Adiponectin Levels and Risk of Coronary Heart Disease: A Meta-analysis of Prospective Studies

Background: Adiponectin is the most abundant circulating protein secreted by adipocytes. There is uncertainty about the association between adiponectin levels and risk of coronary heart disease (CHD). We conducted this meta-analysis to summarize the effect of adiponectin on the risk of CHD. Methods: A comprehensive search was performed to identify all prospective studies on the association of adiponectin levels and risk of CHD. The quality of the eligible studies was evaluated by the Newcastle-Ottawa Scale. The fixed-or random-effects model was selected to pool the relative risk (RR) and 95% confidence interval (CI). Heterogeneity among studies was evaluated using Q test and the I-2 statistic. Publication bias was estimated using modified Egger's linear regression test. Results: Twelve prospective studies comprising 8 nested case-control studies and 4 cohort studies were included in the metaanalysis. A total of 14,960 participants were enrolled and 4,132 incident CHD events were observed. The pooled RR for CHD was 0.83 (95% CI, 0.69-0.98, P = 0.031). Subgroup analyses showed that the pooled RRs (95% CIs) for CHD risk were 0.78 (0.66-0.92) and 0.75 (0.59-0.94) for men and women, respectively. For studies with mean age less than 65 years, the pooled RR (95% CI) for CHD risk was 0.72 (0.59-0.87). For studies with 100 or more CHD cases, the pooled RR was marginally significant (RR 5 0.83, 95% CI, 0.69-1.00; P = 0.051). No publication bias was found in our study (P = 0.911). Conclusions: This meta-analysis showed that higher levels of adiponectin were associated with a low risk of CHD. The protective effect was consistently existed in men and women and in the middle-aged populations.