Abstract P276: Differential Association of D-dimer with Stroke and Coronary Heart Disease: The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Abstract

Introduction: D-dimer, a marker of coagulation activation, has higher levels in blacks than whites and has been variably associated with stroke and coronary heart disease (CHD). Methods: REGARDS recruited 30,239 participants in their homes across the continental US between 2003-07; by design 55% were female, 41% black, and 56% lived in the southeast. In a case-cohort study, D-dimer was measured in 646 participants with incident stroke, 515 with incident CHD, and 1104 in a cohort random sample. D-dimer was log transformed and modeled per 1-unit increase. Cox models were used to determine the HR for vascular disease for D-dimer and the difference in HR (95% CI) by race and vascular disease calculated by bootstrapping with 1000 replicate samples and using the 2.5 and 97.5 percentiles of the distribution (see Table for model variables). Results: Median D-dimer was higher in blacks (0.45 mcg/mL; IQR 0.26, 0.85) than whites (0.38 mcg/mL; IQR 0.23, 0.69); p <0.001. D-dimer was higher with increasing age, female gender, diabetes, hypertension and prebaseline cardiovascular disease (all p <0.05). The table shows the HR of stroke and CHD by baseline D-dimer. In minimally-adjusted models, D-dimer was associated with both stroke and CHD. Accounting for Framingham stroke and CHD risk factors, D-dimer remained associated with CHD (HR 1.45; 95% CI 1.18, 1.79), but was marginally associated with stroke (HR 1.20; 95% CI 0.99, 1.45). The difference in the HR of D-dimer between CHD and stroke was 0.22 in the basic model and 0.25 in the Framingham model, but this difference was of marginal statistical significance (Table). There was no difference in the HRs for stroke or CHD for D-dimer in blacks compared to whites (Table). Discussion: The association of D-dimer with stroke appeared smaller than for CHD with similar associations by race. Findings suggest that hemostasis activation may play a greater role in pathogenesis of CHD than stroke. Further study is needed to confirm these findings and evaluate the association of D-dimer with different stroke subtypes.