The World Health Organization Disability Assessment Scale, WHODAS II: reliability and validity in the measurement of activity and participation in a spinal cord injury population.

Abstract

To evaluate the reliability and validity of WHODAS II within the spinal cord injury population. Sixty-three people with traumatic spinal cord injury. The World Health Organization Disability Assessment Scale II (WHODAS II), Craig Handicap Assessment and Reporting Technique, and Medical Outcomes Study 36-item Short-Form Health Survey (MOS SF-36) were administered at 2 years post discharge from rehabilitation. Distribution, reliability, discriminant validity, and convergent/divergent validity were evaluated using classical tests. Rasch analyses were applied to assess dimensionality, item spread, and person/item reliability. Cronbach's alpha coefficients ranged from 0.61 (getting around) to 0.97 (participation). Ceiling effects were present in 4 out of 6 domains. WHODAS II discriminated between levels of impairment and work force status on 'self-care', 'getting around', 'life activities', and total score. Correlations with MOS SF-36 supported convergent/divergent validity. Five items didn't fit the Rasch model. The item/person map reveald a shortage of items able to differentiate the more able person. WHODAS II demonstrated good person and item separation and reliability. This study provides preliminary support for reliability and validity of WHODAS II in a spinal cord injured population. Limitations were noted for dimensionality and item person distribution. Findings need to be confirmed in larger samples.