Assessing Stigma in Multiple Sclerosis: Psychometric Properties of the Eight-Item Stigma Scale for Chronic Illness (SSCI-8).

Abstract

Background\nThe stigma associated with neurologic disorders plays a part in poor health-related quality of life. The eight-item Stigma Scale for Chronic Illness (SSCI-8) is a brief self-assessment tool for measuring perceived level of stigma. The psychometric performance of the SSCI-8 in people with multiple sclerosis (MS) was assessed.\n\n\nMethods\nA multicenter, cross-sectional study in adults with relapsing-remitting or primary progressive MS was performed. A nonparametric item response theory procedure, Mokken analysis, was done to preliminarily study the dimensional structure of the SSCI-8. A confirmatory factor analysis (CFA) model was then fit, and the behavior and information covered by the eight items were assessed by parametric item response theory analysis.\n\n\nResults\nA total of 201 patients (mean ± SD age, 43.9 ± 10.5 years; 60.2% female; 86.1% with relapsing-remitting MS) were studied. The Mokken analysis found that the SSCI-8 is a unidimensional strong scale (scalability index H = 0.56) with high reliability (Cronbach α = 0.88). The CFA model confirmed the unidimensionality (comparative fit index = 0.975, root mean square error of approximation = 0.077). The information covered by the SSCI-8 items ranges from 3.79 to 13.52, for a total of 66.56. More than half (66%) of the SSCI-8 overall information is conveyed by four items: 1 ( Some people avoided me ), 2 ( I felt left out of things ), 3 ( People avoided looking at me ), and 7 ( People were unkind to me ).\n\n\nConclusions\nThe SSCI-8 shows appropriate psychometric characteristics and is, therefore, a useful instrument for assessing stigma in people with MS.