Abstract P004: Association of C-Reactive Protein with Incident Coronary Events in Blacks and Whites: The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Abstract

Background: Elevated C-reactive protein (CRP) is associated with coronary heart disease (CHD) risk independent of traditional CHD risk factors. Few studies include many non-white participants despite known racial differences in CRP. We assessed whether there were racial differences in the association between CRP and incident CHD in a large cohort of AA and white Americans. Methods: 30,239 AAs and whites were enrolled and examined in their homes across the US from 2003-07. CHD, defined as myocardial infarction or acute CHD death, was captured by participant report and physician medical record review. We used Cox models in those free of CHD at baseline to assess the association of CRP with incident CHD. Results: Over a median 3.7 years follow-up (maximum 5.9 years), 505 CHD events occurred in 24,297 individuals without baseline CHD (223 in 10,337 AA). AA had higher levels of many traditional CHD risk factors, including hypertension (69% vs 47%), diabetes (28% vs 13%), current smoking (17% vs 12%, all <0.01), but higher high-density lipoprotein cholesterol (54 vs 52 mg/dL, p<0.01) and similar total cholesterol (195 vs 192 mg/dL, p=0.16). Median CRP was higher in AA than whites (2.85 vs 1.82 mg/L, p<0.01), with 4,615/9,558 (48%) of blacks vs. 4,548/13,217 (34%) of whites having a CRP ≥3 mg/L (p<0.01) . The table presents the HR of CHD for CRP ≥3 mg/L and per 1 unit increase in log CRP stratified by race. AA did not have a higher hazard of CHD than whites in any model (data not shown). Discussion: Despite higher levels of CRP in AA, CRP was not differentially associated with CHD between AA and whites. Though the HR for CRP ≥3 mg/L appeared weaker in AA vs. whites this was not supported by a significant p-interaction. The paradox of an adverse CHD risk factor profile but similar risk of CHD was not explained by differential associations of CRP with CHD in AA vs. whites. Further analyses of fatal and non-fatal MI as well as the performance of traditional and non traditional CHD risk factors in AA vs. whites are warranted. Table Association of CRP with Incident CHD in African-Americans and Whites All HR (95% CI) Blacks HR (95% CI) Whites HR (95% CI) P-interaction between race and CRP CRP ≥3 mg/L Model 1 1.63 (1.35, 1.96) 1.46 (1.11, 1.93) 1.75 (1.37, 2.24) 0.57 Model 2 1.37 (1.14, 1.66) 1.26 (0.95, 1.67) 1.46 (1.13, 1.88) 0.52 Model 3 1.33 (1.10, 1.61) 1.20 (0.90, 1.61) 1.41 (1.10, 1.82) 0.58 Per 1 unit increase in log CRP Model 1 1.32 (1.22, 1.43) 1.29 (1.15, 1.45) 1.34 (1.20, 1.49) 0.95 Model 2 1.23 (1.13, 1.33) 1.23 (1.09, 1.39) 1.22 (1.09, 1.36) 0.81 Model 3 1.21 (1.12, 1.31) 1.21 (1.07, 1.37) 1.20 (1.07, 1.34) 0.73 Model 1: Age, Sex, and Region Model 2: Model 1 + Hypertension, Diabetes, Smoking, Total Cholesterol, HDL Cholesterol, Taking Dyslipidemia Meds Model 3: Model 2 + Income, Education