Modifications to the WHODAS-II for the World Mental Health Surveys: Lessons Learned.

Objective The WHODAS-II was substantially modified for use in the World Mental Health Surveys. This paper considers the modified WHODAS-II’s psychometric properties and implications of filter items employed to reduce respondent burden. Study design and setting Seventeen Surveys in 16 Countries administered a modified WHODAS-II to population samples (N=38,934 Adults). Modifications included introducing filter questions for four sub-scales and substituting questions on the number of days activity was limited for the life activities domain. We evaluated distributional properties, reliability, and validity of the modified WHODAS-II. Results Most respondents (77%–99%) had zero scores on filtered subscales. Lower bound estimates of internal consistency (alpha) for the filtered subscales were typically in the 0.70’s, but were higher for the Global scale. Loadings of subscale scores on a Global Disability factor were moderate-to-high. Correlations with the Sheehan Disability Scale were modest but consistently positive, while correlations with SF-12 Physical Component Summary were considerably higher. Cross-national variability in disability scores was observed, but was not readily explainable. Conclusions Internal consistency and validity of the modified WHODAS-II was generally supported, but use of filter questions impaired measurement properties. Group differences in modified WHODAS-II Disability scores may be compared within, but not necessarily across, countries.
Reference: Journal of Clinical Epidemiology, 61(11), 1132-1143. https://doi.org/10.1016/j.jclinepi.2007.12.009 .
Keywords: Disability,Measurement,Reliability,Validity,Survey,Epidemiology,WHO-DAS

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