Background: Depression may be a potential risk factor for subsequent cardiac death. The impact of depression on cardiac mortality has been suggested to depend on cardiac disease status, and to be stronger among cardiac patients. This study examined and compared the effect of depression on cardiac mortality in community-dwelling persons with and without cardiac disease.
Methods: A cohort of 2847 men and women aged 55 to 85 years was evaluated for 4 years. Major depression was defined according to psychiatric DSM-III criteria. Minor depression was defined by Center for Epidemiologic Studies-Depression Scale scores of 16 or higher. Effects of minor and major depression on cardiac mortality were examined separately in 450 subjects with a diagnosis of cardiac disease and in 2397 subjects without cardiac disease after adjusting for demographics, smoking, alcohol use, blood pressure, body mass index, and comorbidity.
Results: Compared with nondepressed cardiac patients, the relative risk of subsequent cardiac mortality was 1.6 (95% confidence interval [CI], 1.0-2.7) for cardiac patients with minor depression and 3.0 (95% CI, 1.1-7.8) for cardiac patients with major depression, after adjustment for confounding variables. Among subjects without cardiac disease at baseline, similar increased cardiac mortality risks were found for minor depression (1.5 [95% CI, 0.9-2.6]) and major depression (3.9 [95% CI, 1.4-10.9]).
Conclusion: Depression increases the risk for cardiac mortality in subjects with and without cardiac disease at baseline. The excess cardiac mortality risk was more than twice as high for major depression as for minor depression.