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

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 ( = 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.