwide cohort study.
      ,
      • Yu E.W.
      • Lee M.P.
      • Landon J.E.
      • Lindeman K.G.
      • Kim S.C.
      Fracture risk after bariatric surgery: Roux-en-Y gastric bypass versus adjustable gastric banding.
      ,
      • Rousseau C.
      • Jean S.
      • Gamache P.
      • et al.
      Change in fracture risk and fracture pattern after bariatric surgery: nested case-control study.
      ). Follow-up data from the National Institutes of Health–supported, prospective cohort Longitudinal Assessment of Bariatric Surgery continue to inform clinical care regarding various aspects of postoperative management, including weight-loss trajectories (
      • Courcoulas A.P.
      • Christian N.J.
      • Belle S.H.
      • et al.
      Weight change and health outcomes at 3 years after bariatric surgery among individuals with severe obesity.
      ), behavioral variables, 3-year weight changes (
      • Mitchell J.E.
      • Christian N.J.
      • Flum D.R.
      • et al.
      Postoperative behavioral variables and weight change 3 years after bariatric surgery.
      ), and risks for developing alcohol-use disorder (
      • King W.C.
      • Chen J.Y.
      • Courcoulas A.P.
      • et al.
      Alcohol and other substance use after bariatric surgery: prospective evidence from a U.S. multicenter cohort study.
      ). Lastly, postoperative weight regain is recognized as a significant clinical issue that requires focused attention.

       The American Board of Obesity Medicine

      Based on the increased prevalence and burden of overweight and obesity among U.S. adults and children, a distinct need for more advanced competency in the field of obesity, burgeoning approaches in obesity care expected to continue over the next decade, and complex perioperative care of the patient undergoing bariatric surgery, the American Board of Obesity Medicine (ABOM) was established in 2011 (www.abom.org). Certification as an ABOM diplomate signifies specialized knowledge in the practice of obesity medicine and distinguishes a physician as having achieved competency in obesity care. As of 2018, over 2,600 physicians have become Diplomates, of which over half co-manage patients who have undergone bariatric surgery (
      • Kushner R.
      • Brittan D.
      • Cleek J.
      • et al.
      The American Board of Obesity Medicine: fivey-ear report.
      ). This team-based approach to bariatric surgery that also includes dietitians, mental health professionals, and advanced practitioners (e.g., nurse practitioner and physician assistant) is important in perioperative management. Thus, the tactical approach to an obesity epidemic that can effectively implement evidence-based strategies, as well as increase exposure of health-care professionals (HCP) to patients having bariatric surgery, mandates leadership roles of experts and champions for obesity care, development of formal obesity-care teams, and a friendly logistical infrastructure to facilitate favorable outcomes.

      METHODS

      The Boards of Directors for the AACE, TOS, ASMBS, OMA, and American Society of Anesthesiologists (ASA) approved this update of the 2008 (
      • Mechanick J.I.
      • Kushner R.F.
      • Sugerman H.J.
      • et al.
      American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery medical guidelines for clinical practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient.
      ) and 2013 (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ) AACE/TOS/ASMBS Medical Guidelines for Clinical Practice for the Perioperative Nutritional, Metabolic, and Nonsurgical Management of the Bariatric Surgery Patient. Selection of the co-chairs, primary writers, and reviewers, as well as the logistics for creating this 2019 evidence-based CPG update were conducted in strict adherence with the AACE Protocol for Standardized Production of Clinical Practice Guidelines, Algorithms, and Checklists – 2017 Update (2017 Guidelines for Guidelines; 2017 G4GAC) (
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      ) (Table 2, Table 3, Table 4, Table 5). This updated CPG methodology provides for patient-first language (“patient undergoing bariatric procedures” instead of disease-first language: “bariatric patient”) and greater detail for evidence ratings and structure for the involvement of the American College of Endocrinology Scientific Referencing Subcommittee, a dedicated resource for the rating of evidence, mapping of grades, and general oversight of the entire CPG production process. In addition, the term “bariatric procedure” is used to broadly apply to both surgical and nonsurgical procedures. However, when the evidence specifically pertains to surgical procedures, then the term “bariatric surgery” is used. A critical improvement in the 2017 G4GAC is to create documents that are easier to use and less cumbersome. Nevertheless, as with all white papers and increasing diligence on the part of the writing team and sponsoring professional medical organizations, there remains an element of subjectivity that must be recognized by the reader when interpreting the information. (See Table 6a, Table 6b, Table 6c.)
      Table 2Step I AACE G4GAC: Evidence Rating
      Based on principle that interventions, scientific control, generalizability, methodological flaws, and evidentiary details determine strength, consistent with other evidence-based methodology systems. Numerical and semantic descriptors of evidence levels provided in online supplementary material.
      Numerical descriptor
      The original numerical description from G4GAC 2004, 2010, and 2014 are provided in parentheses.
      Semantic descriptorMethodology descriptor
      STRONG EVIDENCE
      1 (1)RCTRandomized controlled trial
      The superiority of RCT over all other studies, and in particular MRCT, is discussed in reference elsewhere.
      1 (1)MRCTMeta-analysis of only randomized controlled trials
      INTERMEDIATE EVIDENCE
      2 (2)MNRCTMeta-analysis including nonrandomized prospective or case-controlled trials
      2 (new)NMANetwork meta-analysis
      2 (2)NRCTNonrandomized controlled trial (or unconfirmed randomization)
      2 (2)PCSProspective cohort study (does not include open-label extension study)
      2 (2)RCCSRetrospective case-control study
      2 (new)NCCSNested case-control study
      2 (3; re-assigned)CSSCross-sectional study
      2 (3; re-assigned)ESEpidemiologic study (hypothesis driven; includes survey, registry, datamining, with or without retrospective uni-multivariate analyses or propensity matching)
      2 (new)OLESOpen-label extension study
      2 (new)PHASPost hoc analysis study
      WEAK EVIDENCE
      3 (new)DSDiscovery science (explorative/inductive; includes -omics, “big data,” network analysis, systems biology, Bayesian inference, modeling)
      3 (new)ECONEconomic study (includes Markov models, pharmaco-economics)
      3 (3)CCSConsecutive case series (N > 1)
      3 (3)SCRSingle case report (N = 1)
      3 (new)PRECLINPreclinical study (e.g., feasibility, safety)
      3 (new)BRBasic research (must be high impact and relevant)
      NO EVIDENCE
      4 (4)NENo evidence (theory, opinion, consensus, review, position, policy, guideline)
      4 (new)OOther (e.g., lower impact/relevant basic research; any highly flawed study)
      Abbreviations: AACE = American Association of Clinical Endocrinologists; G4GAC = Guidelines for Guidelines, Algorithms, and Checklists.
      Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      a Based on principle that interventions, scientific control, generalizability, methodological flaws, and evidentiary details determine strength, consistent with other evidence-based methodology systems. Numerical and semantic descriptors of evidence levels provided in online supplementary material.
      b The original numerical description from G4GAC 2004, 2010, and 2014 are provided in parentheses.
      c The superiority of RCT over all other studies, and in particular MRCT, is discussed in reference elsewhere.
      Table 3Step II AACE G4GAC – Scientific Analysis and Subjective Factors
      These subjective factors pertain to an individual citation. Subjective factors are provided in online supplementary material from (55).
      Study design
      These subjective factors pertain to an individual citation. Subjective factors are provided in online supplementary material from (55).
      Data analysis
      Are these elements appropriate for the given study?
      Interpretation of results
      Allocation concealment (randomization)Intent-to-treatGeneralizability
      Blinding
      Including patients, clinicians, data collectors, adjudicators of outcome, and data analysts.
      Modeling (e.g., Markov)Incompleteness
      Comparator groupNetwork analysisLogical
      Endpoints (real clinical vs. surrogate)StatisticsOverstated
      HypothesisAppropriate follow-upValidity
      Power analysis (too small sample size)Appropriate trial termination
      Premise
      Type 1 error (e.g., adjusted for PHAS)
      Abbreviations: AACE = American Association of Clinical Endocrinologists; G4GAC = Guidelines for Guidelines, Algorithms, and Checklists; PHAS = post hoc analysis study.
      a These subjective factors pertain to an individual citation. Subjective factors are provided in online supplementary material from
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      b Are these elements appropriate for the given study?
      c Including patients, clinicians, data collectors, adjudicators of outcome, and data analysts.
      Table 4Step III AACE G4GAC – Recommendation Qualifiers
      Each of these elements pertains to the recommendation statement with the evidence considered in aggregate. The element may be positive or negative and therefore modify a final recommendation grade. Recommendation qualifiers are provided in online supplementary material from (55). Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021 (55).
      Cascades (are there other recommendation versions based on ethnocultural factors?
      Dissenting opinions (based on HCP and patient preferences)
      Economic (e.g., cost-effectiveness, cost-benefit, value)
      Evidence base (are there significant gaps or is there overwhelming evidence?)
      Relevance (patient-oriented evidence that matters vs. disease-oriented evidence; social acceptability)
      Resource availability (limited or sufficient)
      Risk to benefit
      Abbreviations: AACE = American Association of Clinical Endocrinologists; G4GAC = Guidelines for Guidelines, Algorithms, and Checklists; HCP = health-care professional(s).
      * Each of these elements pertains to the recommendation statement with the evidence considered in aggregate. The element may be positive or negative and therefore modify a final recommendation grade. Recommendation qualifiers are provided in online supplementary material from
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      Table 5Step IV AACE G4GAC – Creating Initial Recommendation Grades
      Recommendation Grade A = “Very Strong”; B = “Strong”; C = “Not Strong”; D = “Primarily Based on Expert Opinion.” Mappings are provided in online supplementary material from (55).
      Best evidence levelPredominantly negative SF and/or RQPredominantly positive SF and/or RQConsensus for recommendation and for gradeEL to grade mappingMap to final recommendation grade
      1NoNo>66%Direct1 → A
      Any
      Rule-based adjustment wherein any recommendation can be a “Very Strong” Grade A if there is 100% consensus to use this designation. Similarly, if >66% consensus is not reached, even with some degree of scientific substantiation, a “Primarily Based on Expert Opinion” Grade D designation is assigned. The reasons for downgrading to D may be an inconclusive or inconsistent evidence base or simply failure of the expert writing committee to sufficiently agree. Note that any formulated recommendation is omitted from the document if sufficiently flawed, so any Grade D recommendation in the final document must be deemed sufficiently important. Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021 (55).
      NoNo100%RuleAny → A (new)
      2NoYes>66%Adjust up2 → A
      2NoNo>66%Direct2 → B
      1YesNo>66%Adjust down1 → B
      3NoYes>66%Adjust up3 → B
      3NoNo>66%Direct3 → C
      2YesNo>66%Adjust down2 → C
      4NoYes>66%Adjust up4 → C
      4NoNo>66%Direct4 → D
      3YesNo>66%Adjust down3 → D
      Any
      Rule-based adjustment wherein any recommendation can be a “Very Strong” Grade A if there is 100% consensus to use this designation. Similarly, if >66% consensus is not reached, even with some degree of scientific substantiation, a “Primarily Based on Expert Opinion” Grade D designation is assigned. The reasons for downgrading to D may be an inconclusive or inconsistent evidence base or simply failure of the expert writing committee to sufficiently agree. Note that any formulated recommendation is omitted from the document if sufficiently flawed, so any Grade D recommendation in the final document must be deemed sufficiently important. Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021 (55).
      Yes/noYes/no>66%RuleAny → AD (new)
      Abbreviations: AACE = American Association of Clinical Endocrinologists; BEL = best evidence level; EL = evidence level; G4GAC = Guidelines for Guidelines, Algorithms, and Checklists; RQ = recommendation qualifiers; SF = subjective factors.
      a Recommendation Grade A = “Very Strong”; B = “Strong”; C = “Not Strong”; D = “Primarily Based on Expert Opinion.” Mappings are provided in online supplementary material from
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      b Rule-based adjustment wherein any recommendation can be a “Very Strong” Grade A if there is 100% consensus to use this designation. Similarly, if >66% consensus is not reached, even with some degree of scientific substantiation, a “Primarily Based on Expert Opinion” Grade D designation is assigned. The reasons for downgrading to D may be an inconclusive or inconsistent evidence base or simply failure of the expert writing committee to sufficiently agree. Note that any formulated recommendation is omitted from the document if sufficiently flawed, so any Grade D recommendation in the final document must be deemed sufficiently important.Reprinted with permission from Mechanick et al. Endocr Pract. 2017;23:1006-1021
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      .
      Table 6aGuiding Bariatric Procedure Selection Based on Risks, Benefits, and Target Weight Loss: Procedures Endorsed by ASMBS and Possibly Covered by Insurance
      Selection of the specific bariatric procedure is done after a decision is made to have a bariatric procedure. Estimate of bariatric surgery numbers can be found at http://asmbs.org/resources/estimate-of-bariatric-surgery-numbers. (Accessed March 25, 2018).
      Procedure (ref)Target weight loss (%TBWL)Favorable aspectsUnfavorable aspects
      LAGB
      • O’Brien P.E.
      • Hindle A.
      • Brennan L.
      • et al.
      Long-term outcomes after bariatric surgery: a systematic review and meta-analysis of weight loss at 10 or more years for all bariatric procedures and a single-centre review of 20-year outcomes after adjustable gastric banding.
      20%-25%-No anatomic alteration

      -Removable

      -Adjustable
      -High explant rate

      -Erosion

      -Slip/Prolapse
      SG
      • O’Brien P.E.
      • Hindle A.
      • Brennan L.
      • et al.
      Long-term outcomes after bariatric surgery: a systematic review and meta-analysis of weight loss at 10 or more years for all bariatric procedures and a single-centre review of 20-year outcomes after adjustable gastric banding.
      25%-30%-Easy to perform

      -No anastomosis

      -Reproducible

      -Few long-term complications

      -Metabolic effects

      -Versatile for challenging patient populations
      -Leaks difficult to manage

      -Little data beyond 5 years

      -20%-30% GERD
      RYGB
      • O’Brien P.E.
      • Hindle A.
      • Brennan L.
      • et al.
      Long-term outcomes after bariatric surgery: a systematic review and meta-analysis of weight loss at 10 or more years for all bariatric procedures and a single-centre review of 20-year outcomes after adjustable gastric banding.
      30%-35%-Strong metabolic effects

