S759 One-Year Thrombotic and Mortality Outcomes After Gastric Bypass Versus Sleeve Gastrectomy: A Retrospective Cohort Study

Introduction: Bariatric surgery significantly reduces cardiometabolic risk, but its impact on thrombotic outcomes remains less well characterized. Gastric bypass and sleeve gastrectomy (SG) differ in their physiological effects, including alterations in venous stasis, coagulation, and systemic inflammation, all of which may influence thrombotic risk. This study aimed to compare 1-year thrombotic outcomes following gastric bypass versus SG using a large, real-world electronic health record network. Methods: We conducted a retrospective cohort analysis using the TriNetX Global Collaborative Network. Adult patients who underwent gastric bypass (Cohort 1) or sleeve gastrectomy (Cohort 2) were included. Propensity score matching (1:1) was performed using a greedy nearest-neighbor algorithm with a caliper of 0.1 pooled standard deviations. Matching variables included age, sex, race, and comorbidities such as type 2 diabetes, metabolic syndrome, hypertension, obesity, chronic kidney disease, nicotine dependence, and alcohol use. Outcomes evaluated over a 1-year period included mortality, disseminated intravascular coagulation (DIC), intracardiac thrombus, upper and lower extremity deep vein thrombosis (DVT), and pulmonary embolism (PE). Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Results: After matching, each cohort included 81,333 patients. Gastric bypass was associated with significantly higher odds of DIC (OR 2.06, 95% CI 1.41–3.02), intracardiac thrombus (OR 1.81, 95% CI 1.15–2.83), upper extremity DVT (OR 1.70, 95% CI 1.01–2.89), and pulmonary embolism (OR 1.22, 95% CI 1.05–1.41) compared to sleeve gastrectomy. No significant difference was observed in lower extremity DVT (OR 1.07, 95% CI 0.97–1.18). Mortality was significantly higher in the gastric bypass group (OR 2.29, 95% CI 1.94–2.71). Conclusion: Gastric bypass is associated with increased thrombotic risk—including DIC, intracardiac thrombi, upper extremity DVT, and pulmonary embolism—compared to sleeve gastrectomy. These findings may reflect the greater physiological stress, altered coagulation dynamics, and longer operative time associated with bypass. The lack of difference in lower extremity DVT suggests that bypass may influence more systemic or atypical thrombotic pathways. These results underscore the importance of individualized thromboprophylaxis, vigilant postoperative monitoring, and consideration of thrombotic history when selecting a bariatric procedure.