Surgical Endoscopy (2020) 34:2332–2358 and Other Interventional Techniques https://doi.org/10.1007/s00464-020-07555-y GUIDELINES Clinical practice guidelines of the European Association for Endoscopic Surgery (EAES) on bariatric surgery: update 2020 endorsed by IFSO‑EC, EASO and ESPCOP Nicola Di Lorenzo1 · Stavros A. Antoniou2,3 · Rachel L. Batterham4,5 · Luca Busetto6 · Daniela Godoroja7 · Angelo Iossa8 · Francesco M. Carrano9 · Ferdinando Agresta10 · Isaias Alarçon11 · Carmil Azran12 · Nicole Bouvy13 · Carmen Balaguè Ponz14 · Maura Buza15 · Catalin Copaescu15 · Maurizio De Luca16 · Dror Dicker17 · Angelo Di Vincenzo6 · Daniel M. Felsenreich18 · Nader K. Francis19 · Martin Fried20 · Berta Gonzalo Prats14 · David Goitein21,22 · Jason C. G. Halford23 · Jitka Herlesova20 · Marina Kalogridaki24 · Hans Ket25 · Salvador Morales‑Conde11 · Giacomo Piatto16 · Gerhard Prager18 · Suzanne Pruijssers13 · Andrea Pucci4,5 · Shlomi Rayman21,22 · Eugenia Romano23 · Sergi Sanchez‑Cordero26 · Ramon Vilallonga27 · Gianfranco Silecchia8 Received: 24 February 2020 / Accepted: 7 April 2020 / Published online: 23 April 2020 © The Author(s) 2020 Abstract Background Surgery for obesity and metabolic diseases has been evolved in the light of new scientific evidence, long-term outcomes and accumulated experience. EAES has sponsored an update of previous guidelines on bariatric surgery. Methods A multidisciplinary group of bariatric surgeons, obesity physicians, nutritional experts, psychologists, anesthetists and a patient representative comprised the guideline development panel. Development and reporting conformed to GRADE guidelines and AGREE II standards. Results Systematic review of databases, record selection, data extraction and synthesis, evidence appraisal and evidence-to- decision frameworks were developed for 42 key questions in the domains Indication; Preoperative work-up; Perioperative management; Non-bypass, bypass and one-anastomosis procedures; Revisional surgery; Postoperative care; and Investiga- tional procedures. A total of 36 recommendations and position statements were formed through a modified Delphi procedure. Disclaimer This clinical practice guideline has been developed in time. The information in the guideline should not be relied under the auspice of the European Association for Endoscopic upon as being complete or accurate, nor should it be considered Surgery (EAES). It is intended to be used primarily by health as inclusive of all proper treatments or methods of care or as a professionals (e.g. surgeons, anesthetists, physicians) and to statement of the standard of care. With the rapid development assist in making informed clinical decisions on diagnostic of scientific knowledge, new evidence may emerge between measures and therapeutic management. It is also intended to the time the guideline is developed and when it is published inform individual practice of allied health professionals (e.g. or read. The guideline is not continually updated and may not surgical nurses, dietitians, physical rehabilitation therapists, reflect the most recent evidence. The guideline addresses only psychologists); to inform strategic planning and resource the topics specifically identified therein and is not applicable management by healthcare authorities (e.g. regional and national to other interventions, diseases, or stages of diseases. This authorities, healthcare institutions, hospital administration guideline does not mandate any particular course of medical authorities); and to inform patients wishing to obtain an care. Further, the guideline is not intended to substitute the overview of the condition of interest and its management. The independent professional judgment of the treating provider, use of recommendations contained herein must be informed by as the guideline does not necessarily account for individual supporting evidence accompanying each recommendation and variation among patients. Even if evidence on a topic suggests a by research evidence that might not have been published by the specific diagnostic and/or treatment action, users and especially time of writing the present document. Users must thus base their health professionals may need to decide against the suggested or actions informed by newly published evidence at any given point recommended action in view of circumstances related to patient values, preferences, comorbidities and disease characteristics; Electronic supplementary material The online version of this available human, monetary and material resources; and article (https​://doi.org/10.1007/s0046​4-020-07555​-y) contains healthcare infrastructures. EAES provides this guideline on supplementary material, which is available to authorized users. an “as is” basis, and makes no warranty, express or implied, regarding the guideline. Extended author information available on the last page of the article 13 Vol:.(1234567890) Surgical Endoscopy (2020) 34:2332–2358 2333 Conclusion This document summarizes the latest evidence on bariatric surgery through state-of-the art guideline develop- ment, aiming to facilitate evidence-based clinical decisions. Keywords Bariatric surgery · Obesity · Guidelines · EAES · GRADE · AGREE II Preamble Importantly, laparoscopic surgery is now considered the gold standard approach for bariatric surgery. Under consid- It has been 14 years since EAES has launched the 2004 eration of the above, these guidelines focus exclusively on guidelines on obesity surgery. A lot has changed in the field minimally invasive bariatric surgery and common surgical since then. “Historical” techniques developed by the pio- techniques. Techniques which are now considered obsolete, neers of bariatric surgery were virtually abandoned (e.g. ver- although properly addressed in the previous guidelines, are tical gastroplasty). Plenty of innovations were added to the not included in this update. Furthermore, the following top- armamentarium of healthcare professionals for the operative ics are not addressed herein: modified laparoscopy (natural and perioperative management of bariatric patients. Sleeve orifice transluminal, single-incision and robotic surgery), gastrectomy, although considered experimental in 2004, intragastric balloons, the impact of emerging technologies has become the most common bariatric procedure. Most (3-D, fluorescence, hybrid) and pure metabolic surgery recent techniques, such as gastric plication, one-anastomosis (without the obesity parameter). bypass and endoluminal procedures are gaining increasing Former standards of clinical guidance development, attention. Reiterative (redo) surgery has gained the interest although of quality at the time, were replaced by the most of several bariatric surgeons, although clear indications and evidence-based development and reporting standards sum- even a common definition are lacking. marized by the GRADE methodology and AGREE II guidelines. The support of the EAES Guideline Subcom- for a range of chronic diseases including type 2 diabetes, mittee is hereto commended. cardiovascular diseases and cancer [2]. The complex treatment of obesity and its comorbidi- ties requires multidisciplinary integration. To this end, we History invited the participation of European organizations involved in the research and management of obesity. The European The first guidelines endorsing surgery for the management of Chapter of the International Federation for the Surgery of morbid obesity were published in 1991 by the US National Obesity and Metabolic Disorders (IFSO-EC), the European Institutes of Health (NIH) [3]. After this first regulatory Association for the Study of Obesity (EASO) and the Euro- act, several international guidelines and consensus projects pean Society for the Peri-operative Care of the Obese Patient recommended bariatric surgery as an effective treatment of (ESPCOP) joined their forces with EAES to produce high weight loss and obesity-related comorbidities. quality work. Their representatives carried a wide variety of After the introduction of laparoscopic bariatric surgery, competencies (psychologists, obesity physicians, nutritional EAES and the Society of American Gastrointestinal and experts, anesthetists, laparoscopic surgeons) and comprised Endoscopic Surgeons (SAGES) launched clinical prac- a concerted multidisciplinary panel. This is the first guide- tice guidelines in 2004 and 2008, respectively [4, 5]. The line with active involvement of a patient representative from “Interdisciplinary European Guidelines” on surgery for the EASO patient task force. severe obesity were published in 2008, and updated in 2014 Upon completion of the guideline manuscript, 2 promi- through an expert-based consensus process [6, 7]. nent experts in bariatric surgery from outside Europe were invited to appraise the work against AGREE II criteria and Rationale and objective provided their assessment with the AGREE II tool. Finally, we are obligated to deeply thank all those who The growing burden of obesity in both industrialized and have contributed to this project, which we hope will con- non-industrialized countries [2], the recognition of obesity tribute to the quality of healthcare in bariatric patients in as a disease in 2013 by the American Medical Association Europe. and other regulatory bodies [8], the ever-increasing research Nicola Di Lorenzo & Gianfranco Silecchia evidence in the field and the lack of recent clinical guidance, Content Coordinators mandate an urgent need to incorporate latest evidence into Obesity is a multifactorial disease caused by a combina- clinical practice guidelines. EAES recognized this need and tion of genetic, environment and metabolic factors [1]. From decided to sponsor the present update, which ultimately aims a public health perspective, obesity is a major risk factor to inform healthcare in bariatric patients. 13 2334 Surgical Endoscopy (2020) 34:2332–2358 Where do these guidelines apply? guideline development and reporting standards [9, 10]. Insti- tutional review board approval and written consent were not These guidelines apply to adult (age > 18) patients with required. The systematic review and synthesis of evidence body mass index (BMI) > 35 kg/m2 who are considered fit conformed to PRISMA and MOOSE reporting standards, as for surgery and with no contraindications to laparoscopic appropriate [11, 12]. surgery, unless otherwise indicated. They do not apply to the pediatric population. Healthcare systems, infrastructures, Guideline development group human and financial resources across European countries were considered upon developing these guidelines. There- The steering group consisted of bariatric surgeons, members fore, they are primarily intended to be applicable in Euro- of the EAES Consensus & Guideline Subcommittee and a pean countries, although some recommendations might be GRADE methodologist [13]. The panel was comprised of applicable to other regions with modifications. bariatric surgeons, obesity physicians, nutritional experts, psychologists, anesthetists and a patient representative Who are the target users? (“Appendix”). The present guidelines may be used by healthcare profes- Topics sionals, including bariatric surgeons, laparoscopic surgeons, obesity physicians, anesthetists, general practitioners, nutri- PICO (Patient, Intervention, Comparator, Outcomes) ques- tional experts, psychologists, obstetrics and gynecologists, tions were organized into seven domains: anesthetic and intensive care unit staff; and may be used as a reference to policymakers, such as European and national 1. Indication for surgery. authorities, healthcare administrators and health insurance 2. Preoperative work-up. providers, under consideration that the external validity may 3. Perioperative management. vary across countries, regions and healthcare institutions. 