Factors Influencing Risk of Premature Mortality in Community Cases of Depression: A Meta-Analytic Review

Abstract

Background. Depressive disorders are associated with substantial risk of premature mortality. A number of factors may contribute to reported risk estimates, making it difficult to determine actual risk of excess mortality in community cases of depression. The aim of this study is to conduct a systematic review and meta-analysis of excess mortality in population-based studies of clinically defined depression. Methods. Population-based studies reporting all-cause mortality associated with a clinically defined depressive disorder were included in the systematic review. Estimates of relative risk for excess mortality in population-representative cases of clinical depressive disorders were extracted. A meta-analysis was conducted using Stata to pool estimates of excess mortality and identify sources of heterogeneity within the data. Results. Twenty-one studies reporting risk of excess mortality in clinical depression were identified. A significantly higher risk of mortality was found for major depression (RR 1.92 95% CI 1.65–2.23), but no significant difference was found for dysthymia (RR 1.37 95% CI 0.93–2.00). Relative risk of excess mortality was not significantly different following the adjustment of reported risk estimates. Conclusion. A mortality gradient was identified with increasing severity of clinical depression. Recognition of depressive symptoms in general practice and appropriate referral for evidence-based treatment may help improve outcomes, particularly in patients with comorbid physical disorders.