D-dimer and the Risk of Incident Hypertension in Black and White Americans

The underlying causes of hypertension remain ill-defined as are the reasons for the increased risk among black Americans. Research suggests D-dimer, a procoagulant marker higher in black Americans, is a risk marker for hypertension. However, these data are mostly cross-sectional, and the impact on racial disparities in hypertension incidence has not been studied. We hypothesized that those with higher D-dimer levels will be at a higher risk of developing incident hypertension, and D-dimer modifies racial differences in hypertension risk. The study included 1438 participants, without hypertension at baseline, with two visits 9.4 years apart in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. Risk ratios of incident hypertension by baseline D-dimer were estimated, and the DDimer*race interaction was assessed. Factors associated with higher D-dimer were older age, female sex, black race, smoking, higher BMI and systolic blood pressure, and lower education, income and physical activity. A modest association was observed between D-dimer and hypertension incidence; in the model adjusted for demographic factors, the risk of hypertension was 32% higher in the top quartile of D-dimer compared to the first quartile [risk ratio (RR) 1.32; 95% confidence interval (CI):1.07-1.63]. However, this association was not independent of other risk factors (RR 1.18; 95% CI 0.97-1.45). There was no evidence D-dimer modified the racial difference in hypertension risk (p-interaction >0.10). Results suggest that procoagulant effects of hypertension risk factors may contribute to hypertension risk. While D-dimer increased the risk of hypertension, it did not modify the racial difference in hypertension risk. Future research will examine whether D-dimer mediates racial disparities in hypertension risk.