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Randomized Controlled Trial
. 2025 Apr 1;160(4):369-377.
doi: 10.1001/jamasurg.2024.7052.

Long-Term Outcomes of Laparoscopic Roux-en-Y Gastric Bypass vs Laparoscopic Sleeve Gastrectomy for Obesity: The SM-BOSS Randomized Clinical Trial

Marko Kraljevic  1 , Julian Süsstrunk  1 , Bettina Karin Wölnerhanssen  2   3 , Thomas Peters  4 , Marco Bueter  5 , Daniel Gero  5 , Bernd Schultes  6 , Adisa Poljo  1 , Romano Schneider  1 , Ralph Peterli  1   3
Affiliations
Randomized Controlled Trial

Long-Term Outcomes of Laparoscopic Roux-en-Y Gastric Bypass vs Laparoscopic Sleeve Gastrectomy for Obesity: The SM-BOSS Randomized Clinical Trial

Marko Kraljevic et al. JAMA Surg. .

Abstract

Importance: Reports on long-term outcomes from randomized clinical trials comparing laparoscopic sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are scarce.

Objective: To compare long-term weight and metabolic outcomes, reoperation rates, and quality of life for patients undergoing SG vs RYGB at 10 years and beyond.

Design, setting, and participants: The SM-BOSS (Swiss Multicenter Bypass or Sleeve Study) randomized clinical trial was conducted from January 2007 to November 2011 at 4 bariatric centers in Switzerland. (The last follow-up was obtained in July 2023.) A total of 3971 patients with severe obesity were assessed, and 217 patients were enrolled and randomized to undergo SG or RYGB.

Interventions: Laparoscopic SG or RYGB.

Main outcomes and measures: The primary outcome of the SM-BOSS trial was the percentage excess body mass index loss (%EBMIL) at 5 years. The present study reports on the long-term weight and metabolic outcomes at 10 years and beyond, including changes in weight and obesity-related diseases, reoperation rates, and quality of life.

Results: Of 217 patients randomized to undergo SG or RYGB, mean (SD) age was 42.5 (11.1) years, mean (SD) baseline BMI was 43.9 (5.3), and 156 patients (71.9%) were female. Of 217 patients, 110 patients were randomized to RYGB and 107 to SG. Complete 10-year follow-up is available for 65.4% of patients. In the intention-to-treat population, mean (SD) %EBMIL was 60.6% (25.9) after SG and 65.2% (26.0) after RYGB (P = .29). Patients who underwent SG had significantly higher conversion rates because of insufficient weight reduction or reflux compared to RYGB (29.9% vs 5.5%; P < .001). Patients undergoing RYGB had significantly higher mean (SD) %EBMIL compared to SG after 10 years in the per-protocol (PP) population (65.9% [26.3] vs 56.1% [25.2]; P = .048). However, mean (SD) percentage total weight loss was not significantly different between groups (RYGB: 27.7% [10.8]; SG: 25.5% [15.1]; P = .37). SG patients had significantly more de novo gastroesophageal reflux (GERD) compared with RYGB (P = .02).

Conclusions and relevance: In the SM-BOSS randomized clinical trial, RYGB led to significantly higher %EBMIL in the PP population compared with SG beyond 10 years of follow-up, with better results for GERD. Patients undergoing SG experienced a significantly higher number of conversions to different anatomy compared with RYGB.

Trial registration: ClinicalTrials.gov Identifier NCT00356213.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Kraljevic reported grants from the Swiss National Science Foundation and from Ethicon Endo Surgery USA during the conduct of the study. Dr Schultes reported personal fees from Boehringer Ingelheim, Eli Lilly, and Novo Nordisk and advisory board and lecture fees from Johnson & Johnson outside the submitted work. Dr Peterli reported grants from the Swiss National Science Foundation and from Johnson & Johnson USA during the conduct of the study; personal fees paid to the institution from AstraZeneca, Johnson & Johnson Switzerland, Lilly, Medtronic, Novo Nordisk, and Viatris outside the submitted work. No other disclosures were reported.

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