Association between adiponectin levels and coronary heart disease and mortality: a systematic review and meta-analysis

BACKGROUND: Our aim was to systematically review prospective studies of the association of plasma adiponectin levels with the risk of coronary heart disease (CHD) events, cardiovascular mortality and all-cause mortality. METHODS: We searched Medline, EMBASE, the Cochrane Library and CINAHL for reports published through October 2011. Search terms included 'adiponectin' AND 'cardiovascular disease' OR 'mortality'. We included prospective studies lasting more than 1 year with plasma adiponectin levels at baseline and all-cause mortality and/or major cardiovascular morbidity and mortality as outcomes. We used a random-effects model to pool the data and conducted additional subgroup meta-analyses according to the pre-existence of CHD. Pooled relative risk (RR) was estimated by a 1-SD increase in the logarithmically transformed circulating adiponectin levels. RESULTS: A total of 24 prospective studies were included in the meta-analysis. The pooled RR of adiponectin for CHD events (23 studies) was 1.03 [95% confidence interval (CI): 1.00, 1.06]. In subgroup analyses, the RR of adiponectin was 0.99 (95% CI: 0.94, 1.03) for new-onset CHD (17 studies), but there was an increased risk (RR = 1.12, 95% CI: 1.04, 1.22) for CHD recurrence (seven studies). A 10% increased risk (RR = 1.10, 95% CI: 1.04, 1.16) of all-cause mortality (six studies) and a 14% increased risk (RR = 1.14, 95% CI: 1.05, 1.23) of cardiovascular disease mortality (five studies) were observed. CONCLUSIONS: No association was observed between adiponectin levels and CHD events. Our results suggest that higher circulating adiponectin levels may be associated with an increased risk of CHD recurrence and all-cause/CVD mortality.