P-230 Cost effectiveness of Selective Internal Radiation Therapy (SIRT) using yttrium-90 resin microspheres for the treatment of patients with inoperable colorectal liver metastases in France

Abstract

Introduction: Treatment options for patients with chemotherapy-refractory metastatic colorectal cancer (mCRC) are limited. Selective internal radiation therapy (SIRT) using yttrium-90 (90Y)-labelled resin microspheres (SIR-Spheres; Sirtex, Sydney, Australia) has been shown to be a well-tolerated and effective treatment in patients with inoperable liver-dominant chemotherapy-refractory mCRC. The aim of this analysis was to assess the cost-effectiveness of SIRT with SIR-Spheres 90Y resin microspheres compared to best supportive care (BSC) from the perspective of the national health service in France. Methods: Survival data from a comparative retrospective cohort study of 90Y-resin microspheres vs. BSC in chemotherapy-refractory mCRC was analysed and used in a state-transition cost-effectiveness model, using Quality Adjusted Life Years (QALYs) gained as the measure of effectiveness. The model included costs for treatment acquisition, pre-treatment work-up and delivery of microspheres, and chemotherapy. Additionally, costs of managing adverse events and a cost of death were included. Utility data were taken from a recent NICE economic evaluation in mCRC. A wide range of sensitivity analyses were performed on utility, overall survival and costs. The one-way sensitivity analysis varied each parameter between its lower and upper bound and investigated the effect on the cost per QALY. The probabilistic analysis simultaneously sampled each parameter from its appropriate distribution (beta for utilities, normal for costs and multivariate normal for survival curve parameters) for 1,000 simulations and investigated the uncertainty around the cost per QALY. The scenario analysis explored alternative parametric curves for overall survival, alternative sources for utility values and alternative assumptions for the proportion of time spent in the pre- and post-progression health states. Results: The results show an increase in overall survival for patients receiving 90Y-resin microspheres compared to BSC by a mean of 1.15 life years (2.12 vs. 0.98 years), with a corresponding increase in quality adjusted life years (1.50 vs. 0.70). The associated costs for SIRT and BSC are €48,552 vs. €23,300, respectively. The additional costs are due to the SIRT treatment and the cost associated with extension to life. The cost per QALY is €30,610. Sensitivity analyses show that the model is robust to changes in parameters. Scenario analysis results demonstrate that the cost per QALY is not sensitive to alternative assumptions for survival curves, utilities or progression, varying only between €28,363 and €31,940. The one-way sensitivity analysis found that the parameters that had the biggest effect are those relating to the curve used to model overall survival. The probabilistic sensitivity analysis found that the probability of 90Y-resin microspheres being cost effective at a willingness-to-pay threshold of €33,506/QALY (1xGDP) is 69%. Conclusion: This analysis demonstrated that the use of 90Y-resin microspheres is a cost-effective option in the treatment of patients with chemotherapy-refractory liver-dominant mCRC in France. The results are robust to a wide range of sensitivity analyses, which ensures the predictability of the results.