What Difference Does It Make? A Comparison of Health State Preferences Elicited From the General Population and From People With Multiple Sclerosis

Abstract

Background: A major debate in the quality-adjusted life-year (QALY) literature concerns whose preferences should be used to estimate health state values (HSVs) and to calculate QALYs. Objectives: This study explores differences between public and patient values for multiple sclerosis (MS) health states, described using an MS-specific classification system (Multiple Sclerosis Impact Scale–8 Dimensions [MSIS-8D]). Methods: The MSIS-8D is an existing preference-based measure of health-related quality of life in MS, which has 2 tariffs of HSVs, based on the preferences of a representative sample of the UK general population (n = 1702) and of people with MS living in the United Kingdom (n = 1635), elicited using the time trade-off technique. Here, we explore differences between HSVs by sample type, using descriptive statistics and multivariate regression methods. Results: Overall, the survey of people with MS produced significantly higher HSVs; estimated values ranged from 0.079 to 0.883 for the general population survey and from 0.138 to 0.894 for the MS survey. Differences in HSVs were more pronounced for severe health states. The difference between patient and public values varied across the dimensions of the MSIS-8D. People with MS placed greater importance on cognition than the general population, leading to lower HSVs when impairment was at a worse level; the reverse was true for the daily activities, fatigue, and depression dimensions. Conclusions: We identified significant differences in HSVs by sample type. Using patient rather than public values may influence the results of economic evaluations, depending on the dimensions of health-related quality of life affected by the intervention being assessed, and may therefore have important consequences for reimbursement decisions.