4. Bariatric procedures. 5. Revisional surgery. How long are these guidelines valid for? 6. Postoperative care. 7. Investigational procedures. In view of current and ongoing research in the field, these guidelines are valid from publication up to December 2024. A full list of PICO questions can be found in Supplemen- Target users are instructed to monitor upcoming research tary file 2. (research published from November 2018 onwards) which might provide evidence further supporting or even negating Systematic review recommendations provided herein. For further information, see Disclaimer. The literature search was confined from 2005 onwards to capture the most pertinent evidence under consideration of Update and monitoring advances in surgical techniques, operative equipment and accumulated surgical experience, and to serve as an update The content coordinators will monitor the literature and will of previous EAES guidelines [4]. The last search was run in recommend an update of these guidelines in 2023, unless November 2018. The search summary and the search syntaxes developments in the field and emerging evidence will sug- are provided in Supplementary files 3 and 4. PRISMA flow gest an earlier or later update. charts of record selection are provided in Supplementary file 5. A web-based survey of EAES, IFSO-EC, EASO and We considered meta-analyses of randomized controlled ESPCOP is planned to be launched in October 2021 to trials (RCTs), meta-analyses of cohort studies, or individual assess guidelines use among healthcare professionals and RCTs and cohort studies addressing similar PICO frameworks collect feedback on implementation barriers. to those of the predefined questions. Overarching inclusion cri- teria across PICO questions were adult patients (age > 18 years) with body mass index > 35 kg/m2 (unless otherwise indicated) Material and methods and laparoscopic surgery (in relevant topic domains). Studies addressing bariatric procedures were considered for recom- Please see Supplementary file 1 for a detailed report of the mendation only if they provided data on weight loss with a methodology. follow-up of at least 5 years. Animal studies, studies on pedi- This guideline was developed in accordance with the atric patients and on robotic or open surgery were discarded. GRADE methodology and complied with AGREE II A total of 65 systematic reviews were performed. 13 Surgical Endoscopy (2020) 34:2332–2358 2335 Evidence synthesis subjected to a web-based Delphi process involving all panel members, using PanelVoice 2.0 add-on to GRADEpro. In the presence of a recent meta-analysis in the context of Three Delphi rounds took place overall. interest, summary effect measures and interval estimates, and risk of bias parameters were considered for assessment Survey of the quality of evidence as per GRADE methodology [9, 14]. If no recent meta-analysis was available, we searched Members of participating societies were surveyed to inves- for relevant RCTs and/or cohort studies and we extracted tigate the applicability of recommendations to their prac- summary data [15, 16]. We performed pairwise meta-anal- tice. Further, attendees of the ­27th International Congress of yses using a fixed or random-effects model, as appropriate. EAES were invited to participate in an on-site survey using a For adjustable gastric banding, we performed proportion smartphone application in a dedicated session. Results of the meta-analysis to summarize the incidence of related com- online survey are provided in Supplementary file 6. plications and reoperations. Forest plots and funnel plots (where available) can be provided by the authors upon rea- Appraisal sonable request. We generated evidence tables, summarizing judgments The full guideline in its final version was reviewed by 2 on study design, risk of bias, inconsistency, indirectness, prominent obesity surgeons and was appraised using the imprecision and the overall quality of evidence on each out- AGREE II tool. Their appraisal can be found in Supple- come of interest [17, 18]. mentary file 7. Evidence‑to‑decision framework Results Predefined parameters were taken into account to formu- late recommendations. More specifically, importance of the A summary list of recommendations can be found in Table 1. problem, desirable/undesirable effects and their balance, the The decision trees depicted in Figs. 1, 2, 3, 4, and 5 sche- certainty (quality) of evidence, patient values and prefer- matically summarize the recommendations. ences, acceptability to key stakeholders, cost of implemen- tation and feasibility of incorporating the intervention into practice were considered through research evidence, where Topic 1: indication for bariatric surgery available, or through panel consensus [19]. Under considera- tion of these parameters, the panel provided for each PICO Bariatric surgery versus medical management question: for morbid obesity • A strong recommendation for the intervention or the comparator, Laparoscopic bariatric surgery should be considered for patients with BMI ≥ 40 kg/m2 and for patients with BMI ≥ 35–40 kg/m2 • A conditional recommendation for the intervention or the with associated comorbidities that are expected to improve with comparator, or weight loss • No recommendation (conditional recommendation for Strong recommendation either the intervention or the comparator) [19]. Laparoscopic bariatric/metabolic surgery should be considered for patients with ≥ BMI 30–35 kg/m2 and type 2 diabetes and/or arterial hypertension with poor control despite optimal medical If no recommendation could be formulated on a PICO therapy question, the panel had the option to draft a position state- Strong recommendation ment. Position statements reflect the opinion of the panel, are not necessarily based upon research evidence and should Justification not be considered formal, evidence-based recommendations. We used the GRADEpro GDT software (enterprise ver- Fifteen RCTs were identified comparing weight loss after bari- sion) for generation of evidence tables, development of rec- atric surgery or medical therapy (5 reporting on RYGB, 3 on ommendations and Delphi process. [20]. LAGB and the rest on mixed patient populations undergoing sleeve gastrectomy, BPD/DS, sleeve gastrectomy and/or band- Delphi process ing) [21–35]. Random-effects meta-analysis was performed due to conceptual heterogeneity in operative interventions and non- The recommendation drafts, along with background evi- operative management. A RCT performed in a mixed population dence and judgements on the above parameters, were 13 2336 Surgical Endoscopy (2020) 34:2332–2358 (RYGB, sleeve gastrectomy, banding) reported a weighted mean seven studies with 255,435 patients, found similar results difference (WMD) of 53% (95% confidence interval, CI, 42% [38]. Multivariable analysis of a registry cohort found H. to 63%) excess weight loss (EWL) compared to non-operative pylori status to be the most important independent predictor management [34]. Similarly, meta-analysis of 4 RCTs suggested of marginal ulceration in patients undergoing RYGB, but it a WMD of post-intervention weight of − 19 kg (95% CI − 27 had little impact on the outcome of other bariatric operations to − 12) in favor of bariatric surgery, associated with moderate [39]. Indirectness of the evidence and imprecision of effect and low certainty of the evidence, respectively. These data lend estimates were major parameters to judge the quality of evi- support to the results of the Swedish Obese Subjects study, a dence, which was very low across outcomes (Supplementary large cohort study comparing bariatric surgery versus medical Table S2). This is reflected in a conditional recommendation management in the very long term [36]. for either routine eradication or alternative practice. There were small or non-important differences for sev- eral metabolic surrogates. However, there was very strong Preoperative diet consultation versus standard care association between bariatric surgery and type II diabetes in patients undergoing bariatric surgery (T2DM) resolution (odds ratio, OR, 29, 95% CI 13 to 67) and moderate reduction of systolic blood pressure. These effects were observed even in RCTs enrolling patients with Preoperative dietitian consultation should be considered for patients undergoing bariatric surgery BMI 30–35 kg/m2. Strong recommendation Non-operative management was associated with lower odds of complications (OR 2.44, 95% CI 1.47 to 4.06), although authors typically did not distinguish between minor Justification and major complications, and certainty of the evidence was very low (Supplementary Table S1). There was insufficient A meta-analysis reporting 3 RCTs was found on this topic evidence to support cost-effectiveness of operative manage- [40]. Analyses were re-performed due to error in the primary ment, however, the panel anticipated significant savings in meta-analysis (calculation of WMD instead of standardized terms of pharmacological management of comorbidities and MD, SMD). The overall quality of evidence was very low other medical and social interventions. for weight loss and low for postoperative complications due to risk of bias across RCTs, inconsistency (conceptual and statistical heterogeneity due to variety of preoperative inter- Topic 2: preoperative work‑up ventions for weight loss, and heterogeneity in the duration of follow-up) and indirectness (follow-up duration for weight Preoperative H. pylori eradication versus standard loss insufficient for generalizability of findings). Postopera- care in patients undergoing bariatric surgery tive weight loss was more pronounced in the preoperative diet consultation group (SMD 0.4, 95% CI 0.03 to 0.78 higher). No difference in the odds of postoperative com- No recommendation can be made for either routine H. pylori plications was found (risk ratio, RR, 0.80, 95% CI 0.22 to eradication or no eradication prior to bariatric surgery on the basis 2.86), although interval estimates were wide. Confidence in of available evidence. Conditional recommendation for either the intervention or the comparator the evidence was generally low (Supplementary Table S3), however the panel favored a strong recommendation after consulting with the patient representative who expressed Justification a strong preference for a holistic approach of the bariatric patient with continuous preoperative and postoperative con- There was no direct comparative observational evidence on sultation. The panel considered this practice feasible, requir- the effect of H. pylori eradication in bariatric patients. One ing moderate