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.
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.
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.
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.
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.