Cross-cultural validity and reliability of the comprehensive assessment of acceptance and commitment therapy processes (CompACT) in people with multiple sclerosis

Purpose: The Comprehensive assessment of Acceptance and Commitment Therapy (CompACT) is a 23-item questionnaire measuring psychological flexibility, a quality of life protective factor. An 18-item version was recently produced. We assessed validity and reliability of CompACT, and equivalence of paper and electronic (eCompACT) versions in people with multiple sclerosis (PwMS) in Italy, Germany and Spain. Methods: We used confirmatory factor analysis and assessed CompACT-23 and CompACT-18 measurement invariance between the three language versions. We assessed construct validity (Spearman's correlations) and internal consistency (Cronbach’s alpha). Test–retest reliability (intraclass correlation coefficient, ICC) and equivalence of paper and eCompACT (ICC and linear regression model for repeated measures) were assessed in subsamples of PwMS. Results: A total of 725 PwMS completed the study. The three-factor structure of the CompACT-23 showed poor fit (RMSEA 0.07; CFI 0.82; SRMR 0.08), whi...