Health-related quality of life in multiple sclerosis: psychometric analysis of inventories.

Objective: Measuring health-related quality of life (HRQoL) enables attainment of a comprehensive picture of chronic patients' conditions. The aim was to gain insight into HRQoL as viewed by Israeli multiple sclerosis (MS) patients, with an eye to its cross-cultural applicability, using psychometric analysis and a regression-based procedure.

Methods: The reliability and validity of the MSQoL-54 was assessed in 215 Israeli MS patients. Subsequently a novel method in QoL research for assessing the relative importance to patients of different aspects of the construct, comparing these between males and females, was applied. Using factor analysis, the degree to which the MSQoL-54 dimensions are applicable in our population and the existence of a separate dimension of Fatigue were tested. Finally, structural equation modelling (SEM) was used to examine relationships between QoL dimensions.

Results: The MSQoL-54 showed reliabilities and validities comparable to those found in other populations. Females attach importance to emotional aspects of QoL, while males are more concerned with physical aspects. The distinction between Emotional and Physical dimensions emerged from SEM, as did a distinction between Fatigue and Energy, the former being primarily Physical, and the latter Emotional. SEM indicated a reciprocal causality between Physical and Emotional dimensions.

Conclusions: Based on internal structure, reliability and validity, the MSQoL-54 is applicable to Israeli MS patients. However, the scale's Social Function dimension is indecisively defined, which requires further study. QoL research in MS should distinguish between emotional and physical Fatigue. Assessing importance of QoL dimensions should inform clinicians in tailoring treatment to the individual patient.