The relationship between lipids/lipoproteins and atherosclerosis in African Americans and whites: The atherosclerosis risk in communities study

PURPOSE: The relationships between lipids/lipoproteins and atherosclerosis were determined in African Americans and whites to assess the consistency o f the relationship between these two groups. Differences could suggest vary ing biological, environmental, or life-style cofactors influencing developm ent of atherosclerosis. METHODS: In the Atherosclerosis Risk in Communities Study, 2966 African Ame ricans and 9399 whites had determinations of LDL, HDL, HDL2, and HDL3 chole sterol, triglycerides, apolipoprotein A1 and B, and lipoprotein (a). Caroti d intimal-medial thickening (IMT) was measured using B-mode ultrasound imag ing. RESULTS: The associations, using linear regression, between carotid IMT and LDL cholesterol, HDL cholesterol, and other lipid measurements were signif icantly weaker in African Americans than whites. Averaging men and women, a 1.034 mmol/L (40 mg/dl) difference in LDL cholesterol was associated with a 0.028 mm IMT difference in whites but a 0.019 difference in African Ameri cans. Similarly, for HDL cholesterol, a 0.44 mmol/L (17 mg/dl) difference i s associated with 0.026 mm difference in carotid IMT in whites and 0.011 mm difference in African Americans. The associations are much weaker in Afric an Americans than whites at the bifurcation and internal carotid, the carot id sites most prone to atherosclerosis. Analysis was done stratifying for r isk factors that differ between African Americans and whites, but within mo st, the relationships remained substantially weaker in African Americans. CONCLUSIONS: We have observed a statistically significant difference in the association between many lipids/lipoproteins and carotid IMT between Afric an Americans and whites. Analysis of many potential cofactors have not prov ided an explanation for the weaker association. Although possible differenc es in prior levels of these lipids may provide one explanation for the find ing, these results need confirmation in other studies. Ann Epidemiol 1999;9 :149-158. Published by Elsevier Science Inc.