Long-Term Outcomes of Laparoscopic Roux-en-Y Gastric Bypass vs Laparoscopic Sleeve Gastrectomy for Obesity

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.