Depression as a risk factor for mortality in patients with coronary heart disease: A meta-analysis

Background: Prospective studies on physically healthy subjects have shown an association between depression and the subsequent development of coronary heart disease (CHD). The relative risk in meta-analytic aggregation is 1.64 (confidence interval [CI], 1.29-2.08) for any CHD event. However, the adverse impact of depression on CHD patients has not yet been the subject of a meta-analysis. Objective: To quantify the impact of depressive symptoms (eg, BDI, HADS) or depressive disorders (major depression) on cardiac or all-cause mortality. We analyzed the strength of the relationship, the time dependency, and the differences in studies using depressive symptoms or a clinical diagnosis as predictors of mortality. Method: English and German language databases (Medline, PsycInfo, PSYNDEX) from 1980 to 2003 were searched for prospective cohort studies. Sixty-two publications were identified. The inclusion criteria were met by 29 publications reporting on 20 studies. A random model was used to estimate the combined overall effect as crude odds ratios (OR) or adjusted hazard ratios (HR [adj]). Results: Depressive symptoms increase the risk of mortality in CHD patients. The risk of depressed patients dying in the 2 years after the initial assessment is two times higher than that of nondepressed patients (OR, 2.24; 1.37-3.60). This negative prognostic effect also remains in the long-term (OR, 1.78; 1.12-2.83) and after adjustment for other risk factors (HR [adj], 1.76; 1.27-2.43). The unfavorable impact of depressive disorders was reported for the most part in the form of crude odds ratios. Within the first 6 months, depressive disorders were found to have no significant effect on mortality (OR, 2.07; Cl, 0.82-5.26). However, after 2 years, the risk is more than two times higher for CHD patients with clinical depression (OR, 2.61; 1.53-4.47). Only three studies reported adjusted hazard ratios for clinical depression and supported the results of the bivariate models. Conclusions: Depressive symptoms and clinical depression have an unfavorable impact on mortality in CHD patients. The results are limited by heterogeneity of the results in the primary studies. There is no clear evidence whether self-report or clinical interview is the more precise predictor. Nevertheless, depression has to be considered a relevant risk factor in patients with CHD.