OBJECTIVE: To develop and validate the Impact of Multiple Sclerosis Scale (IMSS) and the Symptoms of Multiple Sclerosis Scale (SMSS) using the Extended Disability Status Scale (EDSS) for construct validity.DESIGN: Panel design involving test-retest over 4 months.SETTING: A mailed survey.PARTICIPANTS: Volunteers with a diagnosis of multiple sclerosis (MS) recruited from an MS support service in Australia: 193 people (mean age, 39y) and 150 people participated at time 1 and time 2, respectively.INTERVENTIONS: Not applicable.MAIN OUTCOME MEASURES: Principal components analyses, the Cronbach alpha, and descriptive statistics for the 2 scales; correlations for construct validity with the EDSS and retest; and confirmatory factor analysis to test the stability of IMSS and SMSS components over time.RESULTS: The IMSS yielded 5 independent and reliable components; the SMSS yielded 3 components; both component structures were stable over time. These scales showed convergent validity with the EDSS.CONCLUSIONS: The IMSS and SMSS are psychometrically sound scales suitable for clinical and research purposes to assess the symptoms and impact of MS.
Adult Data Interpretation, Statistical