Psychometric Properties of the 12-Item World Health Organization Disability Assessment Schedule (WHODAS 2.0), Greek Version: A Cross-Sectional Study on Applicants of Welfare Benefits.

INTRODUCTION: The International Classification of Functioning, Disability, and Health (ICF) provides a framework for the biopsychosocial model of disability and was developed by the World Health Organization (WHO). The World Health Organization Disability Assessment Schedule (WHODAS 2.0) is an ICF-based tool that measures health and disability at the population level or in clinical practice. The aim of the study was to examine the psychometric properties of the Greek version of the WHODAS 2.0 (12-item) administered to 10,163 adults who had applied for welfare benefits in three regions of Greece.

METHODS: The WHODAS 2.0, administered by interview was the primary outcome variable. Principal axis factoring (PAF) and confirmatory factor analysis (CFA) assessed the data fit to the model (construct validity). The correlation between Barema disability percentage (assessed by a three-member medical committee) and WHODAS 2.0 score and the correlation between WHODAS 2.0 score and the number of comorbidities were also examined (concurrent validity). Cronbach's alpha was used to assess the internal consistency of the questionnaire. Floor and ceiling effects were also examined.

RESULTS: Internal consistency was acceptable (Cronbach's alpha=0.918). A significant association was found between Barema disability percentage and the WHODAS 2.0 score. Factor analysis showed a clear two-factor solution (PAF and CFA), while no floor or ceiling effects were evident.

CONCLUSION: The Greek version of the 12-item WHODAS 2.0 was found to be reliable and valid in a wide sample of applicants for welfare benefits.