The effect of disease, functional status, and relapses on the utility of people with multiple sclerosis in the UK

Abstract

Objectives: Because published utility estimates in multiple sclerosis (MS) are concentrated in people with moderate to severe disease severity and focus on specific types of MS, we conducted a cross-sectional study of people with MS to estimate the utility associated with disease, functional status as measured by the Adapted Patient Determined Disease Steps (APDDS) Scale, and relapse to enhance knowledge of the association of these factors and utility. Methods: The study was conducted by a postal questionnaire sent to 12,968 people in a database managed by a UK charity (the MS Trust). Utility was assessed using the EQ-5D multiattribute utility scale. The APDDS is closely related to the more commonly reported Expanded Disability Status Scale (EDSS). Results: A total of 2708 (20.9%) questionnaires were returned and 2048 (15.8%) respondents provided data suitable for analysis. The mean age of the sample was 51 years, and 22.5% of people were aged 60 years or more. Disease severity was concentrated in people with moderately severe MS (EDSS 4-6.5), with 21%, 60%, and 19% of people reporting mild, moderate, and severe disease, respectively. Results show that disease severity has an inverse relationship with utility. The mean utility is 0.491. Utility varies between 0.870 and -0.195 for EDSS states 0 and 9. Number of years since diagnosis, type of disease, and recent relapse status are also all significantly associated with utility. Conclusions: The results are comparable with previous published utility estimates. We have demonstrated a clear relationship between functional status, disease type, relapse status, duration of illness, and utility. As a set of coefficients, the utility estimates we have calculated may be used to compare the quality of life of people with MS with other illnesses and to inform future economic evaluations in MS. © 2007, International Society for Pharmacoeconomics and Outcomes Research (ISPOR).