Measurement equivalence of the English and French versions of the self-efficacy to manage chronic disease scale: a Scleroderma Patient-Centered Intervention Network (SPIN) study

Purpose: The Self-Efficacy to Manage Chronic Disease (SEMCD) scale is widely used, including in systemic sclerosis (SSc). The SEMCD has been validated in SSc, but the metric equivalence of the English and French versions has not been assessed (i.e., whether psychometric properties are equivalent across English and French). Methods: Participants were adults from the Scleroderma Patient-Centered Intervention Network (SPIN) Cohort (N = 2159) who completed baseline measures in English (n = 1473) or French (n = 686) between May 2014 to July 2020. Analyses assessed internal consistency reliability via Cronbach’s alpha and McDonald’s omega, convergent validity via Pearson’s correlations, structural validity via confirmatory factor analysis (CFA), and differential item functioning via the Multiple-Indicator Multiple-Cause (MIMIC) model. Results: Internal consistency reliability was high in English (α =.93, ω =.93) and French (α =.92, ω =.93). All correlations between the SEMCD and measures of health outcomes were moderate to large, statistically significant, and in the hypothesized direction in both languages. The CFA demonstrated that the one-factor model of self-efficacy, overall, fit reasonably well (CFI =.96, TLI =.93, SRMR =.03, RMSEA =.14). Standardized factor loadings were large (.76 to.88). Three items displayed statistically significant uniform DIF and all six displayed nonuniform DIF; all DIF was of minimal magnitude. Comparison of unadjusted and DIF-adjusted models indicated that DIF did not meaningfully impact total score (ICC = 0.999, r = 0.999). Conclusion: Scores from English- and French-speaking adults with SSc can be combined for analysis or compared.