Suicide risk varies by subtype of affective disorder

A cohort study of mortality was conducted in which 4022 patients with affective disorder who were treated during 1976-1985 in a mental institution or community clinic operated by the province of Alberta, Canada, were followed to the end of 1985. Vital status was determined by record linkage to the Statistics Canada Mortality Data Base. There were 326 deaths altogether, 96 from suicide. The standardized mortality ratio (SMR) for all causes of death combined was 2.3, and for suicide the SMR was 26.0. The SMR was also elevated for mental, circulatory and respiratory disorders, but not for neoplasms. The principal objective of the study was to determine whether there was a gradient of increasing mortality risk across the following diagnostic subgroups: manic disorder, bipolar affective disorder and major depressive disorder. A trend was found for suicide but not for all causes of death combined. The pattern of risk persisted after adjustment for the covariates sex, age and marital status in a Cox regression analysis.