The 12-item Self-Report World Health Organization Disability Assessment Schedule (WHODAS) 2.0 Administered Via the Internet to Individuals With Anxiety and Stress Disorders: A Psychometric Investigation Based on Data From Two Clinical Trials

BACKGROUND: The World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) is a widespread measure of disability and functional impairment, which is bundled with the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) for use in psychiatry. Administering psychometric scales via the Internet is an effective way to reach respondents and allow for convenient handling of data. OBJECTIVE: The aim was to study the psychometric properties of the 12-item self-report WHODAS 2.0 when administered online to individuals with anxiety and stress disorders. The WHODAS 2.0 was hypothesized to exhibit high internal consistency and be unidimensional. We also expected the WHODAS 2.0 to show high 2-week test-retest reliability, convergent validity (correlations approximately .50 to .90 with other self-report measures of functional impairment), that it would differentiate between patients with and without exhaustion disorder, and that it would respond to change in primary symptom domain. METHODS: We administered the 12-item self-report WHODAS 2.0 online to patients with anxiety and stress disorders (N=160) enrolled in clinical trials of cognitive behavior therapy, and analyzed psychometric properties within a classical test theory framework. Scores were compared with well-established symptom and disability measures, and sensitivity to change was studied from pretreatment to posttreatment assessment. RESULTS: The 12-item self-report WHODAS 2.0 showed high internal consistency (Cronbach alpha=.83-.92), high 2-week test-retest reliability (intraclass correlation coefficient=.83), adequate construct validity, and was sensitive to change. We found preliminary evidence for a three-factorial structure, but one strong factor accounted for a clear majority of the variance. CONCLUSIONS: We conclude that the 12-item self-report WHODAS 2.0 is a psychometrically sound instrument when administered online to individuals with anxiety and stress disorders, but that it is probably fruitful to also report the three subfactors to facilitate comparisons between studies. TRIAL REGISTRATION: Clinicaltrials.gov NCT02540317; https://clinicaltrials.gov/ct2/show/NCT02540317 (Archived by WebCite at http://www.webcitation.org/6vQEdYAem); Clinicaltrials.gov NCT02314065; https://clinicaltrials.gov/ct2/show/NCT02314065 (Archived by WebCite at http://www.webcitation.org/6vQEjlUU8)