Model-based Cost-utility Analysis of Gemcitabine, Cisplatin, and S-1 As Triple Therapy for Advanced Biliary Tract Cancer

Background: The results of the KHBO1401-MITSUBA trial suggest the effectiveness of triple therapy using gemcitabine, cisplatin, and S-1; however, the cost-effectiveness of this treatment regimen remains unclear.

Aim: We conducted a cost-utility analysis comparing triple therapy using gemcitabine, cisplatin, and S-1 with doublet therapy using gemcitabine and cisplatin for advanced biliary tract cancer from the perspective of a Japanese healthcare payer to investigate the economic sustainability of healthcare interventions.

Method: Based on the results of the KHBO1401-MITSUBA clinical trial, a partitioned survival model set over a 10-year time horizon was developed. Cost and utility data were sourced from previous studies. Health outcomes were measured as quality-adjusted life years (QALYs). Direct medical costs included drug costs and medical fees. The uncertainty and robustness of the model were evaluated using one-way and probabilistic sensitivity analyses. The willingness-to-pay threshold was set at 7.5 million Japanese yen (68,306 US dollars).

Results: Base case analysis revealed an incremental cost-effectiveness ratio for triple therapy at 4,458,733 Japanese yen (40,608 US dollars) per QALY. One-way sensitivity analysis showed that the parameter variation in the overall survival curves for each therapy had impacts exceeding the threshold. According to probabilistic sensitivity analysis, triple therapy had an 83.1% chance of being cost-effective at the threshold, and the 95% credible interval for the incremental cost-effectiveness ratio was 4,382,972-4,514,257 JPY (39,918-41,113 US dollars).

Conclusion: Triple therapy using gemcitabine, cisplatin, and S-1 is cost-effective for the primary treatment of biliary tract cancer in the Japanese healthcare system.