      -Standardized techniques

      -<5% major complication rate

      -Effective for GERD

      -Can be used as second stage after SG
      -Few proven revisional options for

      weight regain

      -Marginal ulcers

      -Internal hernias possible

      -Long-term micronutrient deficiencies
      BPD/DS
      • O’Brien P.E.
      • Hindle A.
      • Brennan L.
      • et al.
      Long-term outcomes after bariatric surgery: a systematic review and meta-analysis of weight loss at 10 or more years for all bariatric procedures and a single-centre review of 20-year outcomes after adjustable gastric banding.
      35%-45%-Very strong metabolic effects

      -Durable weight loss

      -Effective for patients with very high BMI

      -Can be used as second stage after SG
      -Malabsorptive

      -3%-5% protein-calorie malnutrition

      -GERD

      -Potential for internal hernias

      -Duodenal dissection

      -Technically challenging

      -Higher rate of micronutrient

      deficiencies than RYGB
      Abbreviations: ASMBS = American Society of Metabolic and Bariatric Surgery; BMI = body mass index; GERD = gastroesophageal reflux disease; GI = gastrointestinal; HTN = hypertension; IGB = intragastric balloon; LAGB = laparoscopic adjustable gastric banding; LBPD/DS = laparoscopic biliopancreatic diversion with duodenal switch; LRYGB = laparoscopic Roux-en-Y gastric bypass; LSG = laparoscopic sleeve gastrectomy; MetS = metabolic syndrome; NAFLD = nonalcoholic fatty liver disease; NASH = nonalcoholic steatohepatitis; ORC = obesity-related complication; OSA = obstructive sleep apnea; PCOS = polycystic ovary syndrome; TBWL = total body weight loss; T2D = type 2 diabetes; vBLOC = vagal nerve-blocking device.
      * Selection of the specific bariatric procedure is done after a decision is made to have a bariatric procedure. Estimate of bariatric surgery numbers can be found at http://asmbs.org/resources/estimate-of-bariatric-surgery-numbers. (Accessed March 25, 2018).
      Table 6bGuiding Bariatric Procedure Selection Based on Risks, Benefits, and Target Weight Loss: Procedures and Devices Not Currently Covered by Insurance
      Procedure (ref)Target weight loss (%TBWL)Favorable aspectsUnfavorable aspects
      Primary obesity surgery endoluminal (POSE)
      • López-Nava G.
      • Bautista-Castaño Jimenez A.
      • de Grado T.
      • Fernandez-Corbelle J.P.
      The Primary Obesity Surgery Endolumenal (POSE) procedure: one-year patient weight loss and safety outcomes.
      5%-Endoscopic

      -4.7% adverse events

      -Device FDA approved for tissue apposition
      -Pain (45%)

      -Nausea (21%)

      -Vomiting (19%)

      -? Durability
      Gelesis100 (ingested Hydrogel capsules)6%-Swallowed, noninvasive

      -Not absorbed

      -No major adverse events

      -Increased fullness

      -FDA approved
      -Minor gastrointestinal side effects

      -Only 24-week trial, no long-term data
      vBLOC
      • Shhikora S.A.
      • Wolfe B.M.
      • Apovian C.M.
      • et al.
      Sustained weight loss with vagal nerve blockade but not with sham: 18-month results of the ReCharge Trial.
      ,
      • Apovian C.M.
      • Shah S.N.
      • Wolfe B.M.
      • et al.
      Two-year outcomes of vagal nerve blocking (vBloc) for the treatment of obesity in the ReCharge Trial.
      8-9%-No anatomic changes

      -Low complication rate (4%)

      -FDA approved
      -Pain at neuroregulatory site

      -Explant required for conversion to another procedure
      Intragastric balloon
      • Sullivan S.
      • Edmundowicz S.A.
      • Thompson C.C.
      Endoscopic bariatric and metabolic therapies: new and emerging technologies.
      ,
      • Ponce J.
      • Woodman G.
      • Swain J.
      • et al.
      The REDUCE pivotal trial: a prospective, randomized controlled pivotal trial of a dual intragastric balloon for the treatment of obesity.
      ,
      • Bariatric A.S.G.E.
      Endoscopy Task Force and ASGE Technology Committee, Abu Dayyeh BK, Kumar N, et al. ASGE Bariatric Endoscopy Task Force systematic review and meta-analysis assessing the ASGE PIVI thresholds for adopting endoscopic bariatric therapies.
      10-12%-Endoscopic or swallowed

      -Good safety profile

      -FDA approved
      -Temporary (6-month) therapy

      -Temporary n/v, pain

      -Early removal rate 10%-19%
      AspireAssist
      • Thompson C.C.
      • Abu Dayyeh B.K.
      • Kushner R.
      • et al.
      Percutaneous gastrostomy device for the treatment of class II and class III obesity: results of a randomized controlled trial.
      12-14%-Endoscopic

      -Changes eating behavior

      -FDA approved
      -1-year therapy

      -Tube-related problems/complications

      -26% early removal
      Transpyloric shuttle
      • Haskins O.
      TransPyloric Shuttle demonstrates weight loss.
      14%-Endoscopic

      -Delays gastric emptying

      -FDA approved
      -6-month data

      -Gastric ulcers
      Endoscopic sleeve gastroplasty (ESG)
      • Lopez-Nava G.
      • Sharaiha R.Z.
      • Vargas E.J.
      • et al.
      Endoscopic sleeve gastroplasty for obesity: a multicenter study of 248 patients with 24 months follow-up.
      16-20%-Endoscopic

      -Low adverse event rate

      -Device FDA approved for tissue apposition
      -One study, 2-year data

      -No RCTs

      -? Durability
      Abbreviations: FDA = U.S. Food and Drug Administration; TBWL = total body weight loss; vBLOC = vagal nerve-blocking device, n/v = nausea/vomiting, RCT = randomized controlled trial.
      Table 6cGuiding Bariatric Procedure Selection Based on Risks, Benefits, and Target Weight Loss: Emerging Procedures Not Currently Covered by Insurance or Endorsed by ASMBS
      Institutional review board (IRB) or IRB exemption required (https://asmbs.org/resources/endorsed-procedures-and-devices).
      Procedure (ref)Target weight loss (%TBWL)Favorable aspectsUnfavorable aspects
      Laparoscopic greater curvature plication (LGP)
      • Abdelbaki T.N.
      • Huang C.K.
      • Ramos A.
      • Neto M.G.
      • Talebpour M.
      • Saber A.A.
      Gastric plication for morbid obesity: a systematic review.
      15-25%-Non-resectional

      -No staplers or devices

      -Reversible/revisable
      -Limited data beyond 2 years

      -GERD

      -Difficult to standardize

      -Disruption of plication

      -Dilation of stomach

      -Not “leak-proof”
      OAGB
      • O’Brien P.E.
      • Hindle A.
      • Brennan L.
      • et al.
      Long-term outcomes after bariatric surgery: a systematic review and meta-analysis of weight loss at 10 or more years for all bariatric procedures and a single-centre review of 20-year outcomes after adjustable gastric banding.
      35-40%-Simpler to perform than RYGB

      -More malabsorptive

      -Strong metabolic effects

      -No mesenteric defects
      -Potential for bile reflux

      -Malabsorptive (long BP limb)

      -Little experience in U.S.
      OADS (SIPS, SADI-S)
      • Neichoy B.T.
      • Schniederjan B.
      • Cottam D.R.
      • et al.
      Stomach intestinal pylorus-sparing surgery for morbid obesity.
      ,
      • Abdelbaki T.N.
      • Huang C.K.
      • Ramos A.
      • Neto M.G.
      • Talebpour M.
      • Saber A.A.
      Gastric plication for morbid obesity: a systematic review.
      35-45%-Single anastomosis

      -Simpler to perform than BPD/DS

      -Strong metabolic effects

      -Low early complication rate
      -Little long-term data

      -Nutritional and micronutrient deficiencies possible

      -Duodenal dissection
      Abbreviations: ASMBS = American Society of Metabolic and Bariatric Surgery; BPD/DS = biliopancreatic diversion with duodenal switch; GERD = gastroesophageal reflux disease; OAGB = one-anastomosis gastric bypass; OADS = one-anastomosis duodenal switch; RYGB = Roux-en-Y gastric bypass; SIPS = stomach intestinal pylorus-sparing; SADI-S = single anastomosis duodeno-ileal bypass with sleeve gastrectomy; TBWL = total body weight loss.
      a Institutional review board (IRB) or IRB exemption required (https://asmbs.org/resources/endorsed-procedures-and-devices).
      Key Updates are provided to highlight the most important new recommendations in this CPG. The Executive Summary is reorganized into seven clinical questions and provides updated recommendation numbers (R1, R2, R3, … R85) in their entirety followed by the respective publication year of the creation or last update in parentheses and an indication of updated explanations and/or references by an asterisk. In many cases, recommendations have been condensed for clarity and brevity. In other cases, recommendations have been expanded for more clarity to assist with complex and/or nuanced-based decision-making. The relevant evidence base, supporting tables, and figures for the updated recommendations follow the Executive Summary in an Appendix. The reader is encouraged to refer to the 2008 (
      • Mechanick J.I.
      • Kushner R.F.
      • Sugerman H.J.
      • et al.
      American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery medical guidelines for clinical practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient.
      ) and 2013 (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ) AACE-TOS-ASMBS CPG for background material not covered in this 2019 update.

       Key Updates for 2019

      • Technical: there is an increased amount and quality of recent evidence to guide clinical decision-making; the analysis of evidence is based on the updated 2017 G4GAC; there are now five sponsoring professional medical societies that provide a greater fund of expert knowledge and higher level of diligence in the iterative review process.
      • Disease Context: the role for surgical and nonsurgical bariatric procedures has been re-examined in a complications-centric framework of ABCD and DBCD, providing the potential for greater precision for clinical decision-making based on biological correlates, clinical relevance, cardiometabolic risk assessment, and ethnicity-related differences in anthropometrics.
      • Procedure Selection: new and emergent surgical and nonsurgical bariatric procedures are introduced and described, nuanced criteria for bariatric procedures are better defined, and an algorithm with supporting tables and checklists are provided to assist the reader with decision-making.
      • Perioperative Protocols: proactive interventions to improve postoperative outcomes with an emphasis on perioperative enhanced recovery after bariatric surgery (ERABS) clinical pathways are presented and elaborated.

