Association between copper levels and myocardial infarction: a meta-analysis

Background and aims: There are conflicting reports as to the correlation between copper (Cu) levels and myocardial infarction (MI). The purpose of the present study is to clarify the association between Cu levels and MI. Methods: We searched articles in Pubmed and the Chinese Journal Full-text Database published as of October 2014. A meta-analysis was used to pool estimates of the standardized mean difference (SMD) with 95% confidence interval (CI). Results: Pooled analysis indicated that subjects with MI had higher serum Cu levels than healthy controls (SMD = 1.629, 95% CI = [1.027, 2.232], Z = 5.30, p<0.001). Further subgroup analysis stratified by ethnicity indicated that subjects with MI had higher serum Cu levels than healthy controls among members of the Asian race (SMD = 2.191, 95% CI = [1.401, 2.981], Z = 5.43, p<0.001), but not among members of the Caucasian race (SMD = 0.411, 95% CI = [-0.030, 0.851], Z = 1.83, p = 0.068). The results obtained from hairs showed no association between MI and hair Cu levels (SMD = 0.338, 95% CI = [-0.171, 0.848], Z = 1.30, p = 0.193). But the subgroup analysis stratified by geological location indicated that subjects with MI had higher hair Cu levels than healthy controls in Pakistan (SMD = 0.785, 95% CI = [0.587, 0.983], Z = 10.29, p<0.001), but not in India (SMD = -9.028, 95% CI = [-10.747, -7.309], Z = 7.77, p<0.001). Conclusion: This meta-analysis indicates a significant association between high serum Cu levels and MI. However, the subgroup analysis found that there was significant effect modification of Cu levels by ethnicity. Thus, we suggest that a trans-regional multicenter study is needed to obtain better understanding of causal relationships between Cu and MI in different human races.