Reliability and validity of the Multiple Sclerosis Quality of Life Inventory in older individuals

Abstract

Purpose: Despite the increasing number of older individuals with multiple sclerosis (MS), there is a paucity of research on this subpopulation. Health-related quality of life (HRQOL) has received extensive attention in MS; however samples tend to be young. The present study assesses the internal consistency reliability and construct validity of the MS Quality of Life Inventory (MSQLI), a widely employed measure of HRQOL, in older individuals. Method: Select subscales of the MSQLI and other measures of mental health and physical functioning were administered by telephone to 30 randomly selected older ( ⩾̸ 60) individuals and a gender-matched sample of younger ( < 60) individuals. Reliability estimates were calculated separately for each group. Construct (convergent) validity was assessed by examining the pattern of correlations between MSQLI subscales and measures of related constructs in the two groups. Results: Reliability estimates were similar in the two groups. With few exceptions, the correlations measuring convergent validity were in the expected direction, and of considerable magnitude, in both groups Conclusions: Results provide preliminary evidence that the MSQLI is a reliable and valid instrument for use with older individuals. The slightly different pattern of results observed in the validity analysis might be explained by an adjustment hypothesis. Future research on HRQOL in this subpopulation is encouraged.