      EXECUTIVE SUMMARY

      There are 85 numbered recommendations in this 2019 update, compared with 74 updated recommendations in 2013 and 164 original recommendations in 2008. There are 12 new recommendations in this 2019 update (14%), and among the others, 61 were revised (72%). Unanimous consensus among primary writers was obtained for each of the recommendations. Updated recommendation numbers are indicated by the most recent update year, updated evidence by an asterisk after the year, and new recommendations by “NEW.” The semantic descriptors of “must,” “should,” and “may” generally, but not strictly, correlate (or map) with Grade A (strong), Grade B (intermediate), and Grade C (weak) recommendations, respectively; each semantic descriptor can be used with Grade D (no conclusive evidence and/or expert opinion) recommendations. Deviations from this mapping are not unusual and take into consideration further decision-making requirements, logistics, and subjective factors. Bariatric procedures include both surgical and nonsurgical procedures; the latter are generally performed endoscopically. Recommendations are oriented to the procedure type based on the respective evidence base and expert opinion.
      Q1. Which patients should be offered bariatric procedures?
      R1. (2019*). Patients with a body mass index ≥40 kg/m2 without co-existing medical problems and for whom bariatric procedures would not be associated with excessive risk are eligible for a bariatric procedure (Grade A; BEL 1).
      R2. (2019*). Patients with a body mass index (BMI) ≥35 kg/m2 and one or more severe obesity-related complications remediable by weight loss, including type 2 diabetes (T2D), high risk for T2D (insulin resistance, prediabetes, and/or metabolic syndrome), poorly controlled hypertension, nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, obstructive sleep apnea, osteoarthritis of the knee or hip, and urinary stress incontinence, should be considered for a bariatric procedure (Grade C; BEL 3). Patients with the following comorbidities and BMI ≥35 kg/m2 may also be considered for a bariatric procedure, though the strength of evidence is more variable: obesity-hypoventilation syndrome and Pickwickian syndrome after a careful evaluation of operative risk; idiopathic intracranial hypertension; gastroesophageal reflux disease; severe venous stasis disease; impaired mobility due to obesity; and considerably impaired quality of life (Grade C; BEL 3).
      R3. (2019*). Patients with body mass index 30 to 34.9 kg/m2 and type 2 diabetes with inadequate glycemic control despite optimal lifestyle and medical therapy should be considered for a bariatric procedure; current evidence is insufficient to support recommending a bariatric procedure in the absence of obesity (Grade B; BEL 2).
      R4. (NEW). The body mass index criterion for bariatric procedures should be adjusted for ethnicity (e.g., 18.5 to 22.9 kg/m2 is normal range, 23 to 24.9 kg/m2 overweight, and ≥25 kg/m2 obesity for Asians) (Grade D).
      R5. (2019*). Bariatric procedures should be considered to achieve optimal outcomes regarding health and quality of life when the amount of weight loss needed to prevent or treat clinically significant ORC cannot be obtained using only structured lifestyle change with medical therapy (Grade B; BEL 2).
      Q2. Which bariatric procedure should be offered?
      R6. (2019*). Selecting a bariatric procedure should be based on individualized goals of therapy (e.g., weight-loss target and/or improvements in specific obesity-related complications), available local-regional expertise (obesity specialists, bariatric surgeon, and institution), patient preferences, personalized risk stratification that prioritizes safety, and other nuances as they become apparent (Table 6) (Grade C; BEL 3). Notwithstanding technical surgical reasons, laparoscopic bariatric procedures should be preferred over open bariatric procedures due to lower early postoperative morbidity and mortality (Grade B; BEL 2). Laparoscopic adjustable gastric banding, laparoscopic sleeve gastrectomy, laparoscopic Roux-en-Y gastric bypass, and laparoscopic biliopancreatic diversion without/with duodenal switch (LBPD/DS), or related procedures should be considered as primary bariatric and metabolic procedures performed in patients requiring weight loss and/or amelioration of obesity-related complications (Grade A; BEL 1). Physicians must exercise caution when recommending biliopancreatic diversion (BPD), BPD with duodenal switch (BPD/DS), or related procedures because of the greater associated nutritional risks related to the increased length of bypassed small intestine (Grade A; BEL 1). Newer nonsurgical bariatric procedures may be considered for selected patients who are expected to benefit from short-term (i.e., about 6 months) intervention with ongoing and durable structured lifestyle with/without medical therapy (Grade C; BEL 3). Investigational procedures may be considered for selected patients based on available institutional review board–approved protocols, suitability for clinical targets, and individual patient factors, and only after a careful assessment balancing the importance for innovation, patient safety, and demonstrated effectiveness (Grade D).
      Rule-based adjustments are provided in online supplementary material from (
      • Mechanick J.I.
      • Pessah-Pollack R.
      • Camacho P.
      • et al.
      American Association of Clinical Endocrinologists and American College of Endocrinology protocol for standardized prodcution of clinical practice guidelines, algorithms, and checklists -- 2017 Update.
      ).
      Q3. How should potential candidates be managed before bariatric procedures?
      R7. (2008). Patients must undergo pre-procedure evaluation for obesity-related complications and causes of obesity, with special attention directed to those factors that could influence a recommendation for bariatric procedures (see Pre-operative Checklist in Table 7) (Grade A; BEL 1) and consider a referral to a specialist in obesity medicine (Grade D).
      R8. (2008). The pre-procedure evaluation must include a comprehensive medical history, psychosocial history, physical examination, and appropriate laboratory testing to assess surgical risk (see Pre-operative Checklist in Table 7) (Grade A; BEL 1).
      R9. (2008). Medical records should contain clear documentation of the indications for bariatric surgery (Grade D).
      R10. (2019*). Because informed consent is a dynamic process, there must be a thorough discussion with the patient regarding the risks and benefits, procedural options, choices of surgeon and medical institution, and the need for long-term follow-up and vitamin supplementation (including costs required to maintain appropriate follow-up and nutrient supplementation) (Grade D). Patients must also be provided with educational materials, which are culturally and educationally appropriate, as well as access to similar pre-operative educational sessions at prospective bariatric surgery centers (Grade D). Consent should include experience of the surgeon with the specific procedure offered and whether the hospital has an accredited bariatric surgery program (Grade D).
      R11. (2013). The bariatric surgery program must be able to provide all necessary financial information and clinical material for documentation so that, if needed, third-party payer criteria for reimbursement are met (Grade D).
      R12. (2013). Pre-procedure weight loss can reduce liver volume and may help improve the technical aspects of surgery in patients with an enlarged liver or fatty liver disease and therefore may be recommended before a bariatric procedure (Grade B; BEL 1; downgraded due to inconsistent evidence). Pre-procedure weight loss or medical nutritional therapy may be recommended to patients in selected cases to improve comorbidities, such as pre-procedure glycemic targets (Grade D).
      • STEP 1: Identify durable target weight loss beyond that achieved with lifestyle and medications to mitigate relevant ORCs -- a primary determinant of an optimal procedure selection:
      • o
        >5%-10% weight loss: T2D, dyslipidemia, HTN, NAFLD, low testosterone, OSA/reactive airway disease, urinary stress incontinence, PCOS
      • o
        >10%-15% weight loss: MetS, prediabetes, NASH, osteoarthritis, GERD, depression (
        • Garvey W.T.
        • Mechanick J.I.
        • Brett E.M.
        • et al.
        American Association of Clinical Endocrinologists and American College of Endocrinology comprehensive clinical practice guidelines for medical care of patients with obesity.
        ).
      • STEP 2: Identify other factors that can affect decision-making, including: durability, eating behaviors, surgeon skills, institutional experience, cardiometabolic effects, prior GI surgery, and GI disease. “Favorable” aspects show key parameters to favor selection of the respective procedure. “Unfavorable” aspects show key parameters against selection of the respective procedure.
      Q4. What are the elements of medical clearance for bariatric procedures?
      R13. (NEW). A lifestyle medicine checklist should be completed as part of a formal medical clearance process for all patients considered for any bariatric procedure (Table 7) (Grade D).
      Table 7Preprocedure Checklist (including Lifestyle Medicine)
      Based on information included in Mechanick et al. Endocr Pract. 2013;19:337-372 (1).
      Complete H & P (obesity-related comorbidities, causes of obesity, weight, BMI, weight-loss history, commitment, and exclusions related to surgical risk)
      Routine labs (including fasting blood glucose and lipid panel, kidney function, liver profile, lipid profile, urine analysis, prothrombin time/INR, blood type, CBC
      Nutrient screening with iron studies, B12 and folic acid (RBC folate, homocysteine, methylmalonic acid optional), and 25-vitamin D (vitamins A and E optional); consider more extensive testing in patients undergoing malabsorptive procedures based on symptoms and risks
      Cardiopulmonary evaluation with sleep apnea screening (ECG, CSR, echocardiography if cardiac disease or pulmonary hypertension suspected; deep-venous thrombosis evaluation, if clinically indicated
      GI evaluation (H. pylori screening in areas of high prevalence; gallbladder evaluation and upper endoscopy, if clinically indicated)
      Endocrine evaluation (A1C with suspected or diagnosed prediabetes or diabetes; TSH with symptoms or increased risk of thyroid disease; androgens with PCOS suspicion (total/bioavailable testosterone, DHEAS, Δ4-androstenedione); screening for Cushing syndrome if clinically suspected (1 mg overnight dexamethasone test, 24-hour urinary free cortisol, 11 pm salivary cortisol)
      Lifestyle medicine evaluation: healthy eating index; cardiovascular fitness; strength training; sleep hygiene (duration and quality); mood and happiness; alcohol use; substance abuse; community engagement
      Clinical nutrition evaluation by RD
      Psychosocial-behavioral evaluation
      Assess for individual psychological support/counseling
      Document medical necessity for bariatric surgery
      Informed consent
      Provide relevant financial information
      Continue efforts for pre-operative weight loss
      Optimize glycemic control
      Pregnancy counseling
      Smoking-cessation counseling
      Verify cancer screening by primary care physician
      Abbreviations: BMI = body mass index; CBC = complete blood count; CSR = Cheyne Stokes respiration; ECG = electrocardiogram; GI = gastrointestinal; INR = international normalized ratio; PCOS = polycystic ovary syndrome; RBC = red blood cell; RD = registered dietician; DHEAS = dehydroepiandrosterone-sulfate; TSH = thyroid-stimulating hormone.
      a Based on information included in Mechanick et al. Endocr Pract. 2013;19:337-372 (1).
      R14. (2019*). Pre-procedure glycemic control must be optimized using a diabetes comprehensive care plan, including healthy low-calorie dietary patterns, medical nutrition therapy, physical activity, and, as needed, pharmacotherapy (Grade A; BEL 1). Reasonable targets for pre-operative glycemic control, which may be associated with shorter hospital stays and improved bariatric procedure outcomes, include an A1C value of 6.5% to 7.0% (48 to 53 mmol/mol) or less and peri-procedure blood glucose levels of 80 to 180 mg/dL (Grade B; BEL 2). More liberal pre-procedure targets, such as an A1C of 7% to 8% (53 to 64 mmol/mol), are recommended in patients with advanced microvascular or macrovascular complications, extensive comorbid conditions, or long-standing diabetes in which the general goal has been difficult to attain despite intensive efforts (Grade A; BEL 1). In patients with A1C >8% or otherwise uncontrolled diabetes, clinical judgment determines the need and timing for a bariatric procedure (Grade D).
      R15. (2013*). Routine screening for primary hypothyroidism with a thyroid-stimulating hormone (TSH) level before a bariatric procedure is not recommended, though many insurance plans require a pre-procedure serum TSH level (Grade D). A serum TSH level should be obtained only if clinical evidence of hypothyroid is present (Grade B; BEL 2). Patients found to be hypothyroid must be treated with levothyroxine monotherapy (Grade A; BEL 1).
      R16. (2019*). A fasting lipid panel should be obtained in all patients with obesity (Grade A; BEL 1). Treatment should be initiated according to available and current clinical practice guidelines (see www.aace.com/files/lipid-guidelines.pdf and www.lipid.org/recommendations) (Grade D).
      R17. (2013*). Candidates for bariatric procedures should avoid pregnancy pre-procedure and for 12 to 18 months post-procedure (Grade D). Women who become pregnant after bariatric procedures should be counseled and monitored for appropriate weight gain, nutritional supplementation, and fetal health (Grade C; BEL 3). All women of reproductive age should be counseled on contraceptive choices before and after bariatric procedures (Grade D). Patients undergoing RYGB or another malabsorptive procedure should be counseled about non-oral contraceptive therapies (Grade D). Patients who become pregnant following bariatric procedure should have nutritional surveillance and laboratory screening for nutrient deficiencies every trimester, including iron, folate, vitamin B12, vitamin D, and calcium, and if after a malabsorptive procedure, fat-soluble vitamins, zinc, and copper (Grade D). Patients who become pregnant post-laparoscopic adjustable gastric band should have band adjustments as necessary for appropriate weight gain for fetal health (Grade B; BEL 2).
      R18. (2008*). Estrogen therapy should be discontinued before a bariatric procedure (1 cycle of oral contraceptives in premenopausal women; 3 weeks of hormone replacement therapy in postmenopausal women) to reduce the risks for post-procedure thromboembolic phenomena (Grade D).
      R19. (2008*). Women should be advised that their fertility status might be improved after a bariatric procedure (Grade D).
      R20. (2019*). Case-by-case decisions to screen for monogenic and syndromic causes of obesity should be based on specific historical and physical findings. (Grade D).
      R21. (2019*). The need for an electrocardiogram and other noninvasive cardiac testing is determined on the basis of the individual risk factors and findings on history and physical examination and should be based on the latest American College of Cardiology/American Heart Association guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery (http://circ.ahajournals.org/content/early/2014/07/31/CIR.0000000000000106) (Grade D). Patients with known heart disease require a formal cardiology consultation before bariatric procedures (Grade D). Patients at risk for heart disease must undergo evaluation for peri-procedure b-adrenergic blockade (Grade A; BEL 1).
      R22. (2019*). In patients evaluated for bariatric procedures, clinical screening for obstructive sleep apnea (with confirmatory polysomnography if screening tests are positive) should be considered (Grade C, BEL 3). Patients with intrinsic lung disease or disordered sleep patterns should have a formal pulmonary evaluation, including arterial blood gas measurement, when knowledge of the results would alter patient care (Grade C; BEL 3).
      R23. (2019*). Tobacco use must be avoided at all times by all patients. In particular, patients who smoke cigarettes should stop as soon as possible, preferably 1 year, but at the very least, 6 weeks before bariatric procedures (Grade A; BEL 2, upgraded by consensus). Also, tobacco use must be avoided after bariatric procedures given the increased risk of poor wound healing, anastomotic ulcer, and overall impaired health (Grade A; BEL 1). Structured intensive cessation programs are preferable to general advice and should be implemented (Grade D).
      R24. (2013*). Patients with a history of deep venous thrombosis (DVT) or cor pulmonale should undergo a risk assessment for bariatric surgery and an appropriate diagnostic evaluation for DVT (Grade D). In selecting treatment approaches to prevent thrombosis, the routine placement of a vena cava filter is discouraged; however, prophylactic placement of a vena cava filter may be considered in individual patients after careful evaluation of the risks and benefits (Grade C; BEL 3).
      R25. (2019*). Clinically significant gastrointestinal (GI) symptoms should be evaluated before bariatric procedures with imaging studies, upper GI series, or endoscopy (Grade D). The use of pre-operative endoscopy may be considered in all patients being evaluated for sleeve gastrectomy (Grade D).
      R26. (2019*). Imaging studies are not recommended as a routine screen for liver disease (Grade B, BEL 2). Abdominal ultrasound is indicated to evaluate symptomatic biliary disease and elevated liver function tests (Grade C, BEL 3). Abdominal ultrasonography or elastography may be helpful and may be considered to identify nonalcoholic fatty liver disease, but may not be diagnostic (Grade B, BEL 2). Consideration can be made for liver biopsy at the time of a bariatric procedure to document steatohepatitis and/or cirrhosis that may otherwise be unknown due to normal appearance on imaging and/or liver function tests (Grade C, BEL 3). A comprehensive evaluation is recommended in those patients with clinically significant and persistent abnormal liver function tests (Grade A; upgraded by consensus rule).
      R27. (2013*). Routine screening for the presence of Helicobacter pylori before bariatric procedures may be considered in areas of high prevalence (Grade C; BEL 3).
      R28. (2013*). Prophylactic treatment for gouty attacks should be considered before bariatric procedures in patients with a history of gout (Grade C, BEL 3).
      R29. (2008*). There are insufficient data to warrant pre-procedure assessment of bone mineral density with dual-energy X-ray absorptiometry (DXA) or serum or urinary bone turnover markers outside formal recommendations by the National Osteoporosis Foundation (http://www.iscd. org/documents/2014/10/nof-clin-guidelines.pdf/) (Grade D).
      R30. (2019*). A formal psychosocial-behavioral evaluation performed by a qualified behavioral health professional (i.e., licensed in a recognized behavioral health discipline, such as psychology, social work, psychiatry, psychiatric nursing, etc., with specialized knowledge and training relevant to obesity, eating disorders, and/or bariatric procedures), which assesses environmental, familial, and behavioral factors, as well as risk for suicide, should be required for all patients before a bariatric procedure (Grade C; BEL 3). Any patient considered for a bariatric procedure with a known or suspected psychiatric illness, or substance abuse or dependence, should undergo a formal mental health evaluation before the procedure (Grade C; BEL 3). Following Roux-en-Y gastric bypass and sleeve gastrectomy, high-risk groups should eliminate alcohol consumption due to impaired alcohol metabolism and risk of alcohol-use disorder postoperatively (Grade C; BEL 3).
      R31. (2013*). All patients should undergo evaluation of their ability to incorporate nutritional and behavioral changes before and after any bariatric procedure (Grade C; BEL 3).
      R32. (2013*). All patients must undergo an appropriate nutritional evaluation, including micronutrient measurements, before any bariatric procedure (Table 7) (Grade A; BEL 1). In comparison with purely restrictive procedures, more extensive nutritional evaluations are required for malabsorptive procedures (Grade A; BEL 1). Whole-blood thiamine levels may be considered in patients prior to bypass procedures (Roux-en-Y gastric bypass and biliopancreatic diversion with duodenal switch) (Grade C; BEL 3).
      R33. (2013*). Patients should be followed by their primary-care physician and have age- and risk-appropriate cancer screening before bariatric procedures (Grade C; BEL 3).
      R34. (NEW). Pre-operative enhanced recovery after bariatric surgery (ERABS) clinical pathways should be implemented in all patients who are having bariatric surgery to improve postoperative outcomes (Grade D). Comprehensive pre-operative optimization (prehabilitation) should be implemented, including but not limited to deep breathing exercises, continuous positive airway pressure (CPAP) as appropriate, incentive spirometry, leg exercises, continued oral nutrition with carbohydrates, including sips of clear liquids up to 2 hours pre-operatively, H2 blocker or proton-pump inhibitor, opioid-sparing multimodal analgesia, thromboprophylaxis, and education about perioperative protocols (Table 8) (Grade B; BEL 2).
      Table 8Summary of AHRQ Safety Program for Improving Surgical Care and Enhanced Recovery after Bariatric Surgery (ERABS)
      Based on information included in Grant et al. Anesth Analg. 2018 (855); Thorell et al. World J Surg. 2016;40:2065-2083 (568); Ljungqvist et al. JAMA. 2017;152:292-298 (856); Alvarez et al. Curr Opin Anaesthesiol. 2017;30:133-139 (593); and Bellamy et al. Perioper Med (Lond). 2013;2:12 (549).
      Protocol Component/InterventionOutcome
      Immediate Pre-operative
      Carbohydrate loadingDecrease insulin resistance

