WHO Collaborative Study: An epidemiological survey of psychological problems in general health care in 15 centers worldwide

Abstract

This paper describes the epidemiological considerations in the design of a large longitudinal multi-center collaborative study which investigates the form, frequency, course and outcome of psychological problems commonly seen in primary health care settings in fifteen different sites around the world. The study used a two-stage sampling design: in the first stage the GHQ-12 was administered to 25,916 persons aged 18 to 65 consulting health care services. In the second stage 5,438 were selected for detailed examination using standardized instruments (Composite International Diagnostic Instrument-CIDI and WHO Social Disability Schedule). The sample was followed up at three months and one year to provide information on course and outcome. The project has produced a large database which examines multiple traits (symptoms and diagnosis, disability, management, outcome) using multiple methods (self-report, physician, and interviewer data), thus allowing the exploration of the nature of psychological disorders among general medical patients by comparing different measures. Some key findings of the study are summarized.