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

Objective: To evaluate the reliability and validity of WHODAS II within the spinal cord injury population.

Subjects: Sixty-three people with traumatic spinal cord injury.

Methods: 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.

Results: 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.

Conclusion: 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.