Su1521 EARLY SINGLE-OPERATOR CHOLANGIOSCOPY ASSISTED ELECTROHYDRAULIC LITHOTRIPSY (SOC-EHL) IN THE MANAGEMENT OF DIFFICULT BILIARY STONES IS COST-EFFECTIVE WHEN COMPARED TO A DELAYED STEP-UP APPROACH TO SOC-EHL

Abstract

Single-operator cholangioscopy assisted electrohydraulic lithotripsy (SOC-EHL) is the current standard of care for the management of difficult bile duct stones with failed clearance using conventional endoscopic retrograde cholangiopancreatography (ERCP). This modality; however, is expensive and the optimal timing of its use, in terms of cost-effectiveness, in the management of difficult bile duct stone remains unclear. To determine the most cost-effective timing of SOC-EHL utilization in the endoscopic management of difficult common bile duct stones. Difficult stones were defined as having failed ductal clearance via standard ERCP. A decision model was developed assessing 3 strategies with progressively delayed sequences of SOC-EHL introduction in relation to initial failed ERCP, adopting a 6-month time horizon. Probability estimates for each health state were obtained from a systematic review of the literature. For each strategy, outpatients undergoing ERCP underwent different timings of SOC-EHL introduction with regards to the failed initial ERCP, and were followed for subsequent need for re-intervention, adverse events, need for surgery, and/or successful endoscopic ductal clearance. The unit of effectiveness was complete ductal clearance without need for surgery. Deterministic and probabilistic sensitivity analyses were performed varying sequentially or synchronously all 54 model variables across ranges spanning 30% of their respective values. Costs were expressed in 2018US$, based on national US data. The strategy of performing SOC-EHL at a next procedure following initial failed ERCP is the least expensive approach when compared to delaying SOC-EHL. This strategy costs US$18506 on average per patient with complete ductal clearance and save between US$390 to US$734 when compared to the other two strategies, which introduce SOC-EHL only at the second or third ERCP following the initial failed procedural attempt. Effectiveness is clinically comparable between the three strategies ranging from 97-99%. Deterministic and probabilistic sensitivity analyses show changes in the results with variations of probability assumptions but especially when varying costs of SOC-EHL, ERCP facility fees and failure rates. Although SOC-EHL is expensive, this analysis demonstrates that among patients who have failed a prior attempt at stone extraction, utilization of SOC-EHL at the first subsequent ERCP is most cost-effective when compared to its delayed introduction. The results however, can vary with changes in ERCP facility fees, the failure rates and SOC-EHL equipment costs.