Validity, reliability, and responsiveness of the Brazilian version of the instrument World Health Organization Disability Assessment Schedule (WHODAS 2.0) for individuals with obstructive sleep apnoea

Abstract

Background: Obstructive sleep apnoea (OSA) is a disabling health condition, and there is no disease-specific patient-reported outcome instrument to assess individuals with OSA.

Objectives: To evaluate the psychometric properties of the Brazilian version of the World Health Organization Disability Assessment Schedule (WHODAS 2.0) in individuals with OSA.

Methods: One hundred individuals with OSA responded to the WHODAS 2.0 version of 36 items, the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI), and the 12-item health survey (SF-12). Internal consistency, convergent and discriminative validity, and responsiveness to continuous positive airway pressure (CPAP) were the psychometric properties tested.

Results: Cronbach's α values indicate good internal consistency (0.91 - 0.73), except for the self-care domain (α = 0.52). Convergent validity indicated an excellent correlation (r = -0.80) between the domains of functioning and quality of life. Discriminative validity showed no association between OSA severity and functioning (p = 0.90). The responsiveness to CPAP treatment showed a large effect size (r = 0.82; p < 0.05) CONCLUSIONS: The WHODAS 2.0 instrument is valid, reliable, and responsive for assessing individuals with OSA.

Keywords: Disability; International classification of functioning, disability, and health; Obstructive sleep apnoea; Psychometry; Validation study.