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.