One-Year Prevalence of Psychiatric Disorder in Ontarians 15 to 64 Years of Age

Objective: To present the one-year prevalence of 14 psychiatric disorders in a community sample of Ontarians aged 15 to 64 years. Method: Data on psychiatric disorders were collected on 9953 respondents using the University of Michigan revision of the Composite International Diagnostic Interview (UM-CIDI). DSM-III-R criteria were used to define the psychiatric disorders. Results: Almost 1 in 5 Ontarians (18.6%) had one or more of the disorders measured in the survey. Among 15-to 24-year-olds, 1 in 4 was affected. The distribution of individual disorders varied by sex and age. Conclusion: Because of the immense burden of suffering associated with psychiatric disorders, clinical and research efforts in this area should receive high priority within the health budget. (Can J Psychiatry 1996;41:559-563) Key Words: psychiatric disorder, epidemiology, prevalence, community sample Unbiased, precise estimates of the prevalence of psychi-atric disorders in the general population can provide useful information on the magnitude and distribution of these conditions. Further, the combination of prevalence estimates and data on the utilization of mental health services will indicate the extent to which services are targeted accurately, give information on the extent of current need, and allow the identification of geographic areas that are relatively under- or overserviced. This paper presents one-year prevalence rates of psychiat-ric disorders from the Mental Health Supplement (the Sup-plement) to the Ontario Health Survey. The results are compared with 3 other community surveys of psychiatric disorders using lay interviewer-administered structured inter-views and DSM-III (1) or DSM-III-R (2) diagnostic criteria. The first, the Epidemiologic Catchment Area Study (3), was carried out in the early 1980s in 5 different sites in the United States. The sample included approximately 20 000 residents of 18 years of age or older from both household dwellings and institutions. The Diagnostic Interview Schedule (DIS) (4) was used to classify psychiatric disorders according to DSM-III criteria. The second survey (5), also using the DIS, wa