The reliability and validity of the World Health Organization Disability Assessment Schedule (WHODAS-II) in stroke

Purpose: Psychometric properties of the World Health Organization Disability Assessment Schedule (WHODAS-II) in stroke have received some attention recently, mostly using classical approaches, but there is still an absence of investigation from a modern psychometric perspective. This study aimed to test the reliability and validity of the WHODAS-II in stroke, using modern psychometric analysis. Methods: A total of 188 community-dwelling poststroke patients were recruited. Internal construct validity was assessed by Rasch analysis, reliability by internal consistency and person separation index (PSI), and external construct validity by associations with Functional Independence Measure (FIM (TM)). Results: Rasch analysis indicated that total score (based upon 32 items, omitting the work-related items) was satisfactory, after adjustment for local dependency. The proposed "activities" and "participation" components also satisfied Rasch model expectations. An existing short form was problematic due to inclusion of a work-related item, but an alternative 10-item version was acceptable. Cronbach's a for the WHODAS-II, its domains and components varied between 0.83 and 0.99 and PSI between 0.70 and 0.95. External construct validity was confirmed by expected correlations with FIM (TM). Conclusions: WHODAS-II provides a reliable and valid instrument for measuring disability and components of "activities" and "participation" in stroke survivors. Various combinations of the item set may provide a range of scales to suit most research needs.