Abstract P217: Coagulation Factor IX Levels and Risk of Stroke and Coronary Heart Disease: The REasons for Geographic And Racial Differences in Stroke Study (REGARDS)

Introduction: The role of coagulation in coronary heart disease (CHD) and stroke remains controversial. We examined the association of levels of coagulation factor IX (FIX) with incident CHD and ischemic stroke in REGARDS. Methods: REGARDS recruited 30,239 participants in their homes across the contiguous U.S. between 2003-07; by design 41% were black, 55% female, and 56% lived in the southeast. Levels of FIX were measured in participants with incident CHD (n=654), incident stroke (n=646), and in a cohort random sample (n=1,104). Cox models were used to calculate the hazard ratio (HR) per standard deviation (SD) higher FIX level for incident CHD and stroke adjusting for traditional cardiovascular disease (CVD) risk factors, and testing a race by FIX interaction term. Participants with hemorrhagic stroke were excluded from the stroke analyses (n=73). Results: Levels of FIX were higher with increasing age, black race, female gender, diabetes, hypertension, dyslipidemia, and among those living in the southeastern U.S. (all p<0.0001). As shown in the table, FIX levels (per 1 SD higher) were associated with CHD, but not stroke, after adjustment for CVD risk factors. When stratified by race, the association with CHD was stronger in blacks than whites (p-interaction = 0.08) with no association for stroke in either blacks or whites (p-interaction 0.71). Analyses of FIX by quintiles did not alter the results. Discussion: Levels of coagulation factor IX were significantly associated with incident CHD, but not stroke in blacks but not whites, after adjustment for CVD risk factors. These data suggest that higher levels of FIX are a risk factor for CHD in blacks but not whites, and may indicate different roles for hemostasis in vascular disease risk by race and by vascular disease type.