Objective To compare long-term survival rates and causes of death in community-dwelling elderly with and without depression using the International Research Diagnostic Criteria administered by a psychiatrist.
Method From 1985 to 2000, we prospectively examined Japanese persons (N = 920) aged 65 years or older. Cases with depression (n = 158) and a control sample without depression (N = 762) were evaluated. The main outcome variables were survival rates and causes of mortality.
Results By 2000, 61% of the subjects with depression had died. By contrast, 48% had died in the control group at the completion of the 15-year follow-up. Using age-adjusted Kaplan-Meier survival analysis, we found a hazard ratio (HR) of 1.49 (95% confidence interval [CI] 1.16-1.89) for mortality in the depressed group compared with controls (p = .0009). Importantly, in female subjects with depression, the HR was 1.55 (95% CI 1.16-2.07; p = .002). In males with depression, by contrast, the HR (1.34) was not significant (95% CI 0.84-2.13; p = .19). Significantly more subjects died of cerebrovascular disorders, malignant tumors, respiratory disorders, or suicide after the onset of depression compared with controls (p < .05).
Conclusions Depression appears to be associated with a significant increase in the risk of mortality among elderly Japanese subjects, particularly in females. The elderly with a diagnosis of depression may be at an elevated risk of mortality owing to cerebrovascular disorder, malignant tumors, respiratory disorders, or suicide. These prospective data provide a new quantitative insight on gender differences and the long-term public health significance of depression among the community-dwelling elderly.