A Quality-Adjusted Life-Year Measure for Multiple Sclerosis: Developing a Patient-Reported Health State Classification System for a Multiple Sclerosis-Specific Preference-Based Measure

Combining factor analysis with conceptual mapping, and Rasch analysis with psychometric criteria, provides a valid method of constructing a classification system for an MS-specific preference-based measure. The next stage is to obtain preference weights so that the measure can be used in studies investigating MS.