Depression and risk of mortality in individuals with diabetes: a meta-analysis and systematic review

Objectives To estimate risk of comorbid depression on all-cause mortality over time among individuals with diabetes. Methods The Medline, Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, Embase and Science Direct databases were searched through September 30, 2012. We limited our search to longitudinal or prospective studies reporting all-cause mortality among those having depression and diabetes, compared with those having diabetes alone that used hazard ratios (HRs) as the main outcome. Two reviewers independently extracted primary data and evaluated the quality of studies using predetermined criteria. The pooled random effects adjusted HRs were estimated using meta-analysis. The impact of moderator variables on study effect size was examined with meta-regression. Results A total of 42,363 respondents from 10 studies were included in the analysis. Depression was significantly associated with risk of mortality (pooled HR=1.50, 95% confidence interval=1.35–1.66). Little evidence for heterogeneity was found across the studies (Cochran Q=13.52, P =.20, I 2 =26.03). No significant possibility of publication bias was detected (Egger's regression intercept=0.98, P =.23). Conclusion Depression significantly increases the risk of mortality among individuals with diabetes. Early detection and treatment of depression may improve health outcomes in this population.