Racial and Regional Differences in Venous Thromboembolism in the United States in Three Cohorts
Background—Blacks are thought to have a higher risk of venous thromboembolism (VTE) than whites however prior studies are limited to administrