Depression and excess mortality: evidence for a dose response relation in community living elderly.

CONTEXT

Depression is associated with an increased mortality risk. It is not known to what extent depression characteristics such as severity and length of exposure to depression contribute to the association with excess mortality.

OBJECTIVES

To investigate the association between depression severity and duration with mortality in community-living elderly.

DESIGN

Two-wave prospective cohort study with 10-year follow-up of vital status. Assessment of depression at baseline and at three year follow-up (GMS-AGECAT). Cox proportional hazards analyses of mortality with depression according to severity and length of exposure, adjusted for demographic variables, physical illnesses, cognitive decline and functional disabilities.

SETTING AND PARTICIPANTS

Randomly selected cohort of 3 746 non-demented older community-living persons in the city of Amsterdam.

MAIN OUTCOME MEASURES

Excess mortality of both the baseline cohort, and of non-demented subjects participating in both assessments (n = 1989).

RESULTS

Both moderate (MHR 1.29, 95% CI 1.03-1.61) and severe depression (MHR 1.34, 95% CI 1.07-1.68) predicted 10-year mortality after multivariate adjustment. Chronic depression was associated with a 41% higher mortality risk in 6-year follow-up compared to subjects without depression.

CONCLUSIONS

Severity and chronicity of depression are associated with a higher mortality risk. In combination with other findings this is suggestive of a causal relationship and may have implications for both preventive and treatment strategies of late-life depression.