Angiotensin-converting enzyme gene polymorphism and carotid artery wall thickness a meta-analysis.

BACKGROUND AND PURPOSE: Many studies have investigated the association between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and carotid artery intima-media thickness (IMT); however, most studies were small and conducted in selective samples. The aim of this study was to evaluate this association by performing a meta-analysis on published articles. METHODS: We searched Medline for articles studying the association between the ACE I/D polymorphism and carotid IMT. Twenty-six studies were found; 23 articles containing 9833 subjects were qualified to enter the meta-analysis. We classified those articles on the basis of their samples into high-risk and low-risk populations and white and Asian ethnic groups. IMT was used as a continuous variable, and data were analyzed with the Cochrane Review Manager. RESULTS: A significant positive association was present between the D allele and common carotid IMT (weighted mean difference between DD and II genotypes, 0.23 mm x 10(-1); P<0.01). The association was stronger among high-risk populations. The point estimates of DD versus II were higher than those of ID versus II. CONCLUSIONS: Our meta-analysis showed evidence of a positive association between the D allele of the ACE gene and common carotid IMT. The overall results were concordant in both ethnic groups.