The development and validation of the impact of multiple sclerosis scale and the symptoms of multiple sclerosis scale

<b>Objective</b><br /><br />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.<br /><b>Design</b><br /><br />Panel design involving test-retest over 4 months.<br /><b>Setting</b><br /><br />A mailed survey.<br /><b>Participants</b><br /><br />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.<br /><b>Interventions</b><br /><br />Not applicable.<br /><b>Main Outcome Measures</b><br /><br />Principal components analyses, the Cronbach α, 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.<br /><b>Results</b><br /><br />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.<br /><b>Conclusions</b><br /><br />The IMSS and SMSS are psychometrically sound scales suitable for clinical and research purposes to assess the symptoms and impact of MS.<br />