Disability in bipolar I disorder: the 36-item World Health Organization Disability Assessment Schedule 2.0

Abstract

Background: The WHODAS 2.0 is an ICF-based multidimensional instrument developed for measuring disability. The present study analyzes the utility of the 36-item interviewer-administered version in a sample of patients with bipolar disorder. There is no study to date that analyses how the scale works in a sample that only comprises such patients.

Methods: A total of 291 patients with bipolar disorder (42.6% males) according to DSM-IV-TR criteria from a cross-sectional study conducted in outpatient psychiatric clinics were enrolled. In addition to the WHODAS 2.0, patients completed a comprehensive assessment battery including measures on psychopathology, functionality and quality of life. Analyses were centered on providing evidence on the validity and utility of the Spanish version of the WHODAS 2.0 in bipolar patients.

Results: Participation domain had the highest percentage of missing data (2.7%). Confirmatory factorial analysis was used to test three models formulated in the literature: six primary correlated factors, six primary factors with a single second-order factor, and six primary factors with two second-order factors. The three models were plausible, although the one formed by six correlated factors produced the best fit. Cronbach's alpha values ranged between .73 for the Self-care domain and .92 for Life activities, and the internal consistency of the total score was .96. Relationships between the WHODAS 2.0 and measures of psychopathology, functionality and quality of life were in the expected direction, and the scale was found to be able to differentiate among patients with different intensity of clinical symptoms and work situation.

Limitations: The percentage of euthymic patients was considerable. However, the assessment of euthymic patients is less influenced by mood. Some psychometric properties have not been studied, such as score stability and sensitivity to change.

Conclusions: The Spanish version of the 36-item WHODAS 2.0 has suitable psychometric properties in terms of reliability and validity when applied to patients with bipolar disorder. Disability in bipolar patients is especially prominent in Cognition, Getting along, Life activities, and Participation domains, so functional remediation interventions should emphasize these areas in order to improve the daily living activities of these patients.

Keywords: Bipolar I disorder; Disability; Functioning; Health status; ICF; WHODAS 2.0.