Further validation of the Multiple Sclerosis Self-Efficacy Scale

Abstract

Purpose: This study examined the factorial and construct validity of the Multiple Sclerosis Self-Efficacy (MSSE) Scale in two samples of people with multiple sclerosis (MS). Method: Two samples (n's = 292, 275) of participants with MS were recruited from across the United States. Participants in both studies completed a questionnaire battery that included the MSSE and measures of symptoms, dysfunction, disability, psychosocial aspects, mental/emotional well-being, and quality of life. Factorial validity was tested using confirmatory factor analysis (CFA), whereas construct validity was examined based on bivariate correlations with scores from other measures. Results: The two-factor measurement model provided a poor fit for the 18 items on the MSSE in both the samples. This model provided a good fit for a modified, 10-item scale in both samples. The 10-item version of the MSSE was highly correlated with the original MSSE (r = 0.97, p < 0.001) and related constructs (e.g. disability, r = 0.69, p < 0.0001). The standardized Cronbach's αs of the two subscales (function and control) of the 10-item version ranged between 0.78 and 0.94 for both samples. Conclusions: Scores from the modified, 10-item version of the MSSE provide a valid and reliable measure of MS-specific self-efficacy among persons with MS.

Implications for Rehabilitation

• The importance of self-efficacy in managing the consequences of multiple sclerosis (MS) has increased.

• The Multiple Sclerosis Self-Efficacy (MSSE) Scale was developed and validated for measuring self-efficacy in function maintenance and control over MS from patients' perspectives. In the past almost 20 years, this scale has not undergone additional validation of its factor structure and construct validity in large-scale samples of persons with MS.

• The original two-factor construct did not provide a good fit for the 18 items on the MSSE in two independent samples. We modified the MSSE and found the 10 items fitted by the two-factor construct well with one sample and demonstrated cross-validity of the 10 items in the second sample.

• The 10-item version of the MSSE has good reliability and construct validity in both independent samples. Researchers and clinicians should adopt these 10 items when examining MS self-efficacy of patients.

• Factor analysis, measurement, multiple sclerosis, psychometrics, self-efficacy

Declaration of interest

This investigation was supported, in part, by the United States Department of Health and Human Services, National Institutes of Health, National Institute of Neurological Diseases and Stroke (Grant NS054050). This research was further supported, in part, by a grant from the National Multiple Sclerosis Society (RG# 3926A2/1).