Background: Although most studies examining the relationship between depression and mortality indicate that there is excess mortality in depressed subjects, this is not confirmed in all studies. Furthermore, it has been hypothesized that mortality rates in depressed men are higher than in depressed women. Finally, it is not clear if the increased mortality rates exist only in major depression or also in subclinical depression.
Methods: A meta-analysis was conducted to examine these questions. A total of 25 studies with 106,628 subjects, of whom 6416 were depressed, were examined. Both univariate and multivariate analyses were conducted.
Results: The overall relative risk (RR) of dying in depressed subjects was 1.81 (95% CI: 1.58-2.07) compared to non-depressed subjects. No major differences were found between men and women, although the RR was somewhat larger in men. The RR in subclinical depression was no smaller than the RR in clinical depression.
Limitations: Only RRs of mortality were examined, which were not corrected for important confounding variables, such as chronic illnesses, or life-style. In the selected studies important differences existed between study characteristics and populations. The number of comparisons was relatively small.
Conclusions: There is an increased risk of mortality in depression. An important finding of this study is that the increased risk not only exists in major depression, but also in subclinical forms of depression. In many cases, depression should be considered as a life-threatening disorder.