Objective: The aim of this study was to assess the psychometric properties of the Multiple Sclerosis Impact Scale (MSIS-29) for patients in the community and in a hospital setting.
Methods: During an epidemiological study, 172 people with multiple sclerosis (MS) were examined and completed the MSIS-29, the London Handicap Scale, and Beck's Depression Inventory; disability was assessed by the Kurtzke Expanded Disability Status Score (EDSS) and the Multiple Sclerosis Functional Composite. At the hospital neurology clinic, 102 MS patients completed the MSIS-29 and EDSS assessments were performed; 41 of these patients had repeat evaluations six months later. The psychometric properties of the MSIS-29 were examined.
Results: In the 172 community and the 102 hospital patients the psychometric properties of the MSIS-29 were satisfactory, with high convergent and low divergent validity. It was significantly responsive to change in the contexts of self-reported change (p<0.034) and EDSS worsening (p<0.001). The MSIS-29 physical score did not change over time when the EDSS was stable, and increased significantly in proportion to EDSS deterioration (p = 0.014).
Conclusions: The psychometric properties of the MSIS-29 are acceptable; it is a valuable outcome measure in intervention studies of patients with MS.