Health State Values Derived from People with Multiple Sclerosis for a Condition-Specific Preference-Based Measure: Multiple Sclerosis Impact Scale–Eight Dimensions–Patient Version (MSIS-8D-P)

Abstract

Objective: In economic evaluation, health outcomes are commonly quantified using quality-adjusted life-years (QALYs) derived from the preferences of a sample of the general population. It can be argued that this approach ignores the preferences of people with experience of the condition, and that patient preferences have a place in the valuation of health outcomes. Here we report the estimation of a preference-based index for an existing condition-specific preference-based measure for multiple sclerosis (MS), the MSIS-8D, based on the preferences of people with MS. Study design: Internet time trade-off (TTO) survey, eliciting preferences from people with MS. Methods: We elicited preferences from a sample of people with MS (N = 1635) across 169 MSIS-8D health states, using the TTO technique. We fitted ordinary least squares and random effects models to the survey data to estimate values for all health states described by the MSIS-8D. Results: The new patient-derived index (the MSIS-8D-P) provides values ranging from 0.893 for the best possible health state to 0.138 for the worst state. The MSIS-8D-P exhibits good discriminative validity, identifying expected significant differences between groups based on presence/absence of MS, type of MS, and duration since diagnosis. Conclusions: The MSIS-8D-P index of values for MS-specific health states provides an opportunity to estimate QALYs based on patient preferences, for use in economic evaluations of treatments for MS. More broadly, it adds to the methods and data available to consider the health-related quality of life of people with MS to inform resource allocation and individual-level decisions regarding treatments for MS.