Cost-effectiveness of tumor-treating fields added to maintenance temozolomide in patients with glioblastoma: an updated evaluation using a partitioned survival model.

A first cost-effectiveness analysis has raised a strong concern regarding the cost of tumor treatment fields (TTF) added to maintenance temozolomide for patients with glioblastoma. This evaluation was based on effectiveness outcomes from an interim analysis of the pivotal trial, moreover it used a "standard" Markov model. Our objective was to update the cost-effectiveness evaluation using the more flexible potential of the "partitioned survival" model design and using the latest effectiveness data. We developed the model with three mutually exclusive health states: stable disease, progressive disease, and dead. Good fit parametric models were developed for overall survival and progression free survival and these generated clinically plausible extrapolations beyond the observed data. We adopted the perspective of the French national health insurance and used a 20-year time horizon. Results were expressed as cost/life-years (LY) gained (LYG). The base case model generated incremental benefit of 0.604 LY at a cost of €453,848 which, after 4% annual discounting of benefits and costs, yielded an incremental cost effectiveness ratio (ICER) of €510,273/LYG. Using sensitivity analyses and bootstrapping methods results were found to be relatively robust and were only sensitive to TTF device costs and the modelling of overall survival. To achieve an ICER below €100,000/LYG would require a reduction in TTF device cost of approximately 85%. Using a different type of model and updated survival outcomes, our results show TTF remains an intervention that is not cost-effective, which greatly restrains its diffusion to potentially eligible patients.