human and financial resources, and being meta-analysis of 4 observational studies comparing H. pylori- acceptable to stakeholders. There was no evidence of any positive- versus H. pylori-negative status was identified [37]. risk for the intervention according to the panel’s judgement. The odds for marginal ulcer (OR 0.51, 95% CI 0.03 to 8.35) and postoperative complications after bariatric surgery (OR Preoperative endoscopy versus no endoscopy 2.86, 95% CI 0.26 to 31.27) was similar for H. pylori-positive- in patients undergoing bariatric surgery? versus H. pylori-negative patients, albeit interval estimates were extremely wide and uncertainty of the evidence high. Similarly, there was no firm evidence on postoperative bleed- Esophagogastroscopy can be considered as routine diagnostic test ing (OR 0.90, 95% CI 0.23 to 3.52) or leakage (OR 1.62, prior to bariatric surgery Conditional recommendation 95% CI 0.17 to 15.62). Another meta-analysis, yielding 13 Surgical Endoscopy (2020) 34:2332–2358 2337 Table 1  Summary of recommendations Indication for bariatric Laparoscopic bariatric surgery should be considered for patients with Strong surgery BMI ≥ 40 kg/m2 and for patients with BMI ≥ 35–40 kg/m2 with associated comorbidities that are expected to improve with weight loss Laparoscopic bariatric/metabolic surgery should be considered for Strong patients with ≥ BMI 30–35 kg/m2 and type 2 diabetes and/or arte- rial hypertension with poor control despite optimal medical therapy Preoperative work-up No recommendation can be made for either routine H. pylori eradica- Conditional for either intervention or comparator tion or no eradication prior to bariatric surgery on the basis of available evidence Preoperative dietitian consultation should be considered for patients Strong undergoing bariatric surgery Esophagogastroscopy can be considered as a routine diagnostic test Conditional prior to bariatric surgery Psychological evaluation can be considered before bariatric surgery Conditional A previous diagnosis of binge eating or depression may not be con- sidered as an absolute contraindication to surgery Perioperative manage- Screening for obstructive sleep apnea using the STOP-BANG criteria Conditional ment can be considered prior to bariatric surgery Perioperative CPAP should be considered in patients with severe Strong obstructive sleep apnea syndrome who are undergoing bariatric surgery No recommendation can be made on the dose and duration of phar- Conditional for either intervention or comparator macological thromboprophylaxis in patients after bariatric surgery Inferior vena cava filter is not recommended for thromboprophylaxis Strong in patients undergoing bariatric surgery No recommendation for either an ERAS protocol or standard care Conditional for either intervention or comparator can be made on the basis of available evidence Perioperative multimodal analgesia with minimal opioid usage may Conditional be considered in patients undergoing bariatric surgery Non-bypass proce- Adjustable gastric banding surgeries are associated with a high rate Position statement dures of reoperations for complications or conversion to another bariatric procedure for insufficient weight loss in the long term Sleeve gastrectomy may be preferred over adjustable gastric banding Conditional for weight loss and control/resolution of metabolic comorbidities Sleeve gastrectomy may offer improved short-term weight loss and Position statement resolution of type 2 diabetes compared to gastric plication. No sig- nificant differences are observed at mid-term. Long-term compara- tive data on weight loss and metabolic effects are, however, lacking There is insufficient evidence to recommend routine stapler line Position statement ­reinforcementa to reduce the leak rate Staple line r­ einforcementa in sleeve gastrectomy should be consid- Strong ered to reduce the risk of perioperative c­ omplicationsb A bougie size < 36F compared to a bougie sized ≥ 36F may be rec- Conditional ommended for calibration in sleeve gastrectomy as it is associated with greater weight loss in the mid-term More extensive antral resection (2–3 cm from the pylorus ver- Position statement sus > 5 cm antral preservation) potentially offers greater weight loss in the short term without a significant increase in post-operative complications. Long term data are, however, lacking 13 2338 Surgical Endoscopy (2020) 34:2332–2358 Table 1  (continued) Bypass procedures RYGB should be preferred over adjustable gastric banding Strong RYGB results in greater weight loss and control/remission of insulin Position statement resistance and type 2 diabetes compared to gastric plication RYGB offers similar mid-term weight loss and control/remission of Position statement metabolic comorbidities compared to sleeve gastrectomy. Long- term comparative data are, however, lacking RYGB can be preferred over sleeve gastrectomy in patients with Conditional severe gastroesophageal reflux disease and/or severe esophagitis No recommendation for either BPD/DS or sleeve gastrectomy can be Conditional for either intervention or comparator made on the basis of available comparative evidence With regard to mid-term weight loss there is no difference between Position statement BPD/DS and RYGB. BPD/DS is superior to RYGB for control/ remission of type 2 diabetes. Long-term comparative data are, how- ever, lacking One anastomosis OAGB may offer greater short-term weight loss compared to RYGB, Position statement procedures gastric plication, adjustable gastric banding and sleeve gastrectomy. Long-term comparative data are, however, lacking. The effect on nutritional deficiencies remains controversial No recommendation on SADI-S compared with OAGB, BPD/DS, Conditional for either intervention or comparator RYGB or sleeve gastrectomy can be made on the basis of available evidence Revisional surgery No evidence-based criteria for indication to revisional bariatric/meta- Position statement bolic surgery are available to date The panel advises that the clinical decision to proceed to revisional bariatric/metabolic surgery be based on a complete multidiscipli- nary assessment of the patient, as recommended for the primary procedure Postoperative care Scheduled multidisciplinary post-operative follow-up should be pro- Strong vided to every patient undergoing bariatric/metabolic surgery Treatment with ursodeoxycholic acid could be considered during the Conditional weight loss phase to prevent gallstones formation Micro and/or macronutrients supplementation is recommended after Strong bariatric surgery according to the type of the procedure and to the deficiencies documented during the follow-up PPI therapy should be given to patients undergoing bypass proce- Strong dures for the prevention of marginal ulcers Postoperative nutritional and behavioral advice should be provided to Strong patients undergoing bariatric surgery Pregnancy following bariatric surgery should be delayed during the Strong weight loss phase Investigational proce- For duodenal-jejunal bypass sleeves, aspiration devices, gastric Position statement dures electrical stimulation, vagal blockade and duodenal mucosal resurfacing, the quality of evidence was too low to provide any recommendations Endoluminal suturing procedures may have a role in the treatment of Position statement patients with obesity with BMI < 40 kg/m2 Position statements do not constitute recommendations. BMI body mass index, CPAP continuous positive airway pressure, ERAS Enhanced recovery after surgery, BPD/DS biliopancreatic diversion with duodenal switch, OAGB one anastomosis gastric bypass, SADIS single-anastomo- sis duodeno-ileal switch, PPI proton-pump inhibitor a Buttress, glues, suturing, clips b Overall mortality, bleeding 13 Surgical Endoscopy (2020) 34:2332–2358 2339 Fig. 1  Evidence-based decision Bariatric surgery tree on the decision for bariatric candidate surgery or conservative man- agement. BMI body mass index. BMI values are kg/m2. Thick arrows and frames, and bold fonts indicate strong recom- mendation BMI <35 and ≥30 BMI <40 and ≥35 BMI ≥40 refractory diabetes or hypertension? comorbidies? yes no no yes conservave management Bariatric/metabolic surgery Justification Assessment of preoperative psychological conditions versus no assessment in patients Two systematic reviews were available on this topic [7, 8, undergoing bariatric surgery 41, 42] Proportion meta-analyses encompassing 23 obser- vational studies and 6845 patients suggested a summary change in surgical management after esophagogastroscopy Psychological evaluation can be considered before bariatric surgery in 7.8% (95% CI 6.1 to 9.5%). Changes of surgical man- A previous diagnosis of binge eating or depression may not be considered as an absolute contraindication to surgery agement included: hiatal hernia repairs, delays in surgery Conditional recommendation due to gastritis or peptic ulcer disease, major changes in the planned procedure and additional endoscopic dissection for suspicious lesions. Regarding a change in medical manage- Justification ment, proportion meta-analysis of 20 observational studies reporting on 5140 patients found a management change in In a meta-analysis of 26 observational studies, the preva- 27.5% (95% CI 20.2 to 34.8%) after esophagogastroscopy. lence of mental health disorders was higher among bariatric Changes of medical management included primarily H. surgery candidates compared to the general population [43]. pylori eradication and initiation of proton-pump inhibitors Furthermore, preoperative depression did not seem to be or histamine blockers for gastritis or reflux [41]. The second associated with postoperative weight loss, whereas there was meta-analysis demonstrated similar findings [42]. conflicting evidence on binge eating. Due to the inconsist- In view of the very low certainty owing primarily to risk ency of evidence, the variable availability of resources, and of bias, inconsistency, publication bias, and questionable the uncertainty of the acceptability of the intervention to value in certain circumstances, hence indirectness (Supple- stakeholders, the panel provided a conditional recommen- mentary Table S4), the panel provided a conditional recom- dation for psychological evaluation before bariatric surgery. mendation for routine esophagogastroscopy, recognizing However, the treating physician should be alert to identify that selective endoscopy in patients with upper abdominal discrete signs of psychological disorders and refer those symptoms might be more appropriate. patients for further evaluation. Similarly, due to the uncertainty of evidence and in view of the large beneficial effects of bariatric surgery on post- operative depression (Supplementary Table S5), the panel provided a conditional recommendation for bariatric surgery in the presence of a previous diagnosis of binge eating or 13 2340 Surgical Endoscopy (2020) 34:2332–2358 Preoperave work-up psychological evaluaon* no psychological evaluaon diecian available? yes no diecian consultaon endoscopy available? yes no roune gastroscopy no roune gastroscopy H. pylori? yes no eradicaon no eradicaon Bariatric/metabolic surgery Fig. 2  Evidence-based decision tree for preoperative