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IFSO Consensus on definitions and clinical practice guidelines (part 4)

Updated: Sep 6, 2023

In part four of our report from Hamburg, topics under discussion included revision surgery, VTE prophylaxis, surgery for class 1 obesity, Preoperative weight loss for the metabolically challenged patient and more. The following are the brief highlights from the presentations.

Conversion or revision surgery after sleeve gastrectomy

Dr Estuardo Behrens (New Life Center, Guatemala) began his presentation by stating that all of the evidence in his presentation has a grade of evidence of 1 and 2. He said that following SG, GERD symptoms increase by 19%-31.8% and GERD appears de novo in 23%-31.6% (Yeung, et al. Does Sleeve Gastrectomy Expose the Distal Esophagus to Severe Reflux?: A Systematic Review and Metaanalysis. Annals of surgery, 271(2), 257–265, and Sharples et al. Systematic Review and Meta-Analysis of Randomised Controlled Trials Comparing Long-Term Outcomes of Roux-En-Y Gastric Bypass and Sleeve Gastrectomy. Obesity surgery, 30(2), 664–672, level 1). The paper by Sharples et al also showed following SG, there was GERD remission in 25% of patients.


He added that following SG, Barrett’s esophagus is seen in 8 to 11% (Yeung, et al and Qumseya et al. Barrett’s esophagus after sleeve gastrectomy: a systematic review and meta-analysis. Gastrointestinal endoscopy, 93(2), 343–352.e2, level 1) and 3.1% to 4% of patients will need revisional surgery for GERD (Yeung, et al and Guan et al. Mid-long-term Revisional Surgery After Sleeve Gastrectomy: a Systematic Review and Meta-analysis. Obesity surgery, 29(6), 1965–1975, level 1).


Thirty percent of cases of revisional surgery after SG are due to GERD and GERD is resolved in 79% of cases after conversion from SG to RYGB (Matar et al. Indications and Outcomes of Conversion of Sleeve Gastrectomy to Roux-en-Y Gastric Bypass: a Systematic Review and a Meta-analysis. Obesity surgery, 31(9), 3936–3946, level 1).


The frequency of SG was 61% in 2020 of bariatric surgeries performed in the US and Canada (The ASMBS total bariatric procedure numbers are based on the best estimation from available data (BOLD,ACS/MBSAQIP, National Inpatient Sample Data and outpatient estimations, level 1) and the incidence of leaks varies from 0.75 (Al-Kurd et al. Not all leaks are created equal: a comparison between leaks after sleeve gastrectomy and Roux-En-Y gastric bypass. Obes Surg. 2018;28(12):3775–82) to 7% (Kim et al. ASMBS position statement on prevention, detection, and treatment of gastrointestinal leak after gastric bypass and sleeve gastrectomy, including the roles of imaging, surgical exploration, and nonoperative management. Surg. Obes. 11 (2015) 739–748) and 0.74 – 1.7% (Benedix et al. Staple Line Leak After Primary Sleeve Gastrectomy – Risk Factors and Mid–term Results: Do Patients Sill Benefit from the Weight Loss Procedure? All Level 1). He added that leaks are the second leading cause of death after MBS with a mortality rate of 0-1.4% (Gagner M, Hutchinson C, Rosenthal R. Fifth International Consensus Conference: current status of sleeve gastrectomy. Surg Obes Relat Dis. 2016;12(4):750–6, level 3).


Leaks typically present and are diagnosed three weeks after surgery in 88.9% of cases and in 94% of cases is located on the upper 1/3 of the staple line (Cesana et al Proximal leakage after laparoscopic sleeve gastrectomy: an analysis of preoperative and operative predictors on 1738 consecutive procedures. Obes Surg. 2018;28(3):627–35), primarily associated with mechanic and ischemic factors.

A study by Guan et al. (Mid-longterm Revisional Surgery After Sleeve Gastrectomy: a Systematic Review and Meta-analysis. Obesity surgery, 29(6), 1965–1975) reported revisional surgery after SG has increased up to 30%, particularly because SG allows any procedure as a second chance. However, Matar et al) Indications and Outcomes of Conversion of Sleeve Gastrectomy to Roux-en-Y Gastric Bypass: a Systematic Review and a Metaanalysis. Obesity surgery, 31(9), 3936–3946, level 1) found that revisional surgery because of RWG or suboptimal response after SG is up to 52%. He added that the role of the multidisciplinary team is crucial and enhancing adherence to postoperative dietary protocols and regular follow-up monitoring sessions is necessary to optimise weight outcomes (Pinto-Bastos et al. Reoperative Bariatric Surgery: a Systematic Review of the Reasons for Surgery, Medical and Weight Loss Outcomes, Relevant Behavioral Factors. Obesity surgery, 27(10), 2707–2715, level 1).


