Bidirectional Association Between Depression and Metabolic Syndrome: A systematic review and meta-analysis of epidemiological studies

OBJECTIVE: Epidemiological studies have repeatedly investigated the association between depression and metabolic syndrome (MetS). However, the results have been inconsistent. This meta-analysis aimed to summarize the current evidence from cross-sectional and prospective cohort studies that evaluated this association. RESEARCH DESIGN AND METHODS: MEDLINE, EMBASE, and PsycINFO databases were searched for articles published up to January 2012. Cross-sectional and cohort studies that reported an association between the two conditions in adults were included. Data on prevalence, incidence, unadjusted or adjusted odds ratio (OR), and 95% CI were extracted or provided by the authors. The pooled OR was calculated separately for cross-sectional and cohort studies using random-effects models. The I(2) statistic was used to assess heterogeneity. RESULTS: The search yielded 29 cross-sectional studies (n = 155,333): 27 studies reported unadjusted OR with a pooled estimate of 1.42 (95% CI 1.28–1.57; I(2) = 55.1%); 11 studies reported adjusted OR with depression as the outcome (1.27 [1.07–1.57]; I(2) = 60.9%), and 12 studies reported adjusted OR with MetS as the outcome (1.34 [1.18–1.51]; I(2) = 0%). Eleven cohort studies were found (2 studies reported both directions): 9 studies (n = 26,936 with 2,316 new-onset depression case subjects) reported adjusted OR with depression as the outcome (1.49 [1.19–1.87]; I(2) = 56.8%), 4 studies (n = 3,834 with 350 MetS case subjects) reported adjusted OR with MetS as the outcome (1.52 [1.20–1.91]; I(2) = 0%). CONCLUSIONS: Our results indicate a bidirectional association between depression and MetS. These results support early detection and management of depression among patients with MetS and vice versa.