Predictors of gallstone formation after bariatric surgery: a multivariate analysis of risk factors comparing gastric bypass, gastric banding, and sleeve gastrectomy.

Background: Risk factors for gallstone formation in the general population have been well studied while those after weight reduction surgery are unknown. The aim of this study was to identify the risk factors for the development of symptomatic gallstones after bariatric surgery.

Method: Retrospective review was performed for patients who underwent laparoscopic Roux-en-Y gastric bypass (RYGBP), adjustable gastric banding (LAGB) or sleeve gastrectomy (LSG) between 2004 and 2006. Statistical evaluation was performed using a univariate and multivariate analysis. Risk factors, including age, gender, preoperative body mass index (BMI), BMI > 45 kg/m(2), diabetes mellitus, hyperlipidemia, types of operation, and weight loss >25% of original weight, were analyzed for their association with postoperative symptomatic gallstones formation.

Results: 670 laparoscopic RYGBP, 47 LAGB, and 79 LSG were performed in our institute. Preoperative gallbladder disease, as indicated by presence of gallstones or sludge on preoperative transabdominal ultrasound, or previous cholecystectomy, were found in 25.3, 14.9, and 30.4% of patients who subsequently had RYGBP, LAGB, and LSG, respectively. A total of 586 patients were included for analysis. Mean follow-up was 25.9 (range 12-42) months. Overall rate of symptomatic gallstone formation was 7.8% and mean time for its development was 10.2 (range 2-37) months. Incidence of symptomatic gallstones with complications as initial presentation was found in 1.9% of the patients. Logistic regression analysis showed that only postoperative weight loss of more than 25% of original weight was associated with symptomatic gallstones formation [B = 1.482, SE = 0.533, odds ratio 4.44, 95% confidence interval (CI) 1.549-12.498, p = 0.005].

Conclusions: Traditional risk factors for gallstone formation in the general population are not predictive of symptomatic gallstone formation after bariatric surgery. Weight loss of more than 25% of original weight was the only postoperative factor that can help selecting patients for postoperative ultrasound surveillance and subsequent cholecystectomy once gallstones were identified.