      Decrease protein catabolism, LOS

      Faster return of bowel function
      Reduced fastingNo adverse outcomes
      Multimodal pre-anesthesia medicationDecreased pain, PONV, opioid use
      Intra-operative
      Standard intra-operative anesthesia pathwayDecreased pain, PONV, opioid use
      Protective ventilation strategiesDecreased pulmonary complications
      Goal-directed fluid managementDecrease morbidity, LOS
      Postoperative nausea and vomiting prophylaxisDecreased PONV
      Regional blockDecreased pain, opioid use
      Postoperative
      Standard multimodal analgesia regimenDecreased pain, PONV, opioid use
      Early ambulationDecreased VTE
      Early return of oral intakeEasier return of bowel function
      Abbreviations: AHRQ = Agency for Healthcare Research and Quality; LOS = length of stay; PONV = postoperative nausea and vomiting; VTE = venous thromboembolism.
      a Based on information included in Grant et al. Anesth Analg. 2018
      • Grant M.C.
      • Gibbons M.M.
      • Ko C.Y.
      • et al.
      Evidence review conducted for the agency for healthcare resarch and quality safety program for improving surgical care and recovery: focus on anesthesiology for bariatric surgery.
      ; Thorell et al. World J Surg. 2016;40:2065-2083
      • Thorell A.
      • MacCormick A.D.
      • Awad S.
      • et al.
      Guidelines for perioperative care in bariatric surgery: enhanced recovery after surgery (ERAS) society recommendations.
      ; Ljungqvist et al. JAMA. 2017;152:292-298
      • Ljungqvist O.
      • Scott M.
      • Fearon K.C.
      Enhanced recovery after surgery: a review.
      ; Alvarez et al. Curr Opin Anaesthesiol. 2017;30:133-139
      • Alvarez A.
      • Goudra B.G.
      • Singh P.M.
      Enhanced recovery after bariatric surgery.
      ; and Bellamy et al. Perioper Med (Lond). 2013;2:12
      • Bellamy M.C.
      • Margarson M.P.
      Designing intelligent anesthesia for a changing patient demographic: a consensus statement to provide guidance for specialist and non-specialist anesthetists written by members of and endorsed by the Society for Obesity and Bariatric Anaesthesia (SOBA).
      .
      Q5. How can care be optimized during and within 5 days of a bariatric procedure?
      R35. (NEW). Appropriate perioperative enhanced recovery after bariatric surgery (ERABS) clinical pathways should be implemented in all patients undergoing bariatric surgery (Table 8) (Grade D). Routine pulmonary recruitment maneuvers should be performed intra-operatively as needed (Grade D). Intra-operative use of dexmedetomidine may be considered to decrease perioperative opioid use (Grade C; BEL 3). Intra-operative protocols to detect possible silent bleeding sites should be performed (Grade D). Consider dynamic indicators to guide goal-directed fluid therapy to avoid excess intra-operative fluid administration (Grade B; BEL 2).
      R36. (NEW). A postoperative checklist should be reviewed and implemented (Table 9). Appropriate postoperative enhanced recovery after bariatric surgery (ERABS) clinical pathways should be implemented in all patients who have had bariatric surgery (Table 8) (Grade D).
      Table 9Postprocedure Checklist
      Based on information included in Mechanick et al. Endocr Pract. 2013;19:337-372 and Parrott et al. Surg Obes Rel Dis. 2017;13:727-741 (1, 448).
      Checklist ItemLAGBSGRYGBBPD/DS
      Early postoperative care
      monitored telemetry at least 24 h if high risk for MI
      protocol-derived staged meal progression supervised by RD
      healthy eating education by RD
      multivitamin plus minerals (# tablets for minimal requirement)1222
      elemental calcium (as calcium citrate)1,200-1,500 mg/d1,200-1,500 mg/d1,200-1,500 mg/d1,800-2,400 mg/d
      vitamin D, at least 3,000 units/d, titrate to >30 ng/mL
      vitamin B12 as needed for normal range levels
      maintain adequate hydration (usually >1.5 L/d PO)
      monitor blood glucose with diabetes or hypoglycemic symptoms
      pulmonary toilet, spirometry, DVT prophylaxis
      if unstable, consider PE, ILPEPEPE/ILPE/IL
      if rhabdomyolysis suspected, check CPK
      Follow-up
      visits: initial, interval until stable, once stable (months)1, 1-2, 121, 3, 6, 121, 3, 6-121, 3, 6
      monitor progress with weight loss and evidence of complications each visit
      SMA-21, CBC/plt with each visit (and iron at baseline and after as needed)
      avoid nonsteroidal anti-inflammatory drugs
      adjust postoperative medications
      consider gout and gallstone prophylaxis in appropriate patients
      need for antihypertensive therapy with each visit
      lipid evaluation every 6-12 months based on risk and therapy
      monitor adherence with physical activity recommendations
      evaluate need for support groups
      bone density (DXA) at 2 years
      24-h urinary calcium excretion at 6 months and then annually
      This testing should be considered for any patient after a bariatric procedure at 6 months and then annually if there is a history of renal stones.
      xxx
      B12 (annually; MMA and HCy optional; then q 3-6 months if supplemented)
      folic acid (RBC folic acid optional), iron studies, 25-vitamin D, iPTHxx
      vitamin A (initially and q 6-12 months thereafter)xxoptional
      copper, zinc, selenium evaluation with specific findingsxx
      thiamine evaluation with specific findings
      consider eventual body contouring surgery
      lifestyle medicine evaluation: healthy eating index; cardiovascular fitness; strength training; sleep hygiene (duration and quality); mood and happiness; alcohol use; substance abuse; community engagement
      hemoglobin A1c, TSH evaluation in long-term follow-up
      Abbreviations: BPD/DS = biliopancreatic diversion with duodenal switch; CBC = complete blood count; CPK = creatine phosphokinase; DVT = deep vein thrombosis; DXA = dual-energy X-ray absorptiometry; HCy = homocysteine; IL = intestinal leak; iPTH = intact parathyroid hormone; LAGB = laparoscopic adjustable gastric band; MI = myocardial infarction; MMA = methylmalonic acid; PE = pulmonary embolus; plt = platelets; PO = orally; q = daily; RBC = red blood cell; RD = registered dietician; RYGB = Roux-en-Y gastric bypass; SG = sleeve gastrectomy; SMA-21 = chemistry panel; TSH = thyroid-stimulating hormone.
      a Based on information included in Mechanick et al. Endocr Pract. 2013;19:337-372 and Parrott et al. Surg Obes Rel Dis. 2017;13:727-741
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ,
      • Parrott J.
      • Frank L.
      • Rabena R.
      • Craggs-Dino L.
      • Isom K.A.
      • Greiman L.
      American Society for Metabolic and Bariatric Surgery integrated health nutritional guidelines for the surgical weight loss patient 2016 update: micronutrients.
      .
      b This testing should be considered for any patient after a bariatric procedure at 6 months and then annually if there is a history of renal stones.
      R37. (NEW). Pre-emptive anti-emetic and non-opioid analgesic medications immediately before and during bariatric procedures as part of a multimodal pain management strategy should be implemented to decrease early post-procedure opioid use and postoperative nausea and vomiting (Grade C; BEL 3).
      R38. (2013*). A low-sugar clear liquid meal program can usually be initiated within 24 hours after any of the surgical bariatric procedures, but this diet and meal progression should be discussed with the surgeon and guided by the registered dietician (RD) (Table 10) (Grade C; BEL 3). A consultation for postoperative meal initiation and progression must be arranged with an RD who is knowledgeable about the postoperative bariatric diet (Grade A, BEL 1). Patients should receive education in a protocol-derived staged meal progression based on their surgical procedure (Grade D). Patients should be counseled to eat 3 small meals during the day and chew small bites of food thoroughly before swallowing (Grade D). Patients should be counseled about the principles of healthy eating, including at least 5 daily servings of fresh fruits and vegetables (Grade D). Protein intake should be individualized, assessed, and guided by an RD, regarding gender, age, and weight (Grade D). A minimal protein intake of 60 g/d and up to 1.5 g/kg ideal body weight per day should be adequate; higher amounts of protein intake—up to 2.1 g/kg ideal body weight per day—need to be assessed on an individualized basis (Grade D). Concentrated sweets should be eliminated from the diet after Roux-en-Y gastric bypass to minimize symptoms of the dumping syndrome, as well as after any bariatric procedure to reduce caloric intake (Grade D). Crushed or liquid rapid-release medications should be used instead of extended-release medications to maximize absorption in the immediate post-procedure period (Grade D).
      Table 10Dietary Recommendations Following Bariatric Procedure
      RecommendationsUpToDate: Postoperative Nutritional Management
      • Kushner R.
      • Cummings S.
      • Herron D.M.
      Bariatric surgery: postoperative nutritional management.
      2008 ASMBS Allied Health Nutritional Guidelines
      • Aills L.
      • Blankenship L.
      • Buffington C.
      • Furtado M.
      • Parrott J.
      ABMBS allied health nutritional guidelines for the surgical weight loss patient.
      Guidelines for Perioperative Care in Bariatric Surgery: ERAS Society Recommendations
      • Thorell A.
      • MacCormick A.D.
      • Awad S.
      • et al.
      Guidelines for perioperative care in bariatric surgery: enhanced recovery after surgery (ERAS) society recommendations.
      Academy of Nutrition and Dietetics Pocket Guide to Bariatric Surgery, 2nd ed
      Diet ProgressionSurgeon or institution specific

      Stage 1 and 2: Hydration and liquids

      • Clear liquid diet (brief period)
      • Full liquids and possibly pureed foods -- which includes liquid sources of protein and small amounts of carbohydrates (up to several weeks after surgery)
      Stage 3: Solid foods with an emphasis on protein sources, some carbohydrates, and fiber (~10-14 days after surgery)

      Stage 4: Micronutrient supplementation (when patient reaches a stable or maintenance weight)

      Long-term diet:

      • Roux-en-Y gastric bypass -- well balanced diet containing all the essential nutrients; possible postoperative diets may include
      • o
        My Plate
      • o
        DASH Diet
      The Vegetarian Resource Group

      • Sleeve gastrectomy – same advancement and recommendations post-SG as for post-RYGB
      • LAGB – generally resume a normal diet soon after surgery
      • • Biliopancreatic diversion/duodenal switch -- small, nutrient-dense meals that are high in protein, along with fruits, vegetables, whole grains, and omega-3 fatty acids, and avoidance of concentrated sweets
      Diet Stage:

      Clear liquid (1 to 2 days after surgery)

      • Sugar-free or low sugar
      Full liquid (10-14 days after surgery)

      • Sugar-free or low
      sugar

      Pureed (10-14+ days)

      • Foods that have been blended or liquefied with adequate fluid
      Mechanically altered soft (>14 days after surgery)

      • Textured-modified
      • Require minimal chewing
      • Chopped, ground, mashed, flaked or pureed foods
      Regular textured (6-8 weeks after surgery)

      * Purpose of nutrition care after surgical weight loss procedures:

      • Adequate energy and nutrients to support tissue healing after surgery and support preservation of lean body mass during extreme weight loss
      • Foods and beverages must minimize reflux, early satiety, and dumping syndrome while maximizing weight loss and weight maintenance
      Clear liquid meal regimen initiated a couple of hours postoperatively

      Balanced meal plan to include:

      • >5 servings of fruit and vegetables daily for optimal fiber consumption, colonic function, and phytochemical intake
      Avoid concentrated sweets to reduce caloric intake and to minimize symptoms of dumping (gastric bypass)
      Postoperative nutrition care of the bariatric patient has 2 distinct stages during the first year:

      • 0-3 months
      • 3 months-1 year
      Typically described in stages:

