Depression, depressive symptoms and mortality in persons aged 65 and over living in the community: a systematic review of the literature.

BACKGROUND: No recent attempt has been made to synthesize information on mortality and depression despite the theoretical and practical interest in the topic. Our objective was to estimate in the older population the influence on mortality of depression and depressive symptoms.
METHODS: Data sources were: Medline, Embase, personal files and colleagues' records. Studies were considered if they included a majority of persons aged > or = 65 years at baseline either drawn from a total community sample or drawn from a random sample from the community. Samples from healthcare facilities were excluded. Effect sizes were extracted from the papers; if they were not included in the published papers, effect sizes were calculated if possible. No attempt was made to contact authors for missing data.
RESULTS: We found 21 reports on 23 cohorts using depression diagnosis. For 15 of these, odds ratios were pooled using the Greenland method based on confidence intervals (CIs), giving an estimated odds ratio for mortality with depression of 1.73 (95% CI 1.53 to 1.95). A fixed effects meta-regression of these studies suggested that longer follow-up predicted smaller effect sizes (log odds ratios -0.096 per year (95% CI -0.179 to -0.014)). There is a weak suggestion of a reduced effect of depression on mortality for women. We were unable to pool effect sizes from the 17 studies using symptom totals and scales, or from eight studies of specific symptoms.
CONCLUSIONS: The studies show that diagnosed depression in community-resident older people is associated with increased mortality. The picture for sex differences is still unclear.