Su1026 PATIENTS UNDERGOING CHEMOTHERAPY FOR BORDELINE RESECTABLE PANCREATIC CANCER CAUSING BILIARY OBSTRUCTION: HOW TO STENT WHILE AWAITING SURGERY? A COST-EFFECTIVENESS ANALYSIS

Abstract

Background: The initial stenting approach to patients with malignant obstruction attributable to a borderline pancreatic cancer scheduled to undergo chemotherapy while awaiting possible surgery remains controversial due to discrepant results in the literature. The aim of this study was to compare the use of 2 competing standard types of stents to treat borderline resectable pancreatic cancer with biliary obstruction wile receiving chemotherapy in view of possible surgery. A decision tree was created in this patient population to assess the two competing strategies of inserting a PS or an MS over a time horizon extending up to 15 months after start of chemotherapy to account for measuring impacts of possible complications during an average 6 month chemotherapy course up to the decision of whether the patient is a candidate for surgery or not. The possible scenarios following the insertion of the biliary stent were modeled until the patients were considered ready for the surgery or not. After the initial stent insertion, there is a possibility of complications which can resolve or not, with or without hospitalization. All patients undergo chemotherapy according cycles every 15 days that are suspended during the time of hospitalization, if a complication occurs, and are restarted one week later. The effectiveness measure is the probability of being ready for the surgery. Probabilities were provided by contemporary literature. Mean hospital costs and mean length of stay are derived from a national US database. Physician fees and drug costs are the national amounts provided by CMS. All costs are updated for 2018. MS is a dominant strategy being both US$2233 cheaper and 11% more effective than the PS alternative. The average costs per patient are US$9304 for MS and US$11538 for PS, associated with respective effectiveness probabilities of 96% and 84.7% (likelihood of being ready for surgery, 15 months after initial stent insertion). The probability of failure after first complication in the model that was fixed at 21% should fall below 5% for PS to no longer be dominated. PS would be then more efficient than MS but would remain more costly. The domination of MS over PS is not affected when varying any of the other 24 variables across their respective ranges. The probabilistic sensitivity analysis confirms the robustness of these results. At the time of stent insertion when managing biliary obstruction for borderline resectable pancreatic cancer patients undergoing chemotherapy while awaiting surgery, the current cost-effectiveness analysis shows that using an initial MS is less costly and more effective than choosing a PS. Deterministic and probabilistic sensitivity analyses confirm the dominance of MS over PS for all plausible values of probability and cost input variables.