      • Diet Stage 1: Clear Liquid Diet – very short-term; used in the hospital on postoperative days (POD) 1 and 2; liquids low in calories and sugar and free of caffeine, carbonation, and alcohol
      • Diet Stage 2: Full Liquid Diet – started between POD 2 and POD 3; continues for ~14 days; clear liquids + full liquids that are low in sugar with up to 25-30 g protein per serving
      • Diet Stage 3: Soft Food Texture Progression – timing varies by type of surgery and duration depends on patient’s response to foods; replace protein-containing full liquids with soft, semi-solid protein sources (moist, soft, diced, ground or pureed), 3-5 times/day, as tolerated
      • Diet Stage 4: Regular Solid Food Diet
      FluidsThroughout all the diet stages, patients should be counseled to consume adequate fluid to prevent dehydrationN/A>1.5 L daily48-64 ounces (oz)/d

      • Women: 48 oz/d
      • Men: 64 oz/d
      • 50% goal should be met with clear liquids
      Protein46 g/day – women

      56 g/day – men

      Protein needs:

      • Should constitute 10-35% of daily caloric intake
      • Weight maintenance: 0.8-1.2 g/kg body weight per day
      • Active weight loss: 1.2 g/kg body weight (BPD/DS may require 1.5-2.0 g/kg body weight per day)
      Exact needs have yet to be definedShould average 60-20 g dailyGuidelines for protein consumption not defined
      Carbohydrates
      • Early postop – 50 g/day
      • As diet intake increases – 130 g/day
      N/AN/AN/A
      Fat20-35% of the daily caloric intake; bulk of the fat intake should be unsaturated fatN/AN/AN/A
      Behavior
      • Eat slowly
      • Chew food extensively
      • Stop eating as soon as reach satiety
      • Avoid taking food and beverages at the same time
      • • Simple sugars should be limited to less than 10% of daily caloric intake
      Avoid/Delay

      • Concentrated sweets
      • Carbonated beverages
      • Fruit juice
      • High-saturated fat, fried foods
      • Soft doughy bread, pasta, rice
      • Tough, dry, red meat
      • Nuts, popcorn, other fibrous foods
      • Caffeine
      • Alcohol
      • Multiple small meals each day
      • Chewing food thoroughly without drinking beverages at the same time
      • Consume fluids slowly
      • Practice mindful eating
      • Chew all food until it is smooth
      • Make sure food is soft and moist enough to swallow without sticking
      • Do not drink liquids during meals
      • Wait 30 minutes after eating before resuming fluid intake
      • Avoid bread, rice and pasta until able to comfortably consume adequate protein, vegetables and fruits
      OtherClose monitoring with a registered dietitianDietitian’s role is a vital component of the bariatric surgery process

      Follow up with registered dietitian
      Nutritional and meal planning guidance should be provided to patient and family before bariatric surgery and during the postoperative hospital course and reinforced at subsequent outpatient visits

      Consultation should be provided with a dietitian and a protocol-derived staged meal progression, based on the type of surgical procedure, should be adhered to
      • RD responsible for the nutrition care of the post-surgery patient and plays an important role in every aspect of care, from pre-operative assessment of the patient to long-term follow-up, evaluation, and monitoring
      Abbreviations: ASMBS = American Society of Metabolic and Bariatric Surgery; BPD/DS = biliopancreatic diversion with duodenal switch; DASH = detary approaches to stop hypertension; ERAS = enhanced recovery after surgery; LAGB = laparoscopic adjustable gastric band; N/A = not applicable; RD = registered dietician; RYGB = Roux-en-Y gastric bypass; SG = sleeve gastrectomy.
      R39. (2019*). After consideration of pre-procedure deficiency states, as well as risks and benefits in the early (<5 days) post-procedure period, patients with, or at risk for, demonstrable micronutrient insufficiencies or deficiencies must be treated with the respective micronutrient, and then adjusted based on recommendations for the late post-procedure period (Table 9, Table 11, Table 12) (Grade A, BEL 2, upgraded by consensus). Minimal daily nutritional supplementation for patients with biliopancreatic diversion with/without duodenal switch, Roux-en-Y gastric bypass, and sleeve gastrectomy should be in chewable form initially, and as 2 adult multivitamins plus minerals (each containing iron, folic acid, and thiamine) (Grade B, BEL 2), elemental calcium (1,200 to 1,500 mg/d for sleeve gastrectomy and Roux-en-Y gastric bypass and 1,800 to 2,400 mg/d for biliopancreatic diversion with duodenal switch in diet and as citrated supplement in divided doses) (Grade B, BEL 2), at least 2,000 to 3,000 international units of vitamin D (titrated to therapeutic 25-hydroxyvitamin D levels >30 ng/mL) (Grade A, BEL 1), total iron as 18 to 60 mg via multivitamins and additional supplements (Grade A, BEL 1), and vitamin B12 (parenterally as sublingual, subcutaneous, or intramuscular preparations, or orally, if determined to be adequately absorbed) (Grade B; BEL 2). Minimal daily nutritional supplementation for patients with laparoscopic adjustable gastric banding should include 1 adult multivitamin plus minerals (including iron, folic acid, and thiamine) (Grade B, BEL 2), 1,200 to 1,500 mg/d of elemental calcium (in diet and as citrated supplement in divided doses), and at least 2,000 to 3,000 international units of vitamin D (titrated to therapeutic 25-dihydroxyvitamin D levels) (Grade B, BEL 2). Additional recommendations to prevent micronutrient deficiencies are included in Table 9, Table 11, Table 12.
      Table 11Nutrient Deficiencies After Bariatric Procedures
      Vitamin/MineralPrevalence of DeficiencyScreening
      Vitamin B1 (Thiamine)<1-49% depending on procedure and post WLS time frameRecommended for high-risk groups

      • Patients with risk factors for thiamin deficiency
      • Females
      • African Americans
      • Patients not attending a nutritional clinic after surgery
      • Patients with GI symptoms (intractable nausea and vomiting, jejunal dilation, mega-colon, or constipation)
      • Patients with concomitant conditions such as cardiac failure (especially those receiving furosemide)
      • Patients with SBBO
      • Other risk factors such as malnutrition, excessive and/or rapid weight loss, and excessive alcohol use increase the risk of thiamin deficiency
      Post-WLS patients with signs and symptoms or risk factors should be assessed for thiamin deficiency at least during the first 6 months and then every 3-6 months until symptoms resolve
      Vitamin B12 (Cobalamin)at 2-5 years post-WLS

      • RYGB: <20%
      • • SG: 4-20%
      Recommended for patients who have undergone RYGB, SG, or BPD/DS

      More frequent screening (every 3 months) recommended in the first-year post-surgery, and then at least annually or as clinically indicated for patients who chronically use medications that exacerbate risk of B12 deficiency, such as nitrous oxide, neomycin, metformin, colchicine, proton-pump inhibitors, and seizure medications

      Screening should include serum MMA with or without homocysteine to identify metabolic deficiency of B12 in symptomatic and asymptomatic patients and in patients with history of B12 deficiency or preexisting neuropathy

      Vitamin B12 deficiencies can occur due to food intolerances or restricted intake of protein and vitamin B12-containing foods
      Folate (Folic Acid)Up to 65% of patientsScreening recommended for all patients

      Particular attention should be given to female patients of childbearing age

      Poor dietary intake of folate-rich foods and suspected nonadherence with multivitamin may contribute to folate deficiency
      Iron3 months-10 years post-WLS

      • AGB: 14%
      • SG: <18%
      • RYGB: 20-55%
      • BPD: 13-62%
      • • DS: 8-50%
      Iron deficiency can occur after any bariatric procedure, despite routing supplementation

      Routine postbariatric screening is recommended within 3 months after surgery, and then every 3 to 6 months until 12 months, and annually thereafter for all patients

      Iron status should be monitored in postbariatric patients at regular intervals using an iron panel, complete blood count, total iron-binding capacity, ferritin, and soluble transferrin receptor (if available), along with clinical signs and symptoms

      Additional screening should be performed based on clinical signs and symptoms and/or laboratory findings or in cases where deficiency is suspected
      Vitamin D and CalciumUp to 100% of patientsRoutine screening is recommended for all patients

      25(OH)D is the preferred biochemical assay

      Elevated PTH levels and increased bone formation/resorption markers may also be considered
      Vitamin AUp to 70% of patients within 4 years post-surgeryScreening is recommended within the first postoperative year, particularly for those who underwent BPD/DS, regardless of symptoms

      Screening is recommended in patients who have undergone RYGB and BPD/DS, particularly in those with evidence of protein-calorie malnutrition
      Vitamin EUncommonScreening is recommended in patients who are symptomatic
      Vitamin KUncommonScreening is recommended in patients who are symptomatic
      ZincUp to 70% of patients post-BPD/DS

      Up to 40% of patients post-RYGB

      Up to 19% of patients post-SG

      Up to 34% of patients post-AGB
      Zinc deficiency is possible, even during zinc supplementation and especially if primary sites of absorption (duodenum and proximal jejunum) are bypassed

      Screening should be performed at least annually post-RYGB and post-BPD/DS

      Serum and plasma zinc are the preferred biomarkers for screening in post-bariatric patients
      CopperUp to 90% in patients post-BPD/DS

      10-20% in patients post-RYGB

      1 case report for patients post-SG

      No data for patients post-AGB
      Screening is recommended at least annually after BPD/DS and RYGB, even in the absence of clinical signs or symptoms

      Serum copper and ceruloplasmin are recommended biomarkers for determining copper status because they are closely correlated with physical symptoms of copper deficiency
      Abbreviations: 25(OH)D = 25-hydroxyvitamin D; AGB = adjustable gastric band; BPS/DS = biliopancreatic diversion/duodenal switch; GI = gastrointestinal; MMA = methylmalonic acid; PTH = parathyroid hormone; RYGB = Roux-en-Y gastric bypass; SBBO = small bowel bacterial overgrowth; SG = sleeve gastrectomy; WLS = weight loss surgery.
      Table 12Nutrient Supplementation and Repletion After Bariatric Surgery
      MicronutrientSupplementation to Prevent DeficiencyRepletion for Patients with Deficiency
      Vitamin B1 (Thiamine)12 mg thiamine daily; preferably a 50-100 mg daily dose of thiamine from a B-complex supplement or high-potency multivitaminBariatric patients with suspected thiamine deficiency should be treated before or in the absence of laboratory confirmation and monitored/evaluated for resolution of signs and symptoms

      Repletion dose for thiamine deficiency varies based on route of administration and severity of symptoms:

      • Oral therapy: 100 mg 2-3 times daily until symptoms resolve
      • IV therapy: 200 mg 3 times daily to 500 mg once or twice daily for 3-5 d, followed by 250 mg/d for 3-5 d or until symptoms resolve, then consider treatment with 100 mg/d orally, indefinitely, or until risk factors have been resolved
      • IM therapy: 250 mg once daily for 3-5 d or 100-250 mg monthly
      Magnesium, potassium, and phosphorus should be given simultaneously to patients at risk for refeeding syndrome
      Vitamin B12 (Cobalamin)Supplement dose varies based on route of administration

      • Orally by disintegrating tablet, sublingual, or liquid: 350-1,000 μg daily
      • Nasal spray as directed by manufacturer
      • • Parenteral (IM or SQ): 1,000 μg monthly
      1,000 μg/d to achieve normal levels and then resume dosages recommended to maintain normal levels
      Folate (Folic Acid)400-800 μg oral folate daily from their multivitamin

      800-1,000 μg oral folate daily in women of child-bearing age
      Oral dose of 1000 μg of folate daily to achieve normal levels and then resume recommended dosage to maintain normal levels

      >1 mg/d supplementation is not recommended because of the potential masking of vitamin B12 deficiency
      IronMales and patients without a history of anemia: 18 mg of iron from multivitamin

      Menstruating females and patients who have undergone RYGB, SG, or BPD/DS: 45-60 mg of elemental iron daily (cumulatively, including iron from all vitamin and mineral supplements)

      Oral supplementation should be taken in divided doses

      separately from calcium supplements, acid-reducing medications, and foods high in phytates or polyphenols
      Oral supplementation should be increased to provide 150-200 mg of elemental iron daily to amounts as high as 300 mg 2-3 times daily

      Oral supplementation should be taken in divided doses separately from calcium supplements, acid-reducing medications, and foods high in phytates or polyphenols

      Vitamin C supplementation may be added to increase iron absorption and decrease risk of iron overload

      IV iron infusion should be administered if iron deficiency does not respond to oral therapy
      Vitamin D and CalciumAppropriate dose of daily calcium from all sources varies by surgical procedure

      • BPD/DS: 1,800-2,400 mg/d
      • LAGB, SG, RYGB: 1,200-1,500 mg/d
      To enhance calcium absorption in post-WLS patients

      • Calcium should be given in divided doses
      • Calcium carbonate should be taken with meals
      • Calcium citrate may be taken with or without meals
      Recommended preventative dose of vitamin D should be based on serum vitamin D levels

      • Recommended vitamin D3 dose is 3,000 IU daily, until blood levels of 25(OH)D are greater than sufficient (30 ng/mL)
      • • 7-90% lower vitamin D3 bolus is needed (compared to vitamin D2) to achieve the same effects as those produced in healthy nonbariatric surgical patients
      All bariatric patients with vitamin D deficiency or insufficiency should be repleted as follows:

      • Vitamin D3 at least 3,000 IU/d and as high as 6,000 IU/d, or 50,000 IU vitamin D2 1-3 times weekly

      • Vitamin D3 is recommended over vitamin D2 as a more potent treatment when comparing frequency and amount needed for repletion

      Repletion of calcium deficiency varies by surgical procedure:

      • BPD/DS: 1,800-2,400 mg/d
      • • LAGB, SG, RYGB: 1,200-1,500 mg/d
      Vitamin ADosage is based on type of procedure:

      • LAGB: 5,000 IU/d
      • RYGB and SG: 5,000-10,000 IU/d
      • DS: 10,000 IU/d
      Higher maintenance doses of fat-soluble vitamins may be required for bariatric patients with a previous history of vitamin A deficiency

      Water-miscible forms of fat-soluble vitamins are also available to improve absorption

      Special attention should be paid to post-bariatric supplementation of vitamin A in pregnant women
      For bariatric patients with vitamin A deficiency without corneal changes, a dose of 10,000-25,000 IU/d of vitamin A should be given orally until clinical improvement is evident

      For bariatric patients with vitamin A deficiency with corneal changes, a dose of 50,000-100,000 IU of vitamin A should be administered IM for 3 d, followed by 50,000 IU/d IM for 2 weeks

      Bariatric patients with vitamin A deficiency should also be evaluated for concurrent iron and/or copper deficiencies because these can impair resolution of vitamin A deficiency
      Vitamin E15 mg/d

      Higher maintenance doses of fat-soluble vitamins may be required for postbariatric patients with a previous history of vitamin E deficiency

      Water-miscible forms of fat-soluble vitamins are also available to improve absorption
      Optimal therapeutic dose of vitamin E for bariatric patients is not defined

      Potential antioxidant benefits can be achieved with supplements of 100-400 IU/d, which is higher than the amount found in multivitamins.