work-up. and frames, and bold fonts indicate strong recommendation. Dotted *Psychological evaluation should be performed when psychologi- arrows and frames indicate conditional recommendation for the inter- cal disorders are suspected. Binge eating and depression might not vention. Dashed arrows and frames indicate conditional recommenda- be a contraindication for bariatric/metabolic surgery. Thick arrows tion against the intervention depression. It should be recognized, however, that different Justification interventions may have various effects on patients with dif- ferent psychological backgrounds. Current data do not allow No observational evidence directly addressing the question subgroup analyses to account for the above. Previous evi- was found. Meta-analysis of observational studies suggested dence suggests that most mental disorders (mood, anxiety, that patients with obstructive sleep apnea or related disor- bipolar disorder, eating disorders etc.) might be considered ders were more likely to sustain atrial fibrillation (OR 1.51, as a contraindication for bariatric surgery if the conditions 95% CI 1.36 to 1.69) or hypoxemia (WMD − 3.8%, 95% are severe and undertreated [44]. CI − 5.4% to − 2.2%) [45–59]. The latter outcome might not be clinically important, whereas the summary certainty in the evidence was very low due to risk of bias (non-con- Topic 3: perioperative management trolled confounders in cohort studies), imprecision, statisti- cal and conceptual heterogeneity (differences in definition Screening versus no screening for obstructive sleep of sleep apnea and method of diagnosis) (Supplementary apnea in patients prior to bariatric surgery Table 6). Nevertheless, screening using the STOP-BANG criteria seemed to be predictive of postoperative complica- tions in several observational studies [3, 4, 8, 9, 47, 48, 52, Screening for obstructive sleep apnea using the STOP-BANG crite- 53]. There was no evidence to support cost-effectiveness ria can be considered prior to bariatric surgery of diagnosis using STOP-BANG against polysomnography, Conditional recommendation however, the panel anticipated cost savings by identifying and offering intensive care to patients at risk. The panel 13 Surgical Endoscopy (2020) 34:2332–2358 2341 Fig. 3  Evidence-based decision tree for anesthetic and perio- Anesthec/perioperave perative management. CPAP management continuous positive airway pres- sure, IVCF inferior vena cava filter, ERAS enhanced recovery sleep apnea screening after surgery. *with minimal use of opioids. Thick arrows and frames, and bold fonts indicate strong recommendation. Dotted arrows and frames indicate conditional recommendation for STOP-BANG criteria polysomnography the intervention. Dashed arrows and frames indicate conditional recommendation against the intervention sleep apnea? yes no perioperave CPAP no perioperave CPAP no IVCF ERAS no ERAS mulmodal analgesia* standard care provided a conditional recommendation for using the criteria Meta-analysis of observational studies suggested higher for sleep apnea screening in candidates for bariatric surgery. odds of postoperative pneumonia (OR 0.24, 95% CI 0.07 There was agreement that, in case of clinical suspicion of to 0.82), a trend towards lower odds of reintubation (OR sleep apnea, formal screening be performed. 0.28, 95% CI 0.07 to 1.04), and shorter hospital stay (WMD − 1.6 days, 95% CI − 1.83 to − 1.28) albeit relevant evi- Perioperative continuous positive airway pressure dence was of low certainty due to imprecision and the obser- (CPAP) versus no CPAP in patients with severe sleep vational study design (Supplementary Table S7) [51, 52, 60, apnea syndrome 61]. The panel provided a strong recommendation in spite of the low certainty of the evidence, due to the severity of these complications in the bariatric patient population and Perioperative CPAP should be considered in patients with severe the low likelihood of harm associated with the intervention. obstructive sleep apnea syndrome who are undergoing bariatric surgery Strong recommendation 13 2342 Surgical Endoscopy (2020) 34:2332–2358 Fig. 4  Evidence-based deci- sion tree for the selection of Decision for bariatric surgery operative approach. BPD/ DS biliopancreatic diversion with duodenal switch, AGB adjustable gastric banding, Severe GERD symptoms and/or severe esophagis? GERD gastroesophageal reflux disease, RYGB Roux-en-Y gas- tric bypass. Thick arrows and frames, and bold fonts indicate strong recommendation. Dotted arrows and frames indicate yes no conditional recommendation for the intervention. Dashed arrows and frames indicate conditional recommendation against the sleeve sleeve intervention RYGB RYGB gastrectomy gastrectomy bougie size <36F ≥36F staple line reinforcement (any method) High‑dose versus standard‑dose pharmacological Inferior vena cava filter versus standard care antithrombotic prophylaxis after surgery for prevention of thromboembolic events after bariatric surgery No recommendation can be made on the dose and duration of phar- macological thromboprophylaxis in patients after bariatric surgery Inferior vena cava filter is not recommended for thromboprophy- Conditional recommendation for either the intervention or the laxis in patients undergoing bariatric surgery comparator Strong recommendation Meta-analysis of six observational studies suggested higher Justification risk of deep venous thrombosis (OR 2.81, 95% CI 1.33 to 5.97), similar risk of pulmonary embolism (RR 1.02, 95% Two RCTs were identified reporting on high versus standard CI 0.31 to 3.37) and a trend towards higher risk of mortal- dose low-molecular weight heparin after bariatric surgery ity with inferior vena cava filters (RR 3.27, 95% CI 0.78 to [62, 63], whereas there was no evidence on the duration of 13.64), albeit with wide interval estimates (Supplementary prophylaxis. Meta-analysis suggested no significant differ- Table S9) [64]. Due to the importance of these outcomes ence with regard to deep venous thrombosis or bleeding, and despite the low certainty of the evidence overall, this however, relevant evidence was moderate or low, due to sub- difference in effect estimates prompted the panel to provide stantial imprecision (Supplementary Table S8). The panel a strong recommendation against the use of filters outside a provided, therefore, conditional recommendation for either research protocol. high dose or standard dose prophylaxis. 13 Surgical Endoscopy (2020) 34:2332–2358 2343 evidence was very low primarily due to the observational Follow-up study design, within-study risk of bias and wide interval estimates. Statistical inconsistency was also evident, prob- muldisciplinary team available? ably reflecting conceptual heterogeneity of different ERAS protocols (Supplementary Table S10). In view of these find- ings, the panel did not favor either practice and invites fur- ther research. yes no Multimodal analgesia with minimal use of opioids follow-up by versus standard analgesia in bariatric surgery muldisciplinary team Perioperative multimodal analgesia with minimal opioid usage may be considered in patients undergoing bariatric surgery bypass procedure? Conditional recommendation yes no Justification Four observational studies and seven RCTs were identified PPI therapy reporting on multimodal postoperative analgesia in lapa- roscopic bariatric surgery [3–13, 67–76] Random-effects meta-analyses to account for conceptual heterogeneity in behavioral and analgesia protocols were performed. Most outcomes were nutrional advice addressed by few studies, hence effect estimates were not precise. Multimodal analgesia was associated with lower pregnancy desired? visual analog scale (VAS) scores and shorter stay in a post- anesthesia care unit (PACU). Of note, the odds for postop- delay pregnancy unl erative nausea and vomiting were lower with multimodal weight stabilized analgesia (OR 0.40, 95% CI 0.25 to 0.64). There was a mar- ginal benefit of multimodal analgesia with regard to post- Fig. 5  Evidence-based decision tree for postoperative follow-up. PPI operative pneumonia (RD − 0.02, 95% CI − 0.05 to 0.00). proton-pump inhibitor. Thick arrows and frames, and bold fonts indi- cate strong recommendation There was high certainty of evidence for the latter findings and very low certainty for other critical outcomes (Supple- mentary Table S11), which prompted the panel to provide a Enhanced recovery after surgery (ERAS) protocol conventional recommendation for multimodal analgesia with versus standard care for bariatric surgery minimal use of opioids. This practice may be particularly considered in patients at increased risk for opioid sensitivity and obstructive sleep apnea. No recommendation for either an ERAS protocol or standard care can be made on the basis of available evidence Conditional recommendation for either the intervention or the comparator Topic 4: operative procedures Non‑bypass procedures Justification Two meta-analyses of 11 observational and randomized studies addressed the comparative effect of ERAS versus Adjustable gastric banding standard care in bariatric surgery [1, 2, 65, 66] No differ- ences were found in major (OR 0.94, 95% CI 0.58 to 1.51) and minor postoperative complications (OR 0.88, 95% CI Position Statement 0.55 to 1.41), and mortality (RR 0.4, 95% CI 0.1 to 2.2). Adjustable gastric banding surgeries are associated with a high rate of reoperations for complications or conversion to another bariat- Hospital stay was shorter for ERAS with a mean difference ric procedure for insufficient weight loss in the long term of 2.4 days (95% CI − 3.9 to − 0.9). The certainty of the 13 2344 Surgical Endoscopy (2020) 34:2332–2358 Justification Justification Proportion meta-analysis of randomized and observational Analysis of long-term (≥ 5 years) and very long-term studies found a pooled incidence of 20% (95% CI 13% to (≥ 10 years) evidence suggested an EWL between 42 and 26%, df = 10, I2 = 89%) for complications requiring surgi- 55% with a mean weight regain between 9 and 31% for cal intervention, 2% (95% CI 1% to 3%, df = 7, I2 = 0%) for sleeve gastrectomy [9, 10, 92, 93]. Comparative long-term band erosion, 7% (95% CI 4% to 10%, df = 9, I2 = 72%) for evidence was sparse, therefore, the panel provided a posi- band removal, 4% (95% CI 3% to 5%, df = 6, I2 = 0) for port tion statement under consideration of short- and mid-term revision, and 19% (95% CI 12 to 26%, df = 8, I2 = 85%) for outcomes. Meta-analysis of summary outcomes suggests a overall complications [77–89]. WMD of 31% (95% CI 10 to 72%) in favor of sleeve gas- Four studies with a follow-up of at least 5 years were trectomy, but higher comparative odds for postoperative identified. Port-related and band-related complications were complications (OR 2.86, 95% CI 1.47 to 5.88) for the latter. documented for 18%, 23%, 27% and 43% of patients [78, 80, Certainty of the evidence across outcomes was very low, 85, 89]. Re-interventions for insufficient weight loss were primarily due to observational study design, inconsistency reported by 3 studies at follow-up > 5 years, and documented and imprecision (Supplementary Table S13). for 6%, 12% and 18% of patients [78, 80, 85]. Port revisions