He ended his presentation by outlining the factors associated with RWG and Cesana et al. (Proximal leakage after laparoscopic sleeve gastrectomy: an analysis of preoperative and operative predictors on 1738 consecutive procedures. Obes Surg. 2018;28(3):627–35, level 1) found that an increased gastric volume is one of the factors of RWG, although hormonal changes have not been demonstrated in patients with RWG. In addition, dietary risk factors include increased sweet consumption and portion size, emotional eating and loss of control and disinhibition when eating, and there is evidence that patients with RWG had lower physical activity, compared with those with no weight regain. Finally, Cesana et al. reported that the only psychiatric risk factor that has been consistently shown to be associated with RWG was anxiety.

MBS in Class I obesity

Dr Ali Aminian (Cleveland Clinic, Cleveland, USA). There are three groups in which MBS can be considered for patients living with Class I Obesity: patients with T2DM, patients with other medical conditions associated with obesity (no T2DM) and those patients with no apparent comorbidities.

In December 2022, the American Diabetes Association published the ADA Standard of Care in Diabetes 2023 (El Sayed et al. Obesity and Weight Management for the Prevention and Treatment of Type 2 Diabetes: Standards of Care in Diabetes—2023. Diabetes Care 1 January 2023; 46 (Supplement_1): S128–S139) recommended that: “Metabolic surgery may be considered as an option to treat type 2 diabetes in adults with BMI 30.0–34.9 kg/m2 (27.5–32.4 kg/m2 in Asian American individuals) who do not achieve durable weight loss and improvement in comorbidities (including hyperglycaemia) with nonsurgical methods.


In addition, the ASMBS/IFSO 2022 Guidelines (Eisenberg et al. American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO): Indications for Metabolic and Bariatric Surgery. Surg Obes Relat Dis. 2022 Dec;18(12):1345-1356) stated: Metabolic surgery is recommended in patients with T2D and BMI≥30 kg/ m2 . The guidelines also recommended that BMI thresholds should be adjusted in the Asian population such that a BMI ≥25 kg/m2 suggests clinical obesity, and individuals with BMI ≥27.5 kg/m2 should be offered metabolic and bariatric surgery.


Aminian said there are several observational studies demonstrating the safety and efficacy of MBS in patients with Class I Obesity with comorbidities other than T2DM, resulting in improvements in hypertension, dyslipidaemia, obstructive sleep apnoea, asthma, joint pain, quality of life, etc. This evidence resulted in an additional statement: MBS should be considered in individuals with BMI of 30–34.9 kg/m2 who do not achieve substantial or durable weight loss or comorbidity improvement using nonsurgical methods.


For those patients with no apparent comorbidities, he said there is limited data on outcomes of MBS. This is despite Class I obesity (BMI 30-35) being a well-defined disease, increasing the risk of other diseases (cardiovascular disease cancer etc), as well as impact a person’s quality of life.


“A BMI of 35 is an arbitrarily and non-scientific cut point and the current options of nonsurgical treatment are generally ineffective,” he said. “Class I obesity patients there is no risk of excessive weight loss as with an average 5-6 points drop in BMI, a person’s weight usually stabilises around BMI 25 kg/m2 . The surgical risk in Class I obesity patients is consistent with what has been reported for patients with severe obesity.”


VTE prophylaxis in MBS

Next, Dr Ashraf Haddad (Jordan Hospital, Amman, Jordan) discussed the role of venous thromboembolism (VTE) prophylaxis in MBS. He said that there was poor level of evidence (two review articles, five systematic reviews and meta-analysis), making any recommendation Grade B at best.


All MBS patients are a moderate risk, at least, for VTE. Therefore, pharmacological prophylaxis is low risk and potentially of benefit and should be used in all cases. However, the use of mechanical prophylaxis alone is associated with higher VTE rate than mechanical combined with pharmacological prophylaxis. Low molecular weight heparin (LMWH) is the most commonly used pharmacologic agent, results in the lowest VTE rate and is more effective than Unfractionated Heparin (UFH), although the literature shows that the bleeding rate is the same. LMWH and Fondaparinux (factor Xa inhibitor) may be equally effective in reducing VTE.

Regarding augmented dose and extended prophylaxis, Haddad said there is no difference if prophylaxis is started before or after a procedure and there is no data on extended prophylaxis in terms of VTE or major bleeding (very low quality and inconclusive evidence). In addition, there is little or no evidence on augmented doses in terms of VTE or major bleeding. However, low level evidence suggested that dose adjusted regimens seem to be associated with lower VTE (not statistically significant).