      Additional supplementation may be required for repletion
      Vitamin KDosage is based on type of procedure:

      • LAGB: 90-120 μg/d
      • RYGB and SG: 90-120 μg/d
      • DS: 300 μg/d
      Higher maintenance doses of fat-soluble vitamins may be required for post-WLS patients with a previous history of vitamin K deficiency

      Water-miscible forms of fat-soluble vitamins are also available to improve absorption

      Special attention should be paid to post-WLS supplementation of vitamin K in pregnant women
      A parenteral dose of 10 mg is recommended for bariatric patients with acute malabsorption

      A dose of either 1-2 mg/d orally or 1-2 mg/week parenterally is recommended for post-WLS patients with chronic malabsorption
      ZincAll post-WLS patients should take 4 RDA zinc, with dosage based on type of procedure

      • BPD/DS: Multivitamin with minerals containing 200% of the RDA (16-22 mg/d)
      • RYGB: Multivitamin with minerals containing 100-200% of the RDA (8-22 mg/d)
      • SG/LAGB: Multivitamin with minerals containing 100% of the RDA (8-11 mg/d)
      The supplementation protocol should contain a ratio of 8-15 mg of supplemental zinc per 1 mg of copper to minimize the risk of copper deficiency

      The formulation and composition of zinc supplements should be considered in post-WLS patients to calculated accurate levels of elemental zinc provided by the supplement
      A dose-related recommendation for repletion cannot be made due to insufficient evidence

      Repletion doses should be chosen carefully to avoid inducing a copper deficiency

      Zinc status should be routinely monitored using consistent parameters throughout treatment
      CopperAll post-WLS patients should take 4 RDA copper as part of routine multivitamin and mineral supplementation, with dosage based on type of procedure:

      • BPD/DS or RYGB: 200% of the RDA (2 mg/d)
      • SG or LAGB: 100% of the RDA (1 mg/d)
      Supplementation with 1 mg copper is recommended for every 8-15 mg of elemental zinc to prevent copper deficiency in all post-WLS patients

      Copper gluconate or sulfate is the recommended source of copper for supplementation
      Recommended repletion regimen varies with severity of deficiency:

      • Mild to moderate (including low hematologic indices): 3-8 mg/d oral copper gluconate or sulfate until indices return to normal
      • Severe: 2-4 mg/d intravenous copper can be initiated for 6 d or until serum levels return to normal and neurologic symptoms resolve
      • • Copper levels should be monitored every 3 months after they return to normal
      Abbreviations: 25(OH)D = 25-hydroxyvitamin D; BPD/DS = biliopancreatic diversion/duodenal switch; IM = intramuscular; IV = intravenous; LAGB = laparoscopic adjustable gastric band; RDA = recommended dietary allowance; RYGB = Roux-en Y gastric bypass; SG = sleeve gastrectomy; SQ = subcutaneous; WLS = weight loss surgery.
      R40. (2019*). Goal-directed intra- and early post-procedure fluid management should be guided by continuous noninvasive measurements to avoid over- and underhydration (Grade B, BEL 2). Once patients can tolerate orals, fluids should be consumed slowly, preferably at least 30 minutes after meals to prevent gastrointestinal symptoms, and in sufficient amounts to maintain adequate hydration (more than 1.5 liters daily) (Grade D).
      R41. (2019*). Nutrition support (enteral nutrition [EN; tube feeds] or parenteral nutrition [PN]) should be considered in bariatric surgery patients at high nutritional risk; PN should be considered in those patients who are unable to meet their needs using their gastrointestinal tract for at least 5 to 7 days with noncritical illness or 3 to 7 days with critical illness (Grade D). In patients with severe protein malnutrition and/or hypoalbuminemia, not responsive to oral or EN protein supplementation, PN should be considered (Grade D). PN formulation for patients after bariatric procedures should be hypocaloric with relatively high nitrogen (Grade D).
      R42. (2019*). Intra-/perioperative intravenous (IV) insulin is recommended for glycemic control (Grade B; BEL 2). In immediate postoperative patients with type 2 diabetes (T2D), the use of all insulin secretagogues (sulfonylureas and meglitinides), sodium-glucose cotransporter-2 inhibitors, and thiazolidinediones should be discontinued and insulin doses adjusted (due to low calorie intake) to minimize the risk for hypoglycemia (Grade D). Except for metformin and incretin-based therapies, antidiabetic medications should be withheld if there is no evidence of hyperglycemia (Grade D). Metformin and/or incretin-based therapies may be continued postoperatively in patients with T2D until prolonged clinical resolution of T2D is demonstrated by normalized glycemic targets (including fasting and postprandial blood glucose and A1C (Grade D). Subcutaneous insulin therapy, using a rapidacting insulin analogue (insulin lispro, aspart, or glulisine) before meals and a basal long-acting insulin analogue (insulin glargine, detemir, or degludec) should be used to achieve glycemic targets (140 to 180 mg/dL) in hospitalized patients not in intensive care (Grade D). In the intensive care unit (ICU), IV regular insulin as part of a standard intensive insulin therapy protocol should be used to control hyperglycemia to a 140 to 180 mg/dL blood glucose target (Grade D). Endocrinology consultation should be considered for patients with type-1 diabetes (T1D), or with T2D and uncontrolled hyperglycemia (Grade D). Once home, in patients with T2D, periodic fasting blood glucose concentrations must be determined (Grade A; BEL 1). Preprandial, 2-hour postprandial, and bedtime reflectance meter glucose (RMG; “fingerstick”) determinations, or the use of continuous glucose monitors, in the home setting is also recommended, depending on the patient’s ability to test the level of glycemic control targeted, use of oral agents or insulin, and overall care plan (Grade A; BEL 1). RMG determinations or the use of continuous glucose monitors is recommended if symptoms of hypoglycemia occur (Grade A; BEL 1).
      R43. (2013*). Patients with high perioperative risk for myocardial infarction should be managed in a telemetry-capable setting for at least the first 24 hours after a bariatric surgical procedure (Grade B; BEL 2).
      R44. (2019*). Pulmonary management includes aggressive pulmonary toilet and incentive spirometry, oxygen supplementation to avoid hypoxemia, and early institution of continuous positive airway pressure (CPAP) when clinically indicated (Grade C, BEL 3). Routine admission to an intensive care unit should not be implemented in patients solely due to the presence of severe obstructive sleep apnea provided there is adequate CPAP use (Grade D).
      R45. (2019*). Prophylaxis against deep venous thrombosis (DVT) is recommended for all patients after bariatric surgical procedures (Grade B; BEL 2). Prophylactic regimens after bariatric surgery may include sequential compression devices (Grade C; BEL 3), as well as subcutaneously administered unfractionated heparin or low-molecular-weight heparin given within 24 hours after bariatric surgery (Grade B; BEL 2). Extended chemoprophylaxis after hospital discharge should be considered for high-risk patients, such as those with history of DVT, known hypercoagulable state, or limited ambulation (Grade C, BEL 3). The use of DVT risk calculators (Grade C; BEL 3) and early ambulation are encouraged (Grade C; BEL 3). Serum anti-Xa levels should be considered to guide low-molecular-weight heparin dosing in the prophylactic range (Grade A; BEL 1). Daily fondaparinux 5 mg should be considered as a preventive option (Grade A; BEL 1).
      R46. (NEW). Respiratory distress or failure to wean from ventilatory support should prompt a diagnostic work-up for pulmonary embolus (Grade B; BEL 2).
      R47. (2019*). Patients with respiratory distress or failure to wean from ventilatory support after a bariatric procedure should prompt a standard diagnostic work-up with a particular emphasis to detect anastomotic leak (Grade D). In the clinically stable patient, computed tomography (CT) (preferred over upper-gastrointestinal (GI) studies [water-soluble contrast followed by thin barium]) may be considered to evaluate for anastomotic leaks in suspected patients (Grade C; BEL 3). Exploratory laparotomy or laparoscopy is justified and may therefore be considered in the setting of high clinical suspicion for anastomotic leaks (Grade A; BEL 1). A selected diatrizoate meglumine and diatrizoate sodium upper-GI study in the absence of abnormal signs or symptoms may be considered to identify any subclinical leaks before discharge of the patient from the hospital, but routine studies are not cost-effective (Grade C; BEL 3). C-reactive protein (CRP) and/or procalcitonin testing should be considered if a postoperative leak is suspected or the patient is at increased risk for a leak after hospital discharge (Grade B; BEL 2).
      R48. (2019*). Patients should have adequate padding at pressure points during bariatric surgery (Grade D). When rhabdomyolysis is suspected, creatine kinase (CK) levels should be determined, urine output monitored, and adequate hydration provided (Grade C; BEL 3). The risk for rhabdomyolysis increases as body mass index (BMI) increases (particularly with BMI >55 to 60 kg/m2); therefore, screening CK levels may be tested in these higher risk groups (Grade D). Excessive postoperative IV fluids should be avoided (Grade D).
      Q6. How can care be optimized 5 or more days after a bariatric procedure?
      R49. (2019*). Follow-up should be scheduled depending on the bariatric procedure performed and the severity of comorbidities (Table 9) (Grade D). Following laparoscopic adjustable gastric band procedures, frequent nutritional follow-up and band adjustments are recommended to optimize safety and achieve weight-loss targets (Grade C; BEL 3). Significant weight regain or failure to lose weight should prompt a comprehensive evaluation for (a) decreased patient adherence with lifestyle modification, (b) evaluation of medications associated with weight gain or impairment of weight loss, (c) development of maladaptive eating behaviors, (d) psychological complications, and (e) radiographic or endoscopic evaluation to assess pouch enlargement, anastomotic dilation, formation of a gastrogastric fistula among patients who underwent Rouxen- Y gastric bypass, or inadequate band restriction among patients who underwent laparoscopic adjustable gastric banding (Grade B; BEL 2). Interventions should first include dietary change, physical activity, behavioral modification with frequent follow-up, and then, if appropriate, pharmacologic therapy and/or surgical revision (Grade B; BEL 2). In those patients with or without complete resolution of their comorbidities, such as type 2 diabetes, dyslipidemia, obstructive sleep apnea or hypertension, continued surveillance and management should be guided by current clinical practice guidelines for those conditions (Grade D). Routine metabolic and nutritional monitoring is recommended after all bariatric procedures (Grade A; BEL 1).
      R50. (2013*). Patients who have undergone Roux-en-Y gastric bypass, biliopancreatic diversion with/without duodenal switch, or sleeve gastrectomy and who present with postprandial hypoglycemic symptoms that have not responded to nutritional manipulation should undergo an evaluation to differentiate noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) from factitious or iatrogenic causes, dumping syndrome, and insulinoma (Grade C; BEL 3). In patients with NIPHS, therapeutic strategies should be implemented, and include dietary changes (low-carbohydrate diet), octreotide, diazoxide, acarbose, calcium-channel antagonists, gastric restriction, and/or reversal procedures, with partial or total pancreatectomy reserved for the rare recalcitrant cases (Grade C; BEL 3). Continuous glucose monitoring may be considered in those patients with hypoglycemia syndromes after bariatric procedures (Grade C, BEL 3).
      R51. (2013*). Unless specifically contra-indicated, patients must be advised to incorporate at least some amount of physical activity, with a target of moderate aerobic physical activity that includes a minimum of 150 minutes per week and goal of 300 minutes per week, including strength training 2 to 3 times per week (Grade A; BEL 1).
      R52. (2019*). All patients should be encouraged to participate in ongoing support groups (Grade B; BEL 2), self-monitoring (Grade B; BEL 2), and/or mobile technologies (Grade B; BEL 2) to improve weight loss and cardiometabolic risks after bariatric procedures.
      R53. (2019*). Baseline and annual postoperative evaluation for vitamin D deficiency is recommended after Rouxen- Y gastric bypass (RYGB), sleeve gastrectomy, or biliopancreatic diversion without/with duodenal switch (BPD/DS) (Grade B; BEL 2). In patients who have undergone RYGB, BPD, or BPD/DS, treatment with oral calcium citrate and vitamin D (ergocalciferol [vitamin D2] or cholecalciferol [vitamin D3]) is indicated to prevent or minimize secondary hyperparathyroidism without inducing frank hypercalciuria (Grade C; BEL 3). In patients with severe vitamin D malabsorption, initial oral doses of vitamin D2 50,000 IU 1 to 3 times/weekly or D3 (minimum of 3,000 IU/day to 6,000 IU/day) should be recommended. Of note, vitamin D3 is recommended as a more potent treatment than vitamin D2 based on frequency and amount of dosing needed for repletion; however, both can be utilized (Grade B; BEL 2). Recalcitrant cases may require concurrent oral administration of calcitriol (1,25-di-hydroxyvitamin D) (Grade D). Hypophosphatemia is usually due to vitamin D deficiency, and oral phosphate supplementation should be provided for mild to moderate hypophosphatemia (1.5 to 2.5 mg/dL) (Grade D).
      R54. (2008). In patients who have had Roux-en-Y gastric bypass or biliopancreatic diversion without/with duodenal switch, bone density measurements with use of axial (spine and hip) dual-energy X-ray absorptiometry may be indicated to monitor for osteoporosis at baseline and at about 2 years (Grade D).
      R55. (2013*). Evaluation of patients for bone loss after bariatric procedures may include serum parathyroid hormone, total calcium, phosphorus, 25-hydroxyvitamin D, and 24-hour urine calcium levels (Grade C; BEL 3). Antiresorptive agents (bisphosphonates or denosumab) should only be considered in patients after bariatric procedures with osteoporosis once appropriate therapy for calcium and vitamin D insufficiency has been implemented (Grade D). If antiresorptive therapy is indicated after bariatric procedures, then intravenously administered bisphosphonates should be used (zoledronic acid, 5 mg once a year, or ibandronate, 3 mg every 3 months), as concerns exist about adequate oral absorption and potential anastomotic ulceration with orally administered bisphosphonates (Grade D). If concerns about absorption or potential anastomotic ulceration are obviated, oral bisphosphonate administration can be provided (alendronate, 70 mg/week; risedronate, 35 mg/week or 150 mg/month; or ibandronate, 150 mg/month). Alternatively, if bisphosphonates are poorly tolerated or ineffective, denosumab (60 mg subcutaneously every 6 months) may be considered, but again once appropriate therapy for calcium and vitamin D insufficiency has been implemented (Grade D).
      R56. (2013*). Management of oxalosis and calcium oxalate stones includes avoidance of dehydration (Grade D), a low-oxalate meal plan (Grade D), oral calcium (Grade B; BEL 1; downgraded due to small evidence base), and potassium citrate therapy (Grade B; BEL 1; downgraded due to small evidence base). Probiotics containing Oxalobacter formigenes may be used, as they have been shown to improve renal oxalate excretion and improve supersaturation levels (Grade C; BEL 3).
      R57. (2019*). Aggressive case finding (i.e., detecting a disorder in patients at risk) for vitamin A undernutrition may be performed in the first postoperative year after Rouxen- Y gastric bypass (RYGB) or biliopancreatic diversion without/with duodenal switch (BPD/DS) or with evidence of malnutrition due to high prevalence for this deficiency state in these settings (Grade C; BEL 3). Aggressive case finding for vitamin E and K deficiencies should be reserved for those postoperative patients demonstrating symptoms (hemolytic anemia and neuromuscular, particularly ophthalmologic, for vitamin E; excessive bleeding or bruising for vitamin K) (Grade D). When indicated, the dosing strategies for vitamin A are 5,000 IU/day for laparoscopic adjustable gastric banding (LAGB), 5,000 to 10,000 IU/day for RYGB and SG, and 10,000 IU/day for BPD/DS; for vitamin E, 15 mg/day for all procedures; and for vitamin K, 90 to 120 μg/d for LAGB, RYGB, and SG and up to 300 μg/d for BPD/DS (Grade D).
      R58. (2008*). In the presence of any established fat-soluble vitamin deficiency (vitamins A, D, E, and/or K) with, for example, hepatopathy, neuromuscular impairment, coagulopathy, or osteoporosis, or suspected essential fatty acid deficiency (symptoms include hair loss, poor wound healing, and dry scaly skin), clinical and biochemical assessments of the other fat-soluble vitamins may be considered and then supplemented if abnormally low (Grade D). In patients with suspected essential fatty acid deficiency in the setting of malabsorptive procedures, therapeutic trials with topical borage, soybean, or safflower oil may be considered due to the low risk profile, but these trials are unproven at present (Grade D).
      R59. (2019*). Anemia without evidence of blood loss warrants evaluation of nutritional deficiencies, as well as age-appropriate causes during the late post-procedure period (Grade D). Iron status should be monitored in all patients within the first 3 months after bariatric procedures, then every 3 to 6 months until 12 months, and then annually thereafter for all patients (Grade B; BEL 2). Treatment regimens include oral ferrous sulfate, fumarate, or gluconate to provide up to 150 to 200 mg of elemental iron daily (Grade A; BEL 1). Vitamin C supplementation may be added simultaneously to increase iron absorption (Grade C; BEL 3). Intravenous iron infusion (preferably with ferric gluconate or sucrose) may be needed for patients with severe intolerance to oral iron or refractory deficiency due to severe iron malabsorption (Grade D).
      R60. (2019*). Baseline and annual post–bariatric procedure evaluation for vitamin B12 deficiency should be performed in all patients (Grade B; BEL 2). More frequent aggressive case finding (e.g., every 3 months) should be performed in the first postoperative year, and then at least annually or as clinically indicated for patients who chronically use medications that exacerbate the risk of B12 deficiency: nitrous oxide, neomycin, metformin, colchicine, proton-pump inhibitors, and seizure medications (Grade B, BEL 2). Since serum B12 may not be adequate to identify B12 deficiency, consider measuring serum methylmalonic acid, with or without homocysteine, to identify a metabolic deficiency of B12 in symptomatic and asymptomatic patients and in patients with a history of B12 deficiency or pre-existing neuropathy (Grade B, BEL 2). Oral supplementation (via disintegrating tablet, sublingual, or liquid) with crystalline vitamin B12 at a dosage of 350 to 1,000 μg daily or more is recommended to maintain normal vitamin B12 levels (Grade A; BEL 1). Intranasally administered vitamin B12 may also be considered (Grade D). Parenteral (intramuscular or subcutaneous) B12 supplementation, 1,000 μg/month to 1,000 to 3,000 μg every 6 to 12 months, is indicated if B12 sufficiency cannot be maintained using oral or intranasal routes (Grade C; BEL 3).
      R61. (2013). Folic acid supplementation (400 to 800 μg/day) should be part of a routine multivitamin-multimineral preparation (Grade B; BEL 2) and must be supplemented further (1,000 μg/day) when a deficiency state is suspected (e.g., with skin, nail, or mucosal changes) or found, as well as in all women of childbearing age (800 to 1,000 μg/day) to reduce the risk of fetal neural tube defects (Grade A; BEL 1). B12 status should be assessed in patients on higher-dose folic acid supplementation (>1,000 μg/day) to detect a masked B12 deficiency state (Grade D).
      R62. (2013). Nutritional anemias resulting from malabsorptive bariatric procedures can involve deficiencies in vitamin B12, folate, protein, copper, selenium, and zinc and may be evaluated when routine aggressive case finding for iron-deficiency anemia is negative (Grade C; BEL 3).
      R63. (2013). There is insufficient evidence to support routine selenium screening or supplementation after a bariatric procedure (Grade D). However, selenium levels may be checked as part of aggressive case finding in patients with a malabsorptive bariatric surgical procedure who have unexplained anemia or fatigue, persistent diarrhea, cardiomyopathy, or metabolic bone disease (Grade C; BEL 3).
      R64. (2019*). Zinc supplementation should be included as part of a routine multivitamin-multimineral preparation with 8 to 22 mg/day to prevent a deficiency state; the amount indicated varies depending on the bariatric procedure performed, with greater amounts required for Roux-en-Y gastric bypass (RYGB) and biliopancreatic diversion without/with duodenal switch (BPD/DS) (Grade C; BEL 3). Routine aggressive case finding for zinc deficiency utilizing serum and plasma zinc determinations should be performed after malabsorptive bariatric surgical procedures (RYGB and BPD/DS) (Grade C; BEL 3), and zinc deficiency should also be considered in any patient after a bariatric procedure with chronic diarrhea, hair loss, pica, significant dysgeusia, or in male patients with unexplained hypogonadism or erectile dysfunction (Grade D). Treatment of zinc deficiency should target normal biochemical levels with 1 mg/day copper also supplemented for every 8 to 15 mg/day elemental zinc provided (Grade D).
      R65. (2019*). Routine aggressive case finding for copper deficiency using serum copper and ceruloplasmin may be considered for all patients who have undergone Rouxen- Y gastric bypass (RYGB) or biliopancreatic diversion without/with duodenal switch (BPD/DS) at least annually, even in the absence of clinical signs or symptoms of deficiency (Grade C, BEL 3), but especially in patients who are experiencing anemia, neutropenia, myeloneuropathy, or impaired wound healing (Grade D). Copper supplementation (2 mg/day) should be included as part of a routine multivitamin-multimineral preparation; further supplementation varies depending on the surgical procedure performed, with greater amounts required for patients who have had RYGB or BPD/DS (Grade D). In severe deficiency, treatment can be initiated with IV copper (3 to 4 mg/day) for 6 days (Grade D). Subsequent treatment of severe deficiency, or treatment of mild-to-moderate deficiency, can usually be achieved with oral copper sulfate or gluconate 3 to 8 mg/day until levels normalize and symptoms resolve (Grade D). Patients being treated for zinc deficiency or using supplemental zinc for hair loss should receive 1 mg of copper for each 8 to 15 mg of elemental zinc, since zinc replacement can cause copper deficiency (Grade C; BEL 3). Copper gluconate or sulfate is the recommended source of copper for supplementation (Grade C; BEL 3).
      R66. (2019*). Thiamine (vitamin B1) supplementation above the recommended dietary allowance (RDA) is suggested to prevent thiamine deficiency (Grade D). Routine thiamine screening may be considered following bariatric procedures (Grade C; BEL 3). Aggressive case finding for thiamine deficiency and/or empiric thiamine supplementation is indicated for high-risk postprocedure patients, such as those with established preprocedure risk factors for thiamine deficiency, females, African Americans, patients not attending a nutritional clinic, patients with gastrointestinal symptoms, patients with heart failure, protracted vomiting, parenteral nutrition, excessive alcohol use, neuropathy or encephalopathy (Grade C; BEL 3), or small intestinal bacterial overgrowth (SIBO) (Grade C; BEL 3). All post-WLS patients should take at least 12 mg thiamine daily (Grade C; BEL 3). A 50-100 mg daily dose of thiamine from a B-complex supplement or high-potency multivitamin may be needed to maintain sufficient blood levels of thiamine and prevent thiamine deficiency in some patients (Grade D). Patients with severe thiamine deficiency (suspected or established) should be treated with intravenous (IV) (or intramuscular if IV access is not available) thiamine, 500 mg/day, for 3 to 5 days, followed by 250 mg/day for 3 to 5 days or until resolution of symptoms, and then to consider treatment with 100 mg/day, orally, usually indefinitely or until risk factors have resolved (Grade C; BEL 3). Mild deficiency can be treated with IV thiamine, 100 mg/day, for 7 to 14 days (Grade C; BEL 3). In patients with recalcitrant or recurrent thiamine deficiency with one of the above risks, the addition of antibiotics for SIBO should be considered (Grade C; BEL 3).
      R67. (NEW). Commercial products that are used for micronutrient supplementation need to be discussed with a health-care professional familiar with dietary supplements, since many products are adulterated and/or mislabeled (Grade D).
      R68. (2013*). Lipid levels and the need for lipid-lowering medications should be periodically evaluated (Grade D). The effect of weight loss on dyslipidemia is variable and incomplete; therefore, lipid-lowering medications should not be stopped unless clearly indicated (Grade C; BEL 3).
      R69. (2019*). The need for antihypertensive medications should be evaluated repeatedly and frequently during the active phase of weight loss (Grade D). Because the effect of weight loss on blood pressure is variable, incomplete, and at times transient, antihypertensive medications should not be stopped unless clearly indicated; however, dosages may need to be titrated downward as blood pressure improves (Grade D).
      R70. (NEW). Close attention to dosing of diabetes medication is recommended for those having had sleeve gastrectomy, Roux-en-Y gastric bypass, or biliopancreatic diversion without/with duodenal switch, since these patients generally have dosing reduced in the early postoperative period, whereas those having had laparoscopic adjustable gastric banding require significant weight loss before dosing must be reduced (Grade B; BEL 2). Patients with type 2 diabetes who had their diabetes medication stopped after bariatric procedures must be monitored closely for recurrence of hyperglycemia, particularly with weight regain or suboptimal weight loss (Grade B; BEL 2).
      R71. (NEW). In patients on thyroid hormone replacement or supplementation, thyroid-stimulating hormone (TSH) levels must be monitored after bariatric procedures and medication dosing adjusted, as dose reductions are more likely with weight loss but can increase with malabsorption (Grade B; BEL 2). Oral liquid forms of levothyroxine may be considered in those patients who have difficulty swallowing tablets after bariatric procedures (Grade D). Oral liquid or softgel forms of levothyroxine may be considered in patients with significant malabsorption in whom adequate TSH suppression to normal ranges is difficult after bariatric procedures (Grade C; BEL 3).
      R72. (2019*). Persistent and severe gastrointestinal (GI) symptoms (e.g., nausea, vomiting, abdominal pain, diarrhea, and constipation) warrant evaluation utilizing a pertinent history and physical exam, appropriate laboratory testing, and imaging (most commonly computerized tomography and/or upper GI series) (Grade C; BEL 3). Upper endoscopy with small-bowel biopsies and aspirates remains the gold standard and should be part of the evaluation of celiac disease and bacterial overgrowth in patients who have had a bariatric procedure (Grade C; BEL 3). Screening with a stool specimen should be obtained if the presence of Clostridium difficile colitis is suspected (Grade C; BEL 3). Persistent steatorrhea after BPD without/with DS should prompt evaluation for nutrient deficiencies (Grade C; BEL 3).
      R73. (NEW). Patients with de novo gastroesophageal reflux and severe symptoms after sleeve gastrectomy should be treated with proton-pump inhibitor therapy, and those recalcitrant to medical therapy considered for conversion to Roux-en-Y gastric bypass (Grade C; BEL 3).
      R74. (2019*). Nonsteroidal anti-inflammatory drugs should be avoided after bariatric procedures, if possible, because they (and steroids to a lesser extent) have been implicated in the development of anastomotic ulcerations, perforations, and leaks (Grade C; BEL 3); ideally, alternative pain medication should be identified before the bariatric procedure (Grade D). If the use of nonsteroidal anti-inflammatory drugs is unavoidable, then the use of protonpump inhibitors may be considered (Grade C; BEL 3).
      R75. (2019*). Endoscopy is safe and should be the preferred procedure to evaluate gastrointestinal (GI) symptoms suggestive of stricture or foreign body (e.g., suture or staple), as it can be both diagnostic and therapeutic (e.g., endoscopic dilation or foreign body removal) (Grade C; BEL 3). Endoscopy may also be used for Helicobacter pylori testing as a possible contributor to persistent GI symptoms after bariatric procedures (Grade D).
      R76. (NEW). Anastomotic ulcers after bariatric procedures should be treated with proton-pump inhibitors; prophylactic therapy with proton-pump inhibitors should be considered for 90 days to 1 year, depending on risk (Grade B; BEL 2). H2 receptor blockers and sucralfate may also be considered for postprocedure anastomotic ulcers, and if Helicobacter pylori is identified, triple therapy, including antibiotics, bismuth, and proton-pump inhibitors, may be used (Grade C; BEL 3).
      R77. (2013*). Patients who have undergone Roux-en-Y gastric bypass with a nonpartitioned stomach and developed a gastrogastric fistula with symptoms (e.g., weight regain, marginal ulcer, stricture, or gastroesophageal reflux) may be considered for a revisional procedure (Grade C; BEL 3).
      R78. (2019*). Persistent vomiting, regurgitation, and upper-gastrointestinal (GI) obstruction after laparoscopic adjustable gastric banding (LAGB) should be treated with immediate removal of fluid from the adjustable band (Grade D). Persistent symptoms of gastroesophageal reflux, regurgitation, chronic cough, or recurrent aspiration pneumonia in a patient after LAGB raise concern for band slippage, esophageal dilation, and, in some cases, erosion, and should prompt evaluation of the patient with upper-GI endoscopy or fluoroscopy (Grade C; BEL 3), immediate referral to a bariatric surgeon, and depending on the clinical course, consideration of conversion to sleeve gastrectomy or Roux-en-Y gastric bypass (Grade D).
      R79. (2019*). Ultrasound should be used to evaluate patients with right upper-quadrant pain for cholecystitis (Grade D). Patients who undergo sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), or biliopancreatic diversion without/with duodenal switch (BPD/DS) are at increased risk for cholelithiasis due to rapid weight loss, and oral administration of ursodeoxycholic acid is recommended: 500 mg once daily for SG and 300 mg twice a day for RYGB or BPD/DS (Grade A; BEL 1). In asymptomatic patients with known gallstones and a history of RYGB or BPD/DS, prophylactic cholecystectomy may be considered to avoid choledocholithiasis, since traditional endoscopic retrograde cholangiopancreatography can no longer be performed in these patients. Otherwise, cholecystectomy should be reserved for patients with symptomatic biliary disease due to a generally low incidence of biliary complications (Grade B; BEL 2).
      R80. (2013*). Although uncommon, suspected small intestinal bacterial overgrowth in the biliopancreatic limb after biliopancreatic diversion without/with duodenal switch may be treated empirically with metronidazole or rifaximin (Grade C; BEL 3). For antibiotic-resistant cases of bacterial overgrowth, probiotic therapy with Lactobacillus plantarum 299v and/or Lactobacillus GG may be considered (Grade D). Thiamine deficiency may be suspected in patients with small intestinal bacterial overgrowth after bariatric procedures, especially when gut dysmotility occurs (Grade C; BEL 3).
      R81. (2008*). Definitive repair of asymptomatic abdominal wall hernias can be deferred until weight loss has stabilized and nutritional status has improved to allow for adequate wound healing (12 to 18 months after bariatric surgery) (Grade D). Symptomatic hernias that occur after bariatric surgery may require prompt surgical evaluation (Grade C; BEL 3). Patients with sudden-onset of severe cramping, periumbilical pain, or recurrent episodes of severe abdominal pain any time after bariatric surgery should be evaluated with an abdominal and pelvic computerized tomography (CT) scan to exclude the potentially life-threatening complication of a closed-loop bowel obstruction (Grade D). Exploratory laparotomy or laparoscopy is indicated in patients who are suspected of having an internal hernia because this complication can be missed with upper gastrointestinal X-ray studies and CT scans (Grade C; BEL 3).
      R82. (2013*). Body-contouring surgery may be performed after bariatric procedures to manage excess tissue that impairs hygiene, causes discomfort, and is disfiguring (Grade C; BEL 3). Body-contouring surgery is best pursued after weight loss has stabilized (12 to 18 months after bariatric surgery) (Grade D).
      Adapted from Surg Obes Rel Dis.13, Parrott J, et al American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients, 727-741, 2017, with permission from Elsevier.
      Adapted from Surg Obes Rel Dis.13, Parrott J, et al American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients, 727-741, 2017, with permission from Elsevier.
      Q7. What are the criteria for hospital admission after a bariatric procedure?
      R83. (2013). Severe malnutrition or hypoglycemia after a bariatric procedure should prompt hospital admission (Grade D). The initiation and formulation of enteral (tube feeding) or parenteral nutrition should be guided by current clinical practice guidelines (Grade D). Hospital admission is required for the management of gastrointestinal (GI) complications after bariatric procedures in clinically unstable patients (Grade D). Surgical management should be pursued for GI complications not amenable or responsive to medical therapy (Grade D). However, if not dehydrated, patients may undergo endoscopic stomal dilation for stricture as an outpatient procedure (Grade D).
      R84. (2008). Revision of a bariatric surgical procedure can be recommended when serious complications related to previous bariatric surgery cannot be managed medically (Grade C; BEL 3).
      R85. (2008). Reversal of a bariatric surgical procedure is recommended when serious complications related to previous bariatric surgery cannot be managed medically and are not amenable to surgical revision (Grade D).