occurred most commonly in the first year following surgery; Technical considerations on sleeve gastrectomy: reversals and conversions were more common during years Staple line reinforcement 2 through 5. In view of this cumulative evidence, the panel provided a position statement on adjustable gastric banding. Position statement There is insufficient evidence to recommend routine stapler line Sleeve gastrectomy versus adjustable gastric reinforcement* to reduce the leak rate banding *Buttress, glues, suturing, clips, Sleeve gastrectomy may be preferred over adjustable gastric band- Recommendation ing for weight loss and control/resolution of metabolic comorbidi- Staple line reinforcement* in sleeve gastrectomy should be consid- ties ered to reduce the risk of perioperative complications** Conditional recommendation Strong recommendation *Buttress, glues, suturing, clips, **Overall mortality, bleeding Justification Justification Two network meta-analyses were available reporting on A meta-analysis of RCTs and a proportion meta-analysis weight loss and diabetes remission [90, 91]. Sleeve gastrec- addressed the topic of staple line reinforcement [94, 95]. tomy was associated with a weighted mean difference of Staple line reinforcement was associated with a 30% lower 25% EWL (95% CI 6.4% to 41%) and 57% higher odds of risk for complications overall (RR 0.7, 95% CI 0.5 to 0.9) diabetes remission (OR 0.43, 95% CI 0.19 to 0.98). The and this finding was associated with high certainty. There network for weight loss was sparse with one direct and mul- was a trend towards lower risks of bleeding (RR 0.56, 95% tiple indirect sources of evidence, which is the main reason CI 0.25 to 1.27) and leak (0.60, 95% CI 0.27 to 1.50) with- for downgrading the certainty of evidence to low (Supple- out reaching significance, however, effect estimates were mentary Table S12). Under consideration of the duration of imprecise and the certainty of evidence for these outcomes follow-up (mean, 3 years, hence indirectness) and the high downgraded (Supplementary Table S14). Under considera- incidence of band-related complications, the panel provided tion of the composite parameters, the feasibility, the cost a conditional recommendation for sleeve gastrectomy. and acceptability to stakeholders, the panel unanimously supported a strong recommendation. However, it should Sleeve gastrectomy versus gastric plication be noted that available evidence regards buttress material, glues, suturing and clips and external validity of these find- ings applies only to these interventions. Furthermore, evi- Position statement Sleeve gastrectomy may offer improved short-term weight loss and dence on the effect of buttressing material on leak was scarce resolution of type 2 diabetes compared to gastric plication. No sig- and this is reflected in the panel’s position statement. nificant differences are observed at mid-term. Long-term compara- According to the Fifth International Consensus Sum- tive data on weight-loss and metabolic effects are, however, lacking mit on Sleeve Gastrectomy, 43% of surgeons preferred 13 Surgical Endoscopy (2020) 34:2332–2358 2345 buttressing material for suture line reinforcement, 29% pre- gastroesophageal reflux (0.69, 95% CI 0.26 to 1.82). Never- ferred oversewing and the remaining 28% did not use suture theless, certainty in the evidence was very low across out- line reinforcement [96]. comes due to the observational study design, risk of bias and imprecision (Supplementary Table S16). The panel decided Technical considerations on sleeve gastrectomy: that there was insufficient evidence to form a recommenda- Bougie size tion and a position statement was provided instead. In the Fourth International Consensus Summit survey, bariatric surgeons reported that they resect the antrum at A bougie size < 36F compared to a bougie sized ≥ 36F may be rec- 4–5 cm (32%), 3–4 cm (27%), or 5–6 cm (22%) proximal to ommended for calibration in sleeve gastrectomy as it is associated the pylorus [99]. with greater weight loss in the mid-term Conditional recommendation Bypass procedures Justification Roux‑en‑Y gastric bypass (RYGB) versus adjustable A meta-analysis of observational studies comparing sleeve gastric banding gastrectomy with bougie > 36F or < 36F was identified [97]. The use of bougie of smaller caliber was associated with more pronounced weight loss (SMD 0.23, 95% CI 0.14 to RYGB should be preferred over adjustable gastric banding 0.33) and this finding was associated with moderate cer- Strong recommendation tainty. There was no difference in the odds for leak (OR 0.67, 95% CI 0.67 to 1.24), overall complications (OR 1.00, 95% Justification CI 0.73 to 1.37) or gastroesophageal reflux (OR 0.77, 97% CI 0.37 to 1.59), albeit the certainty of the evidence was very Two network meta-analyses including outcomes of pairwise low (Supplementary Table S15). The panel provided a con- comparisons addressed weight loss and diabetes remission ditional recommendation for the use of bougie sized < 36F. after RYGB and adjustable gastric banding [90, 91]. The The Fifth International Consensus Summit survey found WMD of EWL was 22% (95% CI 6.5% to 34%) in favor of that bariatric surgeons tend to use a larger bougie than previ- RYGB, which was associated with high certainty evidence. ously recorded, the median size being 36F, most probably There was no difference in diabetes remission (RR 1.96, to avoid strictures and leak associated with stricture [96]. 95% CI 0.47 to 8.33), although certainty of the evidence One of the widest differences between the consensus sum- was low (Supplementary Table S17). Nevertheless, mixed mit report of 2011 and 2014 is that more experts believe (direct and indirect) effect estimates were in favor of RYGB that smaller bougies are associated with stricture and leaks, (RR 2.65, 95% CI 1.16 to 6.07) [91]. There was no summary hence the tendency to use bougies of larger diameter (from evidence of perioperative complications, however, the panel 65% in 2011 to 79% in 2014, P = 0.006) [96]. unanimously supported a strong recommendation for RYGB over adjustable gastric banding, as it was judged that benefits Technical considerations on sleeve gastrectomy: outweigh potential risks. antral resection RYGB versus gastric plication Position Statement More extensive antral resection (2–3 cm from the pylorus ver- sus > 5 cm antral preservation) potentially offers greater weight Position Statement loss in the short term without a significant increase in post-opera- RYGB results in greater weight loss and control/remission of insu- tive complications. Long term data are, however, lacking lin resistance and type 2 diabetes compared to gastric plication Justification Justification A meta-analysis of 6 randomized and 2 observational stud- Aggregate data were available for the outcome diabetes ies addressed this topic [98]. Weight loss was more pro- remission [91]. A network meta-analysis found RYGB to nounced with antral resection (SMD 0.95, 95% CI 0.32 to be associated with higher odds for remission compared to 1.58), with no differences in staple line leak (RR 1.87, 95% gastric plication (RR 4.00, 95% CI 1.40 to 11.11), albeit CI 0.46 to 7.61), bleeding (RR 1.27, 95% CI 0.40 to 4.01) or certainty was low due to imprecision and risk of bias 13 2346 Surgical Endoscopy (2020) 34:2332–2358 (Supplementary Table S18). Mixed effect estimates were Biliopancreatic diversion with duodenal switch more precise (RR 2.86, 95% CI 1.17 to 6.98), however, still (BPD/DS) versus sleeve gastrectomy wide. The panel considered this evidence to be insufficient to form a recommendation and, in view of the scarcity of long-term data, provided a position statement instead. The No recommendation for either BPD/DS or sleeve gastrectomy can statement on weight loss is based on indirect and empirical be made on the basis of available comparative evidence Conditional recommendation for either the intervention or the evidence suggesting a durable effect of weight loss com- comparator pared to gastric plication. RYGB versus sleeve gastrectomy Justification Evidence on BPD/DS was very scarce, probably due to lim- Position Statement ited diffusion of this technique in bariatric surgeons [105]. RYGB offers similar mid-term weight loss and control/remission of Only 2 cohort studies were identified, which addressed metabolic comorbidities compared to sleeve gastrectomy. Long- term comparative data are, however, lacking morbidity and mortality [106, 107]. Effect estimates was RYGB can be preferred over sleeve gastrectomy in patients with summarized with meta-analysis, however, the certainty of severe gastroesophageal reflux disease and/or severe esophagitis evidence was very low due to imprecision (Supplementary Conditional recommendation Table S20). As such, the panel did not provide a recommen- dation for BPD/DS or sleeve gastrectomy. Justification BPD/DS versus RYGB A meta-analysis of observational studies, two meta-analyses of RCTs and two network meta-analyses addressed the com- Position Statement parative outcomes of RYGB and sleeve gastrectomy [90, With regard to mid-term weight loss there is no difference between 91, 100–102]. There was no significant difference in EWL BPD/DS and RYGB. BPD/DS is superior to RYGB for control/ (WMD − 4%, 95% CI − 14% to 8%) or diabetes remission remission of type 2 diabetes. Long-term comparative data are, (RR 0.89, 95% CI 0.73 to 1.06), findings supported by mod- however, lacking erate certainty of evidence. There was marginal difference in major operative morbidity (OR 2.04, 95% CI 1.00 to 4.16), Justification no differences in minor perioperative complications (OR 1.43, 95% CI 0.60 to 3.23), and long-term minor (OR 0.64, Four RCTs were identified and outcomes were meta-ana- 95% CI 0.28 to 1.47) or major complications (OR 0.64, 95% lyzed [27, 108–110]. Despite low risk of bias across trials, CI 0.21 to 1.96), although the latter outcomes were associ- effect estimates were imprecise and indirectness significant, ated with low or very low certainty of evidence. Remission because no long-term data were available. EWL was similar of dyslipidemia and hypertension were in favor of sleeve (WMD 14%, 95% CI − 12.21 to 42.15, very low certainty), gastrectomy, but certainty of the evidence was very low due whereas long-term morbidity (OR 3.38, 95% CI 1.14 to to observational study design, risk of bias, inconsistency and 10.05, low certainty) and diabetes remission (OR 8.06, 95% indirectness (Supplementary Table S19). CI 1.35 to 48.14) were in favor of RYGB (Supplementary Two RCTs addressed gastroesophageal reflux after RYGB Table S21). and sleeve gastrectomy [103, 104]. Remission of pre-exist- A matched cohort study on 73,702 patients from the Bar- ing gastroesophageal reflux (absolute difference − 0.36, 95% iatric Outcomes Longitudinal Database reported BPD/DS CI − 0.57 to − 0.15) and de novo gastroesophageal reflux to be associated with the greatest adjusted change in BMI was more often seen after sleeve gastrectomy (absolute dif- compared to RYGB and sleeve gastrectomy. The study also ference − 0.31%, 95% CI − 0.08% to − 0.54%) (moder- suggested that BPD/DS was superior in terms of diabetes ate and low certainty of evidence). Under consideration of remission [111]. the low certainty of evidence in important outcomes and Due to conflicting evidence and generally low certainty the lack of long-term (> 5 years) data, the panel provided a across outcomes, no recommendation was provided by the position statement on the comparative effect in the general panel. bariatric population and a conditional recommendation for patients with reflux disease. 