Utility of the twelve-item World Health Organization disability assessment schedule II (WHO-DAS II) for discriminating depression "caseness" and severity in Spanish primary care patients

Purpose: The 12-item WHO-DAS II was developed to assess the activity limitations and participation restrictions experienced by individuals irrespective of medical diagnosis. In this paper we examine the known-groups' validity of the instrument by evaluating its ability to discriminate between patients with/without major depression, patients with depression with/without medical comorbidity, and patients with depression with different depression severity. Method: The participants were 3,615 PC patients from 17 regions of Spain, with a first-time diagnosis of major depressive episode according to the general practitioner. The 12-item WHO-DAS II, the PHQ-9, and a chronic medical conditions checklist were administered during the consultation. Results: The statistical analyses indicated that the 12-item WHO-DAS II was able to discriminate between patients with/without depression and between those with different depression severity. The ROC analysis revealed that with a cutoff score ≤50, the instrument correctly classified 70.4% of the sample (area under the ROC curve = .76; sensitivity = 71.4%; specificity = 67.6%). Conclusions: Overall, our results support the discriminant validity of the 12-item WHO-DAS II for major depression, being quite recommendable its use in epidemiological research.