Finally, he discussed the use of IVC Filters, which he said were associated with higher complication rates and there is insufficient evidence that they reduce the rates of pulmonary embolism. Indeed, they result in a significantly higher risk of DVT (RR 2.81) and slightly increase mortality. Therefore, he concluded that there is no evidence supporting the use of IVC filters in MBS.


Preoperative weight loss for the metabolically challenged patient (BMI>50 kg/m2 )?

In his presentation, Professor Scott Shikora (Brigham and Women’s Hospital – President, IFSO) asked whether there is a benefit to preoperative weight loss for the metabolically challenged patient (BMI>50 kg/m2 )? Although preoperative weight loss offers potential medical, surgical and behavioural benefits, it is controversial, particularly for the metabolically challenged patient (BMI>50 kg/m2 ). He explained that there are both supportive and non-supportive published articles and if it is necessary, how much weight loss is required and in what instance – selectively or mandatory for all patients?


The potential medical benefits include improved blood glucose control and sleep apnea, diuresis of excessive fluid resulting in decreased blood volume and improved left ventricular function, improved proinflammatory and prothrombotic states, and improved functional reserve capacity and lung volumes. In a prospective cohort study of 51 patients with IDDM undergoing MBS, Biro et al (J Surg Res. 2013;185:1-5), placed patients on an LCD two weeks prior to surgery. Those patients who achieved >50% reduction in total insulin requirements on the LCD experienced a higher rate of early diabetes remission (44% vs 13.6 % at 6 months (p<0.01) and 72.7%vs 5.9% at 12 months (p<0.01)). In addition, they had greater weight loss vs non-responders.


A RCT by Solomon et al. (JACS, 2009;208:241-245) that compared patients who lost 10% body weight preoperatively with patients with no weight loss, reported patients in the weight loss group lost 8.2% of their excess weight while patients in the control group gained 1.1% (p=0.007). They also demonstrated better weight loss at one-year post-op. Benotti et al (Comment on: Preoperative weight loss: a value-added opportunity. Surg Obes Relat Dis, 2021;17:1853-1854. Editorial) noted that even modest weight loss may improve glycaemic control, reduce the frequency and severity of sleep apnoea events, improve gas exchange, lower blood pressure, reduce risk of thromboembolism, lower pulmonary artery pressures, reduce systemic inflammation and diminish liver size.


In a systematic review of 15 articles (n=3404 patients) to see if preoperative weight loss immediately prior to MBS improved outcomes, Livhits et al. (Does weight loss immediately before bariatric surgery improve outcomes: a systematic review. 2009;6:713-21) reported five found a positive effect of preoperative weight loss on postoperative weight loss, two found a positive short-term effect that was not sustained long term, five did not find an effect difference, and one found a negative effect.


A meta-analysis revealed a significant increase in the one-year postoperative weight loss (mean difference of 5% EWL, 95% confidence interval 2.68–7.32) for patients who had lost weight preoperatively. A meta-analysis of other outcomes revealed a decreased operative time for patients who had lost weight preoperatively (mean difference 23.3 minutes, 95% confidence interval 13.8–32.8). However, Carlin et al. (Preoperative weight loss is not a predictor of postoperative weight loss after Rouxen-Y gastric bypass. Surg Obes Relat Dis 2008;4:481-485), conclude there was no correlation between the %EWL and percentage of preoperative weight loss. The potential surgical benefits include a reduction of abdominal wall thickness allowing for more freedom of movement of the trocars and instruments, a reduction of visceral fat improved visualisation of the viscera, a reduction of liver size improved working space and visibility, safer liver retraction, improved pneumoperitoneum, reduced OR time and perioperative complications, and improved postoperative weight loss.


A systematic review by Ochner et al. (Pre-bariatric surgery weight loss requirements and the effect of preoperative weight loss on the postoperative outcome, Int J Obes, 2012;36, 1380-7), concluded that preoperative requirements are ineffective in fostering preoperative weight loss and preoperative weight loss may lead to improvements in at least some relevant postoperative outcomes. However, the limited number and quality of prospective studies in this area prohibit the establishment of standards of practice for pre-bariatric requirements.


A RCT by Alami et al. (Is there a benefit to preoperative weight loss in gastric bypass patients? A prospective randomized trial. Surg Obes Relat Dis 2007; 3: 141–145), reported preop weight loss group lost more weight at 3 months postop, but no difference at 6 months. However, univariate analysis by Benotti et al. (Preoperative weight loss before bariatric surgery. Arch Surg 2009,;144:1150-1155) revealed that increasing preoperative weight loss is associated with reduced complications. Increased preoperative weight loss was a predictor of reduced complications.