13 Surgical Endoscopy (2020) 34:2332–2358 2347 One anastomosis procedures Single anastomosis duodeno‑ileal bypass withsleeve gastrectomy (SADI‑S) One anastomosis gastric bypass (OAGB) No recommendation on SADI-S compared with OAGB, BPD/DS, Position Statement RYGB or sleeve gastrectomy can be made on the basis of avail- OAGB may offer greater short-term weight loss compared to able evidence RYGB, gastric plication, adjustable gastric banding and sleeve Conditional recommendation for either the intervention or the gastrectomy. Long-term comparative data are, however, lacking. comparator The effect on nutritional deficiencies remains controversial Justification Justification SADI-S represents a simplified modification of the BPD/DS. OAGB is an emerging bariatric procedure which gains There was limited evidence across comparisons. increasing interest among bariatric surgeons. According to One observational study investigated the comparative the First IFSO Consensus Statement, the panel unanimously effect of SADI-S and RYGB, providing very low certainty supported that OAGB is an acceptable mainstream surgical evidence (Supplementary Table S26) [120]. Similarly, one option and 96% considered that it may no longer be regarded observational study addressed SADI-S versus BPD/DS (Sup- as new or experimental procedure [112]. plementary Table S27) and one addressed SADI-S versus As a recently developed procedure, relevant evidence was sleeve gastrectomy (Supplementary Table S28) [121, 122]. limited. Certainty of the evidence was moderate across most outcomes for the comparison OAGB versus RYGB with only 2 RCTs, which were meta-analyzed, and a network meta- Topic 5: revisional surgery analysis addressing the comparison [91, 113, 114] .Quality of life and resolution of comorbidities was similar. OAGB was associated with marginally reduced odds for in-hospital Position Statement No evidence-based criteria for indication to revisional bariatric/ morbidity (OR 0.38, 95% CI 0.13 to 1.14) and late compli- metabolic surgery are available to date cations (0.76, 95% CI 0.33 to 1.77) at the expense of less The panel advises that the clinical decision to proceed to revisional pronounced EWL (WMD 13%, 95% CI 2% to 29%; very low bariatric/metabolic surgery be based on a complete multidiscipli- certainty) (Supplementary Table S22). nary assessment of the patient, as recommended for the primary procedure A meta-analysis of four observational studies compared AGB with one anastomosis gastric bypass (OAGB) [115]. OAGB was associated with lower postoperative BMI (WMD Terminology − 7 kg/m2, 95% CI − 9 to − 4) and smaller waist circumfer- ence (WMD − 14 cm, 95% CI − 27 to − 1), whereas there The increasing use of bariatric/metabolic surgery was was no difference in diabetes remission (RR 1.48, 95% CI accompanied by a parallel increase of the number of patients 0.98 to 2.25) at a mean follow-up of 1 year (Supplementary who received an additional bariatric procedure after the Table S23). index one [123]. In 2014, the American Society for Meta- Two meta-analyses addressed the comparison OAGB bolic & Bariatric Surgery performed a systematic review on versus sleeve gastrectomy [116, 117]. As they combine ran- re-operative bariatric surgery and proposed a nomenclature domized and observational data, we meta-analyzed RCTs for dividing the secondary procedures based on the technical only to increase certainty in the evidence, when possible aspects (Supplementary Table S29) [124]. [114, 118]. EWL was more pronounced with sleeve gastrec- Reoperations after bariatric surgery may be primarily per- tomy (WMD 20%, 95% CI 20 to 23) and this finding was formed for two reasons: (a) to solve or fix complications or supported with high certainty in the evidence. The analysis side effects linked to the primary procedures; (b) to improve favored sleeve gastrectomy in terms of diabetes and dyslipi- the results in patients with insufficient weight loss, continued demia remission and there was a trend towards lower odds or poorly controlled comorbid disease, or weight regain. We for morbidity for OAGB (OR 0.67, 95% CI 0.28 to 1.61) suggest the use of the term revisional bariatric/metabolic (Supplementary Table S24). One RCT compared OAGB ver- surgery only for re-operative procedures performed for the sus gastric plication, which provided very limited evidence second group of indications. Revisional surgery can correct (Supplementary Table S25) [119]. or convert the primary procedure. The surgical procedures Under consideration of the lack of long-term data, the targeting the first category of indications are re-interven- panel provided a position statement and no recommendation. tions indicated by the patient’s medical condition, performed 13 2348 Surgical Endoscopy (2020) 34:2332–2358 electively or in emergency, and they can include conver- including endoscopic and radiological studies, with detailed sions, corrective or reversal procedures. information about the index procedure and proper evaluation Severe obesity is a chronic disease that requires lifetime of nutritional and behavioral status. treatment. While bariatric/metabolic surgery is usually an effective and durable therapy, there will be patients who respond well to the initial therapy and others with only Topic 6: postoperative care partial response, as in many other chronic diseases requir- ing medical or surgical therapy. There will be also a subset Scheduled multidisciplinary post‑operative of patients having recurrent or persistent disease. These follow‑up versus standard care patients may require escalation of therapy or a new treatment modality [124]. We, therefore, suggest that the term “failure” or “failed” in respect to metabolic/bariatric procedures be Scheduled multidisciplinary post-operative follow-up should be provided to every patient undergoing bariatric/metabolic surgery abandoned. The term “non-responders” should be adopted Strong recommendation because it is more consistent with the frame of obesity as chronic disease. Justification Clinical indications for revisional surgery A meta-analysis of summary data from five RCTs reporting We define as revisional bariatric/metabolic surgery any patients undergoing a variety of bariatric procedures and re-operative bariatric procedure performed to improve the assessing the impact of scheduled multidisciplinary post- results in patients with insufficient weight loss, continued operative follow-up versus standard care reported more pro- comorbid disease, or weight regain. However, an estab- nounced weight loss in the treatment group [128]. Sched- lished consensus on which levels of insufficient weight loss uled multidisciplinary post-operative follow-up resulted in or weight regain should be considered as indicators for the slightly greater EWL (WMD 1.6%, 95% CI 0.82% to 2.38%) need of a revisional procedure is still lacking. compared to the control group (Supplementary Table S31). Bonouvrie et al. recently performed a systematic review Despite this marginal effect and the low certainty in the evi- illustrating the lack of standard definitions of non-responders dence because of risk of bias and inconsistency, the panel after bariatric surgery [125]. This is partly due to hetero- provided a strong recommendation after consulting with the geneity among studies which precludes evidence synthesis patient representative, who expressed a strong preference for for revisional surgery. There is an urgent need to introduce close continuous preoperative and postoperative consulta- standard definitions to be used in future research and clinical tion. The panel considered this practice feasible, requiring practice. Current definitions remain arbitrary, due to the lack moderate human and financial resources, and being accept- of solid evidence in this field. A set of diagnostic criteria is able to stakeholders. There was no evidence of any risk for proposed in Supplementary Table S30, taking into consid- the intervention according to the panel’s judgement. eration current indications for bariatric/metabolic surgery and the evidence on the positive effects of a 10% weight Treatment with ursodeoxycholic acid loss [126]. during the weight loss phase following bariatric surgery Work‑up in case of revisional surgery Current evidence suggests that revisional surgery may confer Treatment with ursodeoxycholic acid could be considered during the weight loss phase to prevent gallstones formation an improvement of obesity and obesity-related comorbidities Conditional recommendation in patients without optimal results after an index procedure. Escalation of therapy in patients with poor response should be considered rational in the long-term management of a Justification chronic disease such as obesity [124]. On the other hand, revisional bariatric surgery confers a higher risk of periop- A meta-analysis of 6 RCTs and two observational studies erative complications than primary bariatric surgery [127]. found that ursodeoxycholic acid treatment versus no treat- The individual risk/benefit analysis for revisional surgery ment was associated with lower odds of gallstone formation is, therefore, even more complex than for index procedures. (OR 0.20, 95% CI 0.13 to 0.33) [129]. Due to mixed rand- We suggest that the clinical decision to proceed to revisional omized and observational study design, substantial risk of bariatric surgery be based on a complete multidisciplinary bias and publication bias, certainty in the evidence was very assessment, as recommended for the primary procedure, low (Supplementary Table S32). Under consideration of the 13 Surgical Endoscopy (2020) 34:2332–2358 2349 low-risk profile and the low cost of the intervention, the Justification panel provided a conditional recommendation, recognizing, however, that further research is warranted. Evidence supporting the need for postoperative nutritional and behavioral counseling is supported by a meta-analysis Supplementation of micro and/or micronutrients of 6 RCTs [132]. At 12-moth follow-up, the WMD of EWL after bariatric surgery was 11% (95% CI 3% to 19%) in favor of the intervention. Certainty of the evidence was, however, very low, due to risk of bias, inconsistency and indirectness because of the Micro and/or macronutrients supplementation is recommended after variety of interventions (Supplementary Table S35). Under bariatric surgery according to the type of the procedure and to the consideration of patient preferences and the anticipated fea- deficiencies documented during the follow-up Strong recommendation sibility and moderate resources, the panel supported a strong recommendation. Justification Delaying pregnancy following bariatric surgery until after the weight loss phase versus no delay Studies reporting micro and/or macronutrients supplementa- on