Assessment of Racial Variation in Risk of Coronary Heart Disease and Stroke Mortality for Elevated Levels of Systolic Blood Pressure

Purpose Elevated blood pressure, primarily systolic blood pressure (SBP), is widely recognized as a major independent risk factor for cardiovascular disease (CVD). The purpose of this study is to determine if CVD risk associated with elevated SBP varies for blacks and whites. Methods Data from the Black Pooling Project, which includes individual data from four observational studies with a sample size of 26,083, was utilized. Cox proportional hazard models (controlling for study, age, and gender) were performed to obtain hazard ratios of stroke and coronary heart disease (CHD) mortality at 10 mmHg unit increments of SBP with referent group SBP<120mmHg. A race-by-SBP level interaction parameter was calculated to detect significant racial variation in risk and race-specific models were run to obtain estimates for blacks and whites separately. Additional models were performed adjusting for other CVD risk factors: body mass index, diabetes, total cholesterol level, and smoking status. Results During a maximum 30 years of follow-up, there were 302 and 631 stroke deaths and 569 and 2388 CHD deaths for blacks and whites respectively. The hazard ratios of stroke mortality for blacks and whites exhibit a step-wise increase for each additional 10 unit increase in SBP. The hazard ratios and 95% confidence intervals at SBP level≥180 are 3.96 (2.0–8.0) and 3.71 (2.6–5.3) for blacks and whites respectively. Results for CHD mortality show a similar increase in risk with greater SBP levels. The CHD mortality hazard ratios and 95% confidence intervals at SBP level≥ 180 for blacks and whites were 2.65 (1.8–3.9) and 3.24 (2.7–3.9) respectively. Conclusion In conclusions, elevated risk of stroke and CHD mortality are seen with respect to increasing SBP levels in both blacks and whites. There was no statistically significant interactions involving race and SBP level thus the risk associated is similar for blacks and whites.