Absolute and attributable risks of cardiovascular disease incidence in relation to optimal and borderline risk factors - Comparison of African American with white subjects - Atherosclerosis risk in communities study

Background: Among white Americans, a large proportion of cardiovascular disease (CVD) events is explained by borderline or any elevated CVD risk factor levels, The degree to which this is true among African American subjects is unclear. Methods: The Atherosclerosis Risk in Communities Study included 14 162 middle-aged adults who were free of recognized stroke or coronary heart disease and had baseline information on risk factors. Based on national guidelines, we categorized risk factors (blood pressure, cholesterol levels, diabetes, and smoking) into 3 categories, ie, optimal, borderline, and elevated. Incidence of CVD (composite of stroke and coronary heart disease) (n = 1492) and CVD mortality (n = 612) were identified for a 13-year period. Results: The proportion of subjects with all optimal risk factor levels was lower in African American (3.8%) than in white (7.5%) subjects. Conversely, the proportion of subjects with at least 1 elevated risk factor was higher in African American (approximately 80%) than in white (approximately 60%) subjects. After adjustment for these risk factor differences and education level, African American and white subjects had virtually identical rates of CVD (relative hazard for African American subjects, 1.01; 95% confidence interval, 0.90-1.14). The proportion of CVD events explained by elevated risk factors was high in African American subjects (approximately 90%) compared with approximately 65% in white subjects. Conclusions: The higher CVD incidence rate in African American than in white subjects seems largely attributable to a high frequency of elevated CVD risk factors in African American subjects. Primary prevention of elevated CVD risk factors in African American subjects might greatly reduce CVD occurrence as much as it has for white subjects.