Background: Depression has a high prevalence in the elderly population; however it often remains undetected. The WHO 5-item Well-Being Index (WHO-5) is a short screening instrument for the detection of depression in the general population, which has not yet been evaluated. The goals of the present study were: 1) to assess the internal and external validity of WHO-5 and 2) to compare the two recent versions of WHO-5.
Study population and methods: 367 subjects above 50 years of age were examined with the WHO-5. ICD-10 diagnoses were made using a structured interview (CIDI). The internal validity of the well-being index was evaluated by calculating Loevinger's and Mokken's homogeneity coefficients. External validity for detection of depression was evaluated by ROC analysis.
Results: The scale was sufficiently homogeneous (Loevinger's coefficient: version 1 = 0.38, version 2 = 0.47; Mokken coefficient > 0.3 in nearly all items). ROC analysis showed that both versions adequately detected depression. Version 1 additionally detected anxiety disorders, version 2 being more specific for detection of depression.
Conclusion: The WHO-5 showed a good internal and external validity. The second version is a stronger scale and was more specific for the detection of depression. The WHO-5 is an useful instrument for identifying elderly subjects with depression.