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.