      UPDATED EVIDENCE BASE FOR 2019

      This evidence base pertains to the 7 questions and 85 updated numbered recommendations. There are 858 citations, of which 81% were published in 2013 or later, with 81 (9.4%) EL 1, 562 (65.5%) EL 2, 72 (8.4%) EL 3, and 143 (16.7%) EL 4, compared with 32 (7.9%) EL 1, 129 (32%) EL 2, 173 (43%) EL 3, and 69 (17.1%) EL 4 in the 2013 AACE/TOS/ASMBS CPG and 13 (1.7%) EL 1, 112 (14.4%) EL 2, 460 (59.2%) EL 3, and 192 (24.7%) EL 4 in the 2008 AACE/TOS/ASMBS CPG. There is a relatively high proportion (75%) of strong (EL 1 and 2) studies, compared with 40% in the 2013 AACE/TOS/ASMBS CPG and only 16% in the 2008 AACE/TOS/ASMBS CPG. The primary evidence base, supporting tables, and unrevised recommendations for general information are not provided in this document and may be found in the 2008 (
      • Mechanick J.I.
      • Kushner R.F.
      • Sugerman H.J.
      • et al.
      American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery medical guidelines for clinical practice for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient.
      ) and 2013 AACE/TOS/ASMBS CPG (
      • Mechanick J.I.
      • Youdim A.
      • Jones D.B.
      • et al.
      Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient--2013 update: cosponsored by American Association of Clinical Endocrinologists, the Obesity Society, and American Society for Metabolic & Bariatric Surgery.
      ). Readers are strongly encouraged to review these past CPGs to place the updated explanations and references into better context. The technical evidence ratings for these updated references are found in the reference section of this document, appended at the end of each citation.
      Q1. Which patients should be offered bariatric procedures?
      R1. (2019*). Mortality rates, the risk and prevalence of ORCs conferring disease morbidity, and social costs of obesity are highest in those patients with class-III severe obesity (i.e., BMI ≥40 kg/m2) (
      • Calle E.E.
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      ,
      • Kitahara C.M.
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      Association between class III obesity (BMI of 40-59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.
      ,
      • Sjöström L.
      • Narbro K.
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      • et al.
      Effects of bariatric surgery on mortality in Swedish obese subjects.
      ). The evidence base for recommending bariatric surgery for patients with BMI ≥40 kg/m2 without co-existing medical problems or severe ORC is supported by recent studies demonstrating benefit with respect to reduced mortality (
      • Arterburn D.E.
      • Olsen M.K.
      • Smith V.A.
      • et al.
      Association between bariatric surgery and long-term survival.
      ,
      • Kwok C.S.
      • Pradhan A.
      • Khan M.A.
      • et al.
      Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.
      ,
      • Sjöström L.
      • Narbro K.
      • Sjöström C.D.
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      Effects of bariatric surgery on mortality in Swedish obese subjects.
      ,
      • Adams T.D.
      • Gress R.E.
      • Smith S.C.
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      Long-term mortality after gastric bypass surgery.
      ,
      • Flum D.R.
      • Dellinger E.P.
      Impact of gastric bypass operation on survival: a population-based analysis.
      ,
      • Maciejewski M.L.
      • Livingston E.H.
      • Smith V.A.
      • et al.
      Survival among high-risk patients after bariatric surgery.
      ,
      • Pontiroli A.E.
      • Morabito A.
      Long-term prevention of mortality in morbid obesity through bariatric surgery. a systematic review and meta-analysis of trials performed with gastric banding and gastric bypass.
      ,
      • Buchwald H.
      • Rudser K.D.
      • Williams S.E.
      • Michalek V.N.
      • Vagasky J.
      • Connett J.E.
      Overall mortality, incremental life expectancy, and cause of death at 25 years in the program on the surgical control of the hyperlipidemias.
      ), improvements in cardiovascular risk factors (
      • Mingrone G.
      • Panunzi S.
      • De Gaetano A.
      • et al.
      Bariatric-metabolic surgery versus conventional medical treatment in obese patients with type 2 diabetes: 5 year follow-up of an open-label, singlecentre, randomised controlled trial.
      ,
      • Kwok C.S.
      • Pradhan A.
      • Khan M.A.
      • et al.
      Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.
      ,
      • Hofsø D.
      • Nordstrand N.
      • Johnson L.K.
      • et al.
      Obesity-related cardiovascular risk factors after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention.
      ), reduced rates of some cancers (
      • Sjöström L.
      • Gummesson A.
      • Sjöström C.D.
      • et al.
      Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial.
      ,
      • Adams T.D.
      • Stroup A.M.
      • Gress R.E.
      • et al.
      Cancer incidence and mortality after gastric bypass surgery.
      ,
      • Christou N.V.
      • Lieberman M.
      • Sampalis F.
      • Sampalis J.S.
      Bariatric surgery reduces cancer risk in morbidly obese patients.
      ), substantial weight loss that is persistent in most patients (
      • Kwok C.S.
      • Pradhan A.
      • Khan M.A.
      • et al.
      Bariatric surgery and its impact on cardiovascular disease and mortality: a systematic review and meta-analysis.
      ,
      • Sjöström L.
      • Narbro K.
      • Sjöström C.D.
      • et al.
      Effects of bariatric surgery on mortality in Swedish obese subjects.
      ,
      • Pontiroli A.E.
      • Morabito A.
      Long-term prevention of mortality in morbid obesity through bariatric surgery. a systematic review and meta-analysis of trials performed with gastric banding and gastric bypass.
      ,
      • Buchwald H.
      • Rudser K.D.
      • Williams S.E.
      • Michalek V.N.
      • Vagasky J.
      • Connett J.E.
      Overall mortality, incremental life expectancy, and cause of death at 25 years in the program on the surgical control of the hyperlipidemias.
      ,
      • Padwal R.
      • Klarenbach S.
      • Wiebe N.
      • et al.
      Bariatric surgery: a systematic review and network meta-analysis of randomized trials.
      ,
      • Garb J.
      • Welch G.
      • Zagarins S.
      • Kuhn J.
      • Romanelli J.
      Bariatric surgery for the treatment of morbid obesity: a meta-analysis of weight loss outcomes for laparoscopic adjustable gastric banding and laparoscopic gastric bypass.
      ,

      Valezi AC, Mali Junior J, de Menezes MA, de Brito EM, de Souza SA. Weight loss outcome after silastic ring Roux-en-Y gastric bypass: 8 years of follow-up. Obes Surg. 2010;20:1491-1495.

      ,
      • Toouli J.
      • Kow L.
      • Ramos A.C.
      • et al.
      International multicenter study of safety and effectiveness of Swedish Adjustable Gastric Band in 1-, 3-, and 5-year follow-up cohorts.
      ), diabetes prevention (
      • Carlsson L.M.
      • Peltonen M.
      • Ahlin S.
      • et al.
      Bariatric surgery and prevention of type 2 diabetes in Swedish obese subjects.
      ,
      • Booth H.
      • Khan O.
      • Prevost T.
      • et al.
      Incidence of type 2 diabetes after bariatric surgery: population-based matched cohort study.
      ,
      • Hofsø D.
      • Jenssen T.
      • Bollerslev J.
      • et al.
      Beta cell function after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention.
      ), improved pulmonary function (
      • Lumachi F.
      • Marzano B.
      • Fanti G.
      • Basso S.M.
      • Mazza F.
      • Chiara G.B.
      Hypoxemia and hypoventilation syndrome improvement after laparoscopic bariatric surgery in patients with morbid obesity.
      ), and better mobility and quality of life (
      • Tarride J.E.
      • Breau R.
      • Sharma A.M.
      • et al.
      The effect of bariatric surgery on mobility, health-related quality of life, healthcare resource utilization, and employment status.
      ,
      • Ryder J.R.
      • Edwards N.M.
      • Gupta R.
      • et al.
      Changes in functional mobility and musculoskeletal pain after bariatric surgery in teens with severe obesity: teen-longitudinal assessment of bariatric surgery (LABS) study.
      ,
      • Vincent H.K.
      • Ben-David K.
      • Conrad B.P.
      • Lamb K.M.
      • Seay A.N.
      • Vincent K.R.
      Rapid changes in gait, musculoskeletal pain, and quality of life after bariatric surgery.
      ). Currently, the WHO classification scheme for obesity determines diagnostic and therapeutic management based on BMI. However, BMI is a surrogate measure of adipose tissue mass, is confounded by ethnic differences and aspects of body composition (
      • Ashwell M.
      • Gunn P.
      • Gibson S.
      Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis.
      ,
      • Pories W.J.
      • Dohm L.G.
      • Mansfield C.J.
      Beyond the BMI: the search for better guidelines for bariatric surgery.
      ,
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