fetal complications tion post-surgery are limited. One meta-analysis of 5 RCTs and 7 observational studies was identified, which evaluated the effect of vitamin D supplementation on preventing Vita- Pregnancy following bariatric surgery should be delayed min D deficiency [130]. Vitamin D deficiency was more during the weight loss phase common in the no supplementation group (OR 3.82, 95% Strong recommendation CI 1.70 to 8.57) (Supplementary Table S33). Despite the sparse evidence, the panel decided to provide a strong rec- Justification ommendation, as it considered that the anticipated benefits outweigh the potential risks of such practice. Six observational studies reporting fetal outcomes follow- ing pregnancy after bariatric surgery were identified and a Proton‑pump inhibitor (PPI) therapy after bariatric meta-analysis comparing early pregnancy versus delayed surgery for the prevention of marginal ulcers pregnancy was undertaken [133–138]. Delaying pregnancy was associated with a trend towards lower odds for admis- sion in the neonatal intensive care unit (OR 0.73, 95% 0.45 PPI therapy should be given to patients undergoing bypass proce- to 1.18). There were no further substantial findings, how- dures for the prevention of marginal ulcers Strong recommendation ever, certainty was very low across outcomes (Supplemen- tary Table S36). Despite this sparsity of evidence, the panel considered prudent to provide a strong recommendation for Justification delaying pregnancy during the weight loss phase to avoid fetal complications that may not have been captured by cur- A meta-analysis of three cohort studies that compared the rent studies. comparative effect of PPIs on marginal ulcers suggested beneficial effect of PPI treatment (OR 0.50, 95% CI 0.29 to 0.90, moderate certainty) (Supplementary Table S34) [131]. Topic 7: investigational procedures Under consideration of the risk/benefit ratio, the low cost and acceptability of the intervention, the panel provided a strong recommendation. Position statement For duodenal-jejunal bypass sleeves, aspiration devices, gastric Postoperative nutritional and behavioral advice electrical stimulation, vagal blockade and duodenal mucosal resurfacing, the quality of evidence was too low to provide any versus standard care recommendations Postoperative nutritional and behavioral advice should be provided to patients undergoing bariatric surgery Strong recommendation 13 2350 Surgical Endoscopy (2020) 34:2332–2358 Endoluminal suturing procedures may have a role in the treatment of the recommendations (as an aspect of external validity) of obese patients with BMI below 40 kg/m2 and to inform the topics of future updates. A total of 220 professionals involved in the management of patients with obesity responded to the 38 survey ques- Justification tions. The majority of survey participants were surgeons. Specifically, bariatric surgeons accounted for 61% of the Evidence was limited for emerging bariatric interventions total and 62% of participants worked in high volume bari- and long-term data were not available. A meta-analysis of atric centers (defined as > 50 bariatric procedures per year). four RCTs that compared EndoBarrier® with non-surgical The majority of recommendations were considered appli- management was identified [139]. EWL was 36.9% (95% CI cable to participants’ practice. Among those where applica- 29% to 45%) at 1-year follow-up (moderate certainty, Sup- bility was judged as low, was the recommendation on routine plementary Table S37). EndoBarrier® was reported to be H. pylori eradication. This may be due to the fact that pre- associated with 15.7% severe adverse events [139]. operative esophagogastroscopy is not considered standard One RCT has compared AspireAssist® with lifestyle preoperative study in many centers. Neutral recommenda- interventions and 1-year follow-up [140]. The WMD of tions were considered, as expected, to be not applicable by EWL was 22% (95% CI 14% to 30%), HbA1c improvement a substantial proportion of participants. was minimal (WMD 0.14%, 95% CI 0% to 0.28%), whereas evidence on morbidity was associated with low certainty Implications for future actions (Supplementary Table S38). No severe complications were reported. The present guidelines summarize pertinent evidence in the Three cohort studies reported on the abiliti® device and field of bariatric surgery. Despite the advances in the field, 1-year follow-up [141–143]. EWL ranged from 28.7 to we have identified several gaps, particularly in the long-term 49.3%. Few self-limiting adverse events were reported and reporting of outcomes [90, 91]. Furthermore, we have identi- 2% severe adverse events. Certainty of the evidence was, fied only two network meta-analyses, which reported several however, very low. outcomes of interest. Considering the variety of treatment Two RCTs assessing the effect of vBloc® reported 17% options, network meta-analysis is the optimal method to and 24% EWL at 1-year follow-up [144, 145]. Two-year summarize evidence across interventions in the same meta- follow-up suggested sustained weight loss [146, 147]. The analytical model and is undoubtedly a prosperous field of technical difficulty of the procedure and a high rate of severe research. adverse events are significant drawbacks to this intervention. Follow-up reports of emerging procedures, such as One cohort study reported on duodenal mucosal resurfac- OAGB, and further, large-scales RCTs on investigational ing, relevant evidence being very low [148]. Two RCTs and procedures, with robust methodology are eagerly awaited. 1 cohort study investigated the effect of the Pose® procedure As the incidence of obesity increases in societies with a and reported EWL between 16–45% [149–151]. The proce- high prevalence of psychological disorders, further investi- dure safety profile seems acceptable, however certainty in gation on the indications for bariatric surgery is warranted. the evidence was very low. Furthermore, obesity is an emerging problem in developing Five observational studies have addressed the use of countries and, as such, healthcare authorities are called to OverStitch™ [152–156]. The procedure may be considered promote health equity by ensuring access to healthcare for safe, well tolerated and effective with a mean EWL of 50% underprivileged and vulnerable populations. at 1 year. Evidence suggests durability of plications and pro- gressive weight loss up to 2 years. Conclusions Comments Evidence from clinical research suggests that bariatric sur- gery is highly effective in the management of obesity. This Survey results document summarizes the latest evidence on bariatric sur- gery. It was developed in compliance with state-of-the art The guideline development group aimed to investigate methodological principles to reliably appraise evidence, whether recommendations and position statements are appli- hereby facilitating evidence-based clinical decisions and cable and can be transferred to individuals’ clinical practice. informing authoritative actions of policymakers and other Indeed, one of the AGREE II domains is focused on the stakeholders. applicability of the guideline in the practice of target users. The rationale was therefore both to assess the clinical merit 13 Surgical Endoscopy (2020) 34:2332–2358 2351 Acknowledgements We would like to thank Prof. Lilian Kow, Presi- final approval of the version to be published, agreement to be account- dent of IFSO and Director of the Adelaide Bariatric Centre; and Prof. able for all aspects of the work. DG: Interpretation of data, critical revi- Scott Shikora, Director of the Center for Metabolic and Bariatric Sur- sion for important intellectual content, final approval of the version to gery at Brigham and Women’s Hospital and Professor of Surgery at be published, agreement to be accountable for all aspects of the work. Harvard Medical School, President Elect of IFSO for their external JCGH: Interpretation of data, critical revision for important intellectual review of these guidelines. The input of Mr. Carlos Oliveira as patient content, final approval of the version to be published, agreement to be representative is greatly appreciated. We would like to extend our spe- accountable for all aspects of the work 4 Jitka Herlesova: Acquisition cial thanks to Zbigniew Leś for kindly providing a trial version of and analysis of data, drafting the work, final approval of the version to GRADEpro for enterprises, including PanelVoice 2.0. be published, agreement to be accountable for all aspects of the work. MK: Acquisition, analysis and interpretation of data, critical revision Author contributions I confirm that authors of the manuscript SEND- for important intellectual content, final approval of the version to be D-20-00157 fulfill the ICMJE authorship criteria (http://www.icmje. published, agreement to be accountable for all aspects of the work. org/recommendations/browse/roles-and-responsibilities/defining-the- HK: Acquisition of data, critical revision for important intellectual role-of-authors-and-contributors.html) and have contributed to the sub- content, final approval of the version to be published, agreement to be mitted work as follows: NDL: Conception and design, interpretation of accountable for all aspects of the work. SM-C: Interpretation of data, data, drafting the work, final approval of the version to be published, critical revision for important intellectual content, final approval of the agreement to be accountable for all aspects of the work. SAA: Concep- version to be published, agreement to be accountable for all aspects of tion and design, analysis and interpretation of data, drafting the work, the work. GP: Acquisition and analysis of data, drafting the work, final final approval of the version to be published, agreement to be account- approval of the version to be published, agreement to be accountable able for all aspects of the work. RLB: Interpretation of data, critical for all aspects of the work. GP: Interpretation of data, critical revision revision for important intellectual content, final approval of the version for important intellectual content, final approval of the version to be to be published, agreement to be accountable for all aspects of the published, agreement to be accountable for all aspects of the work. SP: work. LB: Interpretation of data, critical revision for important intel- Acquisition and analysis of data, drafting the work, final approval of lectual content, final approval of the version to be published, agreement the version to be published, agreement to be accountable for all aspects to be accountable for all aspects of the work. DG: Acquisition, analysis of the work. AP: Acquisition and analysis of data, drafting the work, and interpretation of data, critical revision for important intellectual final approval of the version to be published, agreement to be account- content, final approval of the version to be published, agreement to be able for all aspects of the work. SR: Acquisition and analysis of data, accountable for all aspects of the work. AI: Acquisition and analysis drafting the work, final approval of the version to be published, agree- of data, drafting the work, final