The clinimetric properties of the World Health Organization Disability Assessment Schedule II in early inflammatory arthritis

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 >or=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.

Contribution of chronic diseases to disability in elderly people in countries with low and middle incomes: a 10/66 Dementia Research Group population-based survey

BACKGROUND

Disability in elderly people in countries with low and middle incomes is little studied; according to Global Burden of Disease estimates, visual impairment is the leading contributor to years lived with disability in this population. We aimed to assess the contribution of physical, mental, and cognitive chronic diseases to disability, and the extent to which sociodemographic and health characteristics account for geographical variation in disability.

METHODS

We undertook cross-sectional surveys of residents aged older than 65 years (n=15 022) in 11 sites in seven countries with low and middle incomes (China, India, Cuba, Dominican Republic, Venezuela, Mexico, and Peru). Disability was assessed with the 12-item WHO disability assessment schedule 2.0. Dementia, depression, hypertension, and chronic obstructive pulmonary disease were ascertained by clinical assessment; diabetes, stroke, and heart disease by self-reported diagnosis; and sensory, gastrointestinal, skin, limb, and arthritic disorders by self-reported impairment. Independent contributions to disability scores were assessed by zero-inflated negative binomial regression and Poisson regression to generate population-attributable prevalence fractions (PAPF).

FINDINGS

In regions other than rural India and Venezuela, dementia made the largest contribution to disability (median PAPF 25.1% [IQR 19.2-43.6]). Other substantial contributors were stroke (11.4% [1.8-21.4]), limb impairment (10.5% [5.7-33.8]), arthritis (9.9% [3.2-34.8]), depression (8.3% [0.5-23.0]), eyesight problems (6.8% [1.7-17.6]), and gastrointestinal impairments (6.5% [0.3-23.1]). Associations with chronic diseases accounted for around two-thirds of prevalent disability. When zero inflation was taken into account, between-site differences in disability scores were largely attributable to compositional differences in health and sociodemographic characteristics.

INTERPRETATION

On the basis of empirical research, dementia, not blindness, is overwhelmingly the most important independent contributor to disability for elderly people in countries with low and middle incomes. Chronic diseases of the brain and mind deserve increased prioritisation. Besides disability, they lead to dependency and present stressful, complex, long-term challenges to carers. Societal costs are enormous.

FUNDING

Wellcome Trust; WHO; US Alzheimer's Association; Fondo Nacional de Ciencia Y Tecnologia, Consejo de Desarrollo Cientifico Y Humanistico, Universidad Central de Venezuela.