Psychometric evaluation of the Swedish self-rated 36-item version of WHODAS 2.0 for use in psychiatric populations – using classical test theory

Abstract

Aim The aim of this study was to evaluate the reliability and validity of the Swedish version of the self-rated 36-item WHODAS 2.0 in patients from Swedish psychiatric outpatient settings, using classical test theory. Methods The 36-item WHODAS 2.0, together with the Sheehan Disability Scale (SDS), was filled in by a sample of 780 participating psychiatric patients: 512 (65.6%) women, 263 (33.7%) men, and 5 (0.6%) who did not report any sex. Results The internal consistency, measured by Cronbach’s alpha, for the different domains of functioning were between 0.70 and 0.94, and interpreted as good. The confirmatory factor analysis (CFA) revealed two levels: the first level consisted of a general disability factor, while the second level consisted of the six domains of the scale, respectively. The model had borderline fit. There was a significant correlation between WHODAS 2.0 36-item and SDS (n = 395). The WHODAS 2.0 differed significantly between diagnostic groups. Conclusion The present study demonstrates that the Swedish self-rated 36-item version of WHODAS 2.0, within a psychiatric outpatient population, showed good reliability and convergent validity. We conclude that the self-rated 36-item Swedish version of WHODAS 2.0 can be used for valid interpretations of disability in patients with psychiatric health conditions.