Relating health-related Quality of Life to disability progression in multiple sclerosis, using the 5-level EQ-5D

Background: Increasing use of the Quality-Adjusted Life-Year to inform resource allocation decision-making has highlighted the importance of relating clinical and health-related quality of life (HRQoL) outcomes in multiple sclerosis (MS) patients. Objective and Methods: To investigate the relationship between the Expanded Disability Status Scale (EDSS) and HRQoL utility, using the 5-level EQ-5D (EQ-5D-5L). The discriminatory power of the EQ-5D-5L was assessed using Shannon's indices. Results: A linear decline in utility was observed with changes in EDSS score from 0 to 6, after which point the relationship exhibited greater variability. Mean utility values ranged from -0.22 at EDSS 9 to 0.88 at EDSS 0. We found that the discriminative capacity of the EQ-5D-5L was considerably lower for the domains self-care and anxiety/depression, compared with other health-related domains. Conclusion: In its first reported use in an MS population, the EQ-5D-5L displayed good discriminatory capacity, although performance differed between the various domains of health, with evidence of a ceiling effect present in the domains of self-care and anxiety/depression. The EQ-5D-5L demonstrated a high correlation with EDSS in our MS cohort up to EDSS 6, after which point the utility valuation of severe health states exhibited much greater variability. Utility estimates from this study may be used in economic evaluations of disease-modifying therapies in MS, to inform resource-allocation decisions.