Abstract 2634: French health utilities for patients with glioblastoma using TTFields
Authors: Chavez Gordon V. , Proescholdt Christina 
Published: July 2021

Abstract
Background: There is little real-world data available on Quality of Life (QoL) and health state utilities for patients with glioblastoma (GBM). The only standard utilities available were elicited from healthy panel members of the UK National Health System (Garside et al. 2007) rather than from actual patients with GBM. There are no utilities whatsoever for patients with GBM using Tumor Treating Fields (TTFields) therapy. We sought to provide the first health state utilities directly estimated from patients with GBM using TTFields.
Methods: We issued the EuroQol 5-Dimension (EQ-5D) survey to nearly 3,000 patients with GBM in the US and Europe who use TTFields treatment. Patient responses were completely anonymous and there was no other patient selection criteria. The EQ-5D is a validated and widely used tool for the evaluation of health related QoL and the estimation of health state utilities. We used a EuroQol-endorsed statistical model (Andrade et al. 2020) to estimate health state utilities from EQ-5D responses. This gives French tariffs i.e. utility values for application in French health economic evaluation. We sent an additional survey to collect data on age, disease progression status, time since diagnosis, treatment details, and other information.
Results: We report interim analysis on 906 survey responses, representing a response rate of 32%. This was notably higher than our target response rate of 20%. 853 of these EQ-5D responses were sufficiently complete to estimate utilities and 754 had complete information on age, progression status, and time from diagnosis. The overall sample median/mean utility estimates were .913/.836. The median/mean utility estimates for patients who had not experienced disease progression were .929/.882, while those for patients who had experienced disease progression were .855/.748. Of the patients who were non-progressed, 112 or 20.7% reported no problems on their EQ-5D survey, resulting in a utility estimate of 1, the highest possible value, indicating very good or fully satisfactory QoL. Of those patients whose disease had progressed, 22 or 9% similarly reported no problems. For non-progressed patients, older age was significantly negatively correlated with utility estimates, while for progressed patients this correlation was not significant. More notably, among patients who had experienced disease progression, longer time from diagnosis had a highly significant, positive effect on utility estimates.
Conclusion: High median utility estimates for both progressed and non-progressed patients, along with the percentage of patients reporting no problems, indicates that many patients with GBM using TTFields can expect a good Quality of Life. Additionally, in contrast to prevailing expectations and modeling assumptions, interim results indicate that utility and QoL of patients with GBM who have experienced disease progression is likely to increase with time.
Citation Format: Gordon V. Chavez, Christina Proescholdt. French health utilities for patients with glioblastoma using TTFields [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2634.