Predictive Factors of Cholelithiasis After Prophylactic Administration of Ursodeoxycholic Acid Following Laparoscopic Bariatric Surgery: Tehran Obesity Treatment Study

Purpose Cholelithiasis is a well-known consequence of obesity as well as rapid weight loss especially after bariatric surgery. A routine postoperative course of ursodeoxycholic acid (UDCA) is recommended as a prophylactic measure against gallstone formation. However, the efficacy of UDCA after bariatric surgery and predictors of cholelithiasis despite prophylaxis are not well understood. We assessed the incidence and predictors of de novo cholelithiasis after bariatric surgery in patients who received UDCA prophylaxis. Methods Uniform data from 2629 consecutive patients who underwent either sleeve gastrectomy or gastric bypass between March 2013 and 2018 were collected prospectively. All patients received a 6-month course of UDCA 300 mg twice daily. Cholelithiasis was assessed with abdominal ultrasound at baseline as well as 6, 9, 12, 18, and 24 months postoperatively. The association between cholelithiasis and its predictors was examined by Cox proportional hazards models and restricted cubic spline regression. Results The cumulative rate of cholelithiasis in 24 months after surgery was 10.8% ( n = 283) with the greatest incidence within the first year. After multivariate analysis, 6-month body mass index (BMI) loss was found to be the only independent predictor for postoperative cholelithiasis (HR = 1.10 [95% CI: 1.04–1.16]). The concordance index for predicting cholelithiasis was 0.60 (0.56–0.64) for 6-month BMI loss. Conclusion Early postoperative rapid weight loss as represented by 6-month BMI loss is the main predictor of de novo cholelithiasis after bariatric surgery, although this parameter does not have enough power for discrimination of postoperative cholelithiasis. Graphical abstract