A systematic analysis by Bettini et al. (Diet approach before and after bariatric surgery. Rev Endocr Metab Disord, 2020;21:297-306) found the results were inconsistent – and randomised and retrospective studies also did not support the hypothesis that pre-operative weight loss could improve weight loss after bariatric surgery. Modest preoperative weight loss, however, may facilitate surgery and reduce complications. A systematic review by Holderbaum et al. (Effects of very low, calorie diets on liver size and weight loss in the preoperative. period of bariatric surgery: a systematic review. Surg Obes Relat Dis 2018, 14:237-244) reported weight loss of 2.8-14.8 kg and liver size reduced of 5%- 20%. Despite the weight loss, there was no reduction in perioperative complications.


Finally, a RCT by Gils et al. (Effects of preparatory weight loss diets on hepatic volume, metabolic parameters, and surgical complications in morbidly obese bariatric surgery candidates: a randomized clinical trial. Obes Surg 2018;28:37-56-3768) compared VLCD and LCD in pre-bariatric surgery patients. Despite significant reductions in hepatic volume but similar in both groups and total weight loss of 5.8 % for the VLCD and 4.2% for the LCD (p=0.004), both groups had similar reductions in serum lipids and glomerular filtrations rates. Most markers were not significantly lowered.

The potential behavioural benefits include better postoperative weight loss, the patient demonstrating the ability to follow instructions and the ability to adhere to a post-bariatric surgery follow-up program, the ability to assess a patient’s motivation and willingness to stay on the post-bariatric surgery diet and improve a patient’s confidence that they can successfully lose weight.

“Preoperative weight loss can result in multiple physiological, surgical and behavioural benefits. However, whether these improvements result in improved surgical outcomes remains controversial as the current published literature is inconclusive,” Shikora concluded. “Therefore, preoperative weight loss should be selectively used at the discretion of the Multidisciplinary Team and not mandatory for all surgical candidates.”

Metabolically challenged/high BMI patient – sleeve gastrectomy or hypo-absorptive procedure?

Professor Luigi Angrisani (“Federico II” University, Naples, Italy) asked whether a metabolically challenged patient/High BMI should have a sleeve gastrectomy or a hypo-absorptive procedure. He believes that in a metabolically-challenged patient, a two-step approach (e.g., sleeve gastrectomy + second procedure) should be considered and papers by Ren et al. (Obes Surg. 2000 Dec;10(6):514-23), Regan et al (Early experience with two-stage laparoscopic Roux-en-Y gastric bypass as an alternative in the super-super obese patient. Obes Surg. 2003 Dec;13(6):861-4) and Dapri et al (Superobese and supersuperobese patients: 2-step laparoscopic duodenal switch. Surg Obes Relat Dis. 2011 Nov-Dec;7(6):703-8) all concluded that a two-stage approach (BPD-DS, sleeve gastrectomy with second-stage Roux-en-Y gastric and 2-step LBPD/DS) are effective for both weight loss and resolution of co-morbidities.


However, he noted that there is no consensus concerning the best MBS procedure for individuals with especially high BMI, but the efficacy and safety of MBS have been clearly demonstrated in this population. This was shown in a paper by Soong et al. (Long-Term Efficacy of Bariatric Surgery for the Treatment of Super-Obesity: Comparison of SG, RYGB, and OAGB. Obes Surg. 2021 Aug;31(8):3391- 3399) that compared SG, RYGB and OAGB in patients with severe obesity. They reported that SG is an effective and durable primary bariatric procedure for the treatment of super obesity and metabolic disorders, RYGB had a higher 30-day postoperative major complication rate (4.8%) than SG (0.5%) and OAGB (0.8%), and SG had a lower remission rate in dyslipidaemia comparing to OAGB and RYGB, but T2DM remission rate was no different between the groups.


Furthermore, a single-stage RYGB can be performed safely for patients with BMI 60, as reported by Abeles et al (Primary laparoscopic gastric bypass can be performed safely in patients with BMI>or= 60. J Am Coll Surg. 2009 Feb;208(2):236- 40), who found there were no differences in the incidence of complications or mortality for patients with a BMI>or= 60 undergoing LGBP compared with those with a BMI<60. Interestingly, they said that the greater experience and skill of the attending surgeons versus those of a chief resident or fellow in training probably resulted in fewer intraoperative adverse events. Regarding hiatal hernias, he said in a metabolically-challenged patient, hiatal hernias (HH) should be repaired independent of the type of approach (1 or 2 steps) or type of operation.


