S266 Incidence of Postoperative Biliary Disease Following Bariatric Surgery: A Propensity-Matched Cohort Analysis of Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy

Introduction: Cholelithiasis and cholecystitis are common complications following rapid weight loss after bariatric surgery. While Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are both effective for obesity, their impact on biliary disease risk remains unclear. This study evaluated the incidence of biliary complications following RYGB vs SG in a matched cohort. Methods: Adult patients (≥18 years) with BMI ≥35 kg/m². Two surgical cohorts—RYGB and SG—were defined using CPT and SNOMED codes. Propensity score matching (1:1) yielded 13,566 patients per group. Outcomes of interest included gallstones (with and without cholecystitis) and cholecystitis-related complications. Results: After propensity score matching, 37,607 patients were included in each group. The overall cohort's mean ± SD age was 45.1 ± 11.4 years for the RYGB group and 45.3 ± 11.7 years for the sleeve group, with 77.5% and 77.0% women, respectively. The majority of patients were White (68.1.9% in the RYGB group vs 68.9% in the sleeve group) and not Hispanic or Latino (65.4% vs 66.0%). Matching achieved balance across cohorts (standardized difference <0.01). The risk of cholelithiasis was (0.12%% in the RYGB group vs 0.061% in the sleeve group; OR: 1.958, 95% CI: 1.184–3.236; P = 0.0076) over six months. The risk of cholecystitis was higher in the RYGB group compared to the sleeve group with statistically insignificant (0.035% vs 0.027%%; OR: 1.3, 95% CI: 0.57-2.965; P = 0.563). Over 1 year the risk of both outcomes were higher in RYGP (0.359% vs 0.247%; OR: 1.43, 95% CI: 1.157-1.896; P = 0.0053), (0.125% vs 0.08%; OR: 1.567, 95% CI: 0.991-2.471; P = 0.053) respectively. Conclusion: Among patients undergoing bariatric surgery, Roux-en-Y gastric bypass was associated with a significantly higher risk of developing cholelithiasis compared to sleeve gastrectomy. These findings highlight the need for proactive biliary monitoring and potential preventive strategies, such as screening with abdominal ultrasound or prophylactic cholecystectomy or medical therapy, particularly in RYGB patients at elevated risk.