Validity and reliability of the MSQ LI in cognitively impaired patients with multiple sclerosis

Abstract

Multiple sclerosis (MS) has important effects on quality of life but it is unknown how cognitive impairment affects the ability to assess or report this. O ur objective was to determine whether cognitive impairment negatively affects the construct validity and the reliability of the Multiple Sclerosis Q uality of Life Inventory (MSQLI). A neuropsychological test batter y and the Multiple Sclerosis Functional C omposite (MSFC) were administered to a sample of 136 patients referred for cognitive testing by their neurologists. A ge, sex, educatio n and ethnicity-adjusted T scores were calculated for each cognitive variable. C ognitive impairment was defined as any T score less than the fifth percentile. The MSQ LI was administered prior to neuropsychological testing and readministered one to four weeks later. C orrelations between the MSFC and the SF-36 were determined and compared between the cognitively impaired and unimpaired groups as the main test of construct validity. Test -retest and internal consistency reliability of each of the scales were compared for the impaired and unimpaired groups. Seventy-six (56%) patients were cognitively impaired. C onstruct validity and internal consistency reliability did not differ between the cognitively impaired and unimpaired groups. Test -retest reliability was lower for the bladder and vision scales in the impaired group, but remained acceptable for the bladder scale (r >0.7). C ognitive impairment, a common MS manifestation, does not appear to reduce the reliability or validity of the MSQ LI as a patient self-report measure of health status and quality of life.