A study by Lewis et al. (Concurrent hiatal hernia repair and bariatric surgery: outcomes after sleeve gastrectomy and Roux-en-Y gastric bypass. Surg Obes Relat Dis. 2021 Jan;17(1):72-80) that matched 1,546 SG patients with HHR to 3,170 SG patients without HHR, and 457 RYGB patients with HHR to 1,156 RYGB patients without HHR. Patients who underwent concurrent SG and HHR were more likely to have additional abdominal operations (adjusted hazard ratio [aHR], 2.1; 95% CI, 1.5–3.1) and endoscopies (aHR, 1.5; 95% CI, 1.2–1.8) but not bariatric revisions/ conversions (aHR, 1.7; 95% CI, .6–4.6) by 1 year after surgery, maintained at 3 years of follow-up. Among RYGB patients, concurrent HHR was associated only with an increased risk of endoscopy (aHR, 1.4; 95% CI, 1.1–1.8) at 1 year of follow-up, persisting at 3 years. Although higher rates of endoscopy could signify GERD symptoms in the HHR groups, the finding that bariatric conversions/ revisions were very rare (and did not differ by HHR status) out to 3 years after surgery is reassuring, particularly among SG patients, that GERD symptoms (if present) were not leading to numerous conversions.


In addition, a 2018 analysis found no difference in 30-day adverse event rates in MBS patients with and without concurrent paraesophageal hernia repair (PEH) status. (Shada et al. Concurrent bariatric surgery and paraesophageal hernia repair: comparison of sleeve gastrectomy and Roux-en-Y gastric bypass. Surg Obes Relat Dis 2018;14(1):8–13.]. Similarly, a 2019 Metabolic and Bariatric Surgery Association Quality Improvement Program (MBSAQIP) registry study found no increased risk of 30-day adverse events associated with concurrent PEH repair (1.1% event rate without PEH and 1.2% with PEH) (Hefler et al. Concurrent bariatric surgery and paraesophageal hernia repair: an analysis of the Metabolic and Bariatric Surgery Association Quality Improvement Program (MBSAQIP) database. Surg Obes Relat Dis 2019;15(10):1746– 54).


A second MBSAQIP study registry observed higher rates of 30-day reoperation (1.1% versus .8%), readmission and overall morbidity among SG patients with HHR compared with propensity-matched SG-only patients (Janik et al. Safety of concurrent sleeve gastrectomy and hiatal hernia repair: a propensity score-matched analysis of the MBSAQIP registry. Surg Obes Relat Dis 2020;16(3):365–71). In a recent meta-analysis on the effect of LSG and HHR a total of 18 studies totaling 937 patients were included (Chen et al. Effect of Concomitant Laparoscopic Sleeve Gastrectomy and Hiatal Hernia Repair on Gastroesophageal Reflux Disease in Patients with Obesity: a Systematic Review and Meta-analysis. Obes Surg. 2021 Sep;31(9):3905-3918).The results of metaanalysis showed that after SG+ HHR, there was a significant reduction in GERD symptoms (OR: 0.20; 95% CI: 0.10 to 0.41; P < 0.00001), improvement in esophagitis (OR: 0.12, 95% CI: 0.05 to 0.26, P < 0.001), and decrease in GERD-HRQL (MD: 19.13, 95% CI: −3.74 to 34.51; P=0.01).


Angrisani concluded that MBS should be considered as the preferred method to achieve clinically significant weight loss in metabolically challenged patients/High BMI even though comorbidities (type 2 diabetes mellitus, NASH syndrome, nephritis, heart failure) increase their risk of operative and postoperative complications.


The first aim of metabolic and bariatric surgery should be to ensure patient safety. Due to anatomical difficulties (thicker abdominal walls, larger livers with fatty infiltration, and considerably greater amounts of perivisceral fat), poor visualisation of the operative field and anaesthesia-related problems, a two-step approach by performing a technically easier procedure and then an RYGB or BPD-DS and SADI-S (when necessary) should be the preferred surgical strategy.


The choice of the second step procedure remains controversial. In a metabolically challenged patient, hypoabsorptive procedures – especially those involving a duodenoileostomy –should only be performed by experienced surgeons at high-volume centres.

In the case of a hiatal hernia, it should be repaired independently of the type of approach (1 or 2 steps) or the type of operation.


Professor Angrisani acknowledged the contribution of Dr Rossella Palma, Endoscopic Surgeon and PhD in Hepato-Gastroenterology at “Sapienza" University of Rome, Italy, in researching and preparing his presentation.

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