approval of the version to be pub- ment to be accountable for all aspects of the work 5. ER: Acquisition lished, agreement to be accountable for all aspects of the work 2. FMC: and analysis of data, drafting the work, final approval of the version Acquisition and analysis of data, drafting the work, final approval of to be published, agreement to be accountable for all aspects of the the version to be published, agreement to be accountable for all aspects work. SS-C: Acquisition and analysis of data, drafting the work, final of the work. FA: Interpretation of data, critical revision for important approval of the version to be published, agreement to be accountable intellectual content, final approval of the version to be published, agree- for all aspects of the work. RV: Interpretation of data, critical revision ment to be accountable for all aspects of the work. IA: Acquisition and for important intellectual content, final approval of the version to be analysis of data, drafting the work, final approval of the version to be published, agreement to be accountable for all aspects of the work. GS: published, agreement to be accountable for all aspects of the work. CA: Conception and design, interpretation of data, drafting the work, final Acquisition and analysis of data, drafting the work, final approval of approval of the version to be published, agreement to be accountable the version to be published, agreement to be accountable for all aspects for all aspects of the work. of the work. NB: Interpretation of data, critical revision for important intellectual content, final approval of the version to be published, agree- Funding This work was funded by the European Association for Endo- ment to be accountable for all aspects of the work. MCBP: Interpreta- scopic Surgery (EAES). The funding body did not have any influence tion of data, critical revision for important intellectual content, final on the content of this work. approval of the version to be published, agreement to be accountable for all aspects of the work. MB: Acquisition and analysis of data, draft- ing the work, final approval of the version to be published, agreement Compliance with ethical standards to be accountable for all aspects of the work. CC: Interpretation of data, critical revision for important intellectual content, final approval of the Disclosures Rachel L. Batterham reports other from Novo Nordisk, version to be published, agreement to be accountable for all aspects of personal fees from Novo Nordisk, other from Pfizer, personal fees from the work. MDL: Interpretation of data, critical revision for important Nestlé, personal fees from International Medical Press, outside the sub- intellectual content, final approval of the version to be published, agree- mitted work. Luca Busetto reports personal fees from Novo Nordisk, ment to be accountable for all aspects of the work 3. DD: Interpreta- personal fees from Bruno Farmaceutici, grants from Enzymmanage- tion of data, critical revision for important intellectual content, final ment, outside the submitted work. Salvador Morales-Conde reports approval of the version to be published, agreement to be accountable personal fees from BD Bard, grants and personal fees from Medtronic, for all aspects of the work. ADV: Acquisition and analysis of data, personal fees from Ethicon, personal fees from Olympus, personal fees drafting the work, final approval of the version to be published, agree- from Stryker, personal fees from BBraum, personal fees from Dipro, ment to be accountable for all aspects of the work. DMF: Acquisition personal fees from Baxter, personal fees from Gore, outside the submit- and analysis of data, drafting the work, final approval of the version to ted work. Nicola Di Lorenzo, Stavros A. Antoniou, Daniela Godoroja, be published, agreement to be accountable for all aspects of the work. Angelo Iossa, Francesco M. Carrano, Ferdinando Agresta, Isaias Alar- NKF: Interpretation of data, critical revision for important intellectual çon, Carmil Azran, Nicole Bouvy, M. Carmen Balaguè Ponz, Maura content, final approval of the version to be published, agreement to Buza, Catalin Copaescu, Maurizio De Luca, Dror Dicker, Angelo Di be accountable for all aspects of the work. MF: Interpretation of data, Vincenzo, Daniel M. Felsenreich, Nader K. Francis, Martin Fried, critical revision for important intellectual content, final approval of the Berta Gonzalo Prats, David Goitein, Jason C.G. Halford, Jitka Herles- version to be published, agreement to be accountable for all aspects ova, Marina Kalogridaki, Hans Ket, Giacomo Piatto, Gerhard Prager, of the work. BGP: Acquisition and analysis of data, drafting the work, Suzanne Pruijssers, Andrea Pucci, Shlomi Rayman, Eugenia Romano, 13 2352 Surgical Endoscopy (2020) 34:2332–2358 Sergi Sanchez-Cordero, Ramon Vilallonga, and Gianfranco Silecchia provide a link to the Creative Commons licence, and indicate if changes have nothing to disclose. were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in Open Access This article is licensed under a Creative Commons Attri- the article’s Creative Commons licence and your intended use is not bution 4.0 International License, which permits use, sharing, adapta- permitted by statutory regulation or exceeds the permitted use, you will tion, distribution and reproduction in any medium or format, as long need to obtain permission directly from the copyright holder. To view a as you give appropriate credit to the original author(s) and the source, copy of this licence, visit http://creat​iveco​mmons​.org/licen​ses/by/4.0/. Appendix Content Coordinators Nicola Di Lorenzo & Gianfranco Silecchia EAES Methodological Coordinator EASO Paent Task Force Stavros A. Antoniou – EAES Research Commiee & Guideline Subcommiee Carlos Oliveira Scienfic Commiee Clinical librarian Nader Francis & Ferdinando Agresta – EAES Research Commiee Hans Ket Angelo Iossa & Francesco M. Carrano – EAES junior coordinators Guideline Panel Rachel Baerham (IFSO-EC), Luca Buseo (EASO), Nicole Bouvy (EAES), Catalin Copaescu (EAES), Maurizio De Luca (IFSO-EC), Dror Dicker (EASO), Daniela Godoroja (ESPCOP), Marn Fried (IFSO-EC), David Goitein (EAES), Jason Halford (EASO), Marina Kalogridaki (EAES), Salvador Morales Conde (EAES), Gerhard Prager (IFSO-EC), Carmen B. Pónz (EAES), Ramon Villalonga (EAES) Junior Parcipants Isaias Alarçon, Carmil Azran, Maura Buza, Angelo Di Vincenzo, Daniel Moritz Felsenreich, Berta Gonzalo Prats, Jitka Herlesova, Giacomo Piao, Suzanne Pruijssers, Andrea Pucci, Shlaomi Rayman, Eugenia Romano, Sergi Sanchez-Cordero 13 Surgical Endoscopy (2020) 34:2332–2358 2353 References 20. GRADE Working Group (2015) GRADEpro guideline develop- ment tool [software]. McMaster Univ 21. O’Brien PE, Dixon JB, Laurie C et al (2006) Treatment of mild 1. Qasim A, Turcotte M, de Souza RJ et al (2018) On the origin of to moderate obesity with laparoscopic adjustable gastric banding obesity: identifying the biological, environmental and cultural or an intensive medical program. Ann Intern Med 144(9):625. drivers of genetic risk among human populations. Obes Rev. https​://doi.org/10.7326/0003-4819-144-9-20060​5020-00005​ https​://doi.org/10.1111/obr.12625​ 22. Dixon JB, O’Brien PE, Playfair J et al (2008) Adjustable gastric 2. 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Horbach T, Thalheimer A, Seyfried F, Eschenbacher F, Schuh- mann P, Meyer G (2015) a­ biliti® closed-loop gastric electrical Publisher’s Note Springer Nature remains neutral with regard to stimulation system for treatment of obesity: clinical results with jurisdictional claims in published maps and institutional affiliations. a 27-month follow-up. Obes Surg. https​://doi.org/10.1007/s1169​ 5-015-1620-z 13 2358 Surgical Endoscopy (2020) 34:2332–2358 Affiliations Nicola Di Lorenzo1 · Stavros A. Antoniou2,3 · Rachel L. Batterham4,5 · Luca Busetto6 · Daniela Godoroja7 · Angelo Iossa8 · Francesco M. Carrano9 · Ferdinando Agresta10 · Isaias Alarçon11 · Carmil Azran12 · Nicole Bouvy13 · Carmen Balaguè Ponz14 · Maura Buza15 · Catalin Copaescu15 · Maurizio De Luca16 · Dror Dicker17 · Angelo Di Vincenzo6 · Daniel M. Felsenreich18 · Nader K. Francis19 · Martin Fried20 · Berta Gonzalo Prats14 · David Goitein21,22 · Jason C. G. Halford23 · Jitka Herlesova20 · Marina Kalogridaki24 · Hans Ket25 · Salvador Morales‑Conde11 · Giacomo Piatto16 · Gerhard Prager18 · Suzanne Pruijssers13 · Andrea Pucci4,5 · Shlomi Rayman21,22 · Eugenia Romano23 · Sergi Sanchez‑Cordero26 · Ramon Vilallonga27 · Gianfranco Silecchia8 14 * Gianfranco Silecchia Hospital Sant Pau, UAB, Barcelona, Spain gianfranco.silecchia@uniroma1.it 15 Department of General Surgery, Ponderas Academic Hospital 1 Regina Maria, Bucharest, Romania Department of Surgical Sciences, University of Rome “Tor 16 Vergata”, Rome, Italy Division of General Surgery, Castelfranco and Montebelluna 2 Hospitals, Treviso, Italy Department of Surgery, European University of Cyprus, 17 Nicosia, Cyprus Department of Internal Medicine D, Hasharon Hospital, 3 Rabin Medical Center, Sackler School of Medicine, Tel Aviv Department of Surgery, Mediterranean Hospital of Cyprus, University, Tel Aviv, Israel Limassol, Cyprus 18 4 Division of General Surgery, Department of Surgery, Vienna Centre for Obesity Research, University College London, Medical University, Vienna, Austria London, UK 19 5 Department of General Surgery, Yeovil District Hospital Biomedical Research Centre, National Institute of Health NHS Foundation Trust, Yeovil, UK Research, London, UK 20 6 Center for Treatment of Obesity and Metabolic Disorders, Internal Medicine 3, Department of Medicine, DIMED, OB Klinika, Prague, Czech Republic Center for the Study and the Integrated Treatment of Obesity, 21 University Hospital of Padua, Padua, Italy Sackler School of Medicine, Tel Aviv University, Tel Aviv, 7 Israel Department of Anesthesiology, Ponderas Academic Hospital 22 Regina Maria, Bucharest, Romania Department of Surgery C, Chaim Sheba Medical Center, 8 Ramat Gan, Israel Department of Medical‑Surgical Sciences 23 and Biotechnologies, Faculty of Pharmacy and Medicine, Department of Psychological Sciences, Institute “La Sapienza” University of Rome-Polo Pontino, Bariatric of Psychology, Health and Society, University of Liverpool, Centre of Excellence IFSO-EC, Via F. Faggiana 1668, Liverpool, UK 04100 Latina, Italy 24 Emergency Department, General Hospital of Attica “KAT”, 9 Department of Endocrine and Metabolic Surgery, University Athens, Greece of Insubria, Ospedale di Circolo and Fondazione Macchi, 25 VU Amsterdam, Amsterdam, Netherlands ASST Sette Laghi, Varese, Italy 26 10 General Surgery Department, Consorci Sanitari de L’Anoia, Department of General Surgery, ULSS5 del Veneto, Adria, Barcelona, Spain Italy 27 11 Endocrine, Metabolic and Bariatric Unit, General Surgery Unit of Innovation in Minimally Invasive Surgery, Department, Vall D’Hebron University Hospital, Center Department of General and Digestive Surgery, University of Excellence for the EAC‑BC, Universitat Autònoma de Hospital “Virgen del Rocío”, 41010 Sevilla, Spain Barcelona, Barcelona, Spain 12 Herzliya Medical Center, Herzliya, Israel 13 Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands 13