Is SABR Cost-Effective in Oligometastatic Cancer? An Economic Analysis of SABR-Comet

M.X Qu,Y Chen,G Zaric,S Senan,R.A Olson,S Harrow,A John-Baptiste,S Gaede,L Mulroy,D Schellenberg,S Senthi,A Swaminath,N Kopek,M Liu,A Warner,G Rodrigues,D.A Palma,A.V Louie

doi:10.1016/j.ijrobp.2019.06.586

Abstract

The phase II randomized study SABR-COMET demonstrated that in patients with a controlled primary tumor and 1-5 oligometastatic lesions, SABR was associated with an improvement in both progression free survival and overall survival compared to standard of care. SABR is associated with higher costs and treatment-related toxicity. The aim of this study was to assess the cost-effectiveness of SABR versus standard of care in patients with oligometastatic disease. A Markov model was constructed to perform a cost-effectiveness analysis from the Canadian health care system perspective comparing SABR to standard of care. The model included the following health states: 1) Pre-progression; 2) Post-progression; 3) Death from cancer; 4) Death from adverse event; and 5) Non-cancer death. Utility values and transition probabilities were derived from individual-level data from the SABR-COMET trial. Overall survival and progression outcomes were internally and externally validated. Costs were obtained from the published literature and adjusted to 2018 Canadian dollars. Deterministic sensitivity analyses were performed to obtain thresholds at which each strategy would be preferred. Probabilistic sensitivity analysis was performed to assess the robustness of model. A lifetime horizon was used with a cycle length of 3 months. A willingness-to-pay threshold of $100,000/QALY was used. Quality adjusted life years (QALYs) and costs were discounted at a rate of 1.5%, as recommended in the Guidelines for the Economic Evaluation of Health Technologies: Canada. In the base case scenario, the SABR strategy provided 2.77 QALYs at a cost of $169,697 in comparison to 1.85 QALYs at a cost of $135,452 with the standard of care. SABR was therefore cost-effective in the base case, at an incremental cost-effectiveness ratio (ICER) of $37,250 / QALY. This finding was most sensitive to the number of metastatic lesions treated with SABR (ICER $28,137 – 64,587/QALY), the chemotherapy regimen (ICER $27,242-53,870/QALY), and hazard ratio of progression free survival between strategies (ICER $31,763-$53,908/QALY). Probabilistic sensitivity analysis revealed that SABR was a cost-effective strategy in 97% of the iterations. Based on this decision-analytic model created from a combination of literature and individual-patient clinical trial data, administering SABR is cost-effective for patients with 1-5 oligometastatic lesions compared to the standard of care.

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