First-generation immigrants and hospital admission rates for psychosis and affective disorders: an ecological study in Ontario

Abstract

Objective: The immigrant population in Canada, and particularly in Ontario, is increasing. Our ecological study first assessed if there was an association between areas with proportions of first-generation immigrations and admissions rates for psychotic and affective disorders. Second, this study examined if area-level risks would persist after controlling for area socioeconomic factors in census-derived geographical areas-Forward Sortation Areas (FSAs)-in Ontario.

Methods: Ontario's inpatient admission records from 1996 to 2005 and census data from 2001 were analyzed to derive FSA rates of first admissions for psychotic disorders and affective disorders per 100 000 person-years. Negative binomial regression models were adjusted, first, for FSA age and sex and, second, also for FSA population density and average income.

Results: Using age- and sex-adjusted models, admission rates for psychotic disorders were higher in areas with greater proportions of immigrants. These areas were associated with lower admission rates for affective disorders. When FSA average income and population density were added to the models, the influence of immigrants was attenuated to nonsignificant levels in models predicting psychotic disorders admission rates. However, greater proportions of immigrants remained significantly protective when predicting rates of affective disorders.

Discussion: Our study provides insight about the influence of area-level variables on risk of admission for psychotic and affective disorders in high immigrant areas. There is a dearth of current Canadian research on immigrant admission for psychotic disorders at the individual or area level. Future area- and individual-level studies may better identify groups at risk and possible explanations.