Validation of the World Health Organization Disability Assessment Schedule (WHO-DAS II) in Greek and its added value to the Short Form 36 (SF-36) in a sample of people with or without disabilities

BackgroundThere is controversy and ongoing interest on the measurement of functionality in the personal and social level.Objectives(1) to validate the Greek version of the World Health Organization Disability Assessment Schedule (WHO DAS II) and (2) to determine its added value to the physical and psychological health subscales of the Short Form 36 (SF-36).MethodsIn a cross-sectional design, data were collected between December 2014 and March 2015 by using three questionnaires (WHO DAS II, SF-36, PSS-14) in a sample of people with disabilities (n = 101) and without disabilities (n = 109) in Athens, Greece. WHO DAS II internal consistency, construct and criterion-related validity were assessed by Cronbach alpha, exploratory factor analysis and correlations; its added value by multivariable linear regression.ResultsCronbach Alpha's were satisfactory for the WHO DAS II, PSS-14 and SF-36 (0.85, 0.88 and 0.96 respectively). Exploratory factor analysis confirmed the existence of one or two factors in people with or without disabilities, respectively. WHO DAS II score showed significant negative correlation with the physical and mental health scale of SF-36 score, especially strong for physical health while was positively related to PSS-14 score. In multivariate analysis mental health appraisal was related to perceived stress in both groups.ConclusionsThis study support the validity of the Greek version of WHO DAS II and warranted its use in assessment and follow up of people with disabilities, contributing to the development of suitable policies to cover their needs and providing comparable data with other surveys using the same instrument.