Cost-effective decisions in detecting silent common bile duct gallstones during laparoscopic cholecystectomy

Objective: To evaluate the cost-effectiveness of routine intraoperative ultrasonography (IOUS), cholangiography (IOC), or expectant management without imaging (EM) for investigation of clinically silent common bile duct (CBD) stones during laparoscopic cholecystectomy. Background: The optimal algorithm for the evaluation of clinically silent CBD stones during routine cholecystectomy is unclear. Methods: A decision tree model of CBD exploration was developed to determine the optimal diagnostic approach based on preoperative probability of choledocholithiasis. The model was parameterized with meta-analyses of previously published studies. The primary outcome was incremental cost per quality-adjusted life year (QALY) gained from each diagnostic strategy. A secondary outcome was the percentage of missed stones. Costs were from the perspective of the third party payer and sensitivity analyses were performed on all model parameters. Results: In the base case analysis with a prevalence of stones of 9%, IOUS was the optimal strategy, yielding more QALYs (0.9858 vs 0.9825) at a lower expected cost ($311 vs $574) than EM. IOC yielded more QALYs than EM in the base case (0.9854) but at a much higher cost ($1122). IOUS remained dominant as long as the preoperative probability of stones was above 3%; EM was the optimal strategy if the probability was less than 3%. The percentage of missed stones was 1.5% for IOUS, 1.8% for IOC and 9% for EM. Conclusions: In the detection and resultant management of CBD stones for the majority of patients undergoing laparoscopic cholecystectomy, IOUS is cost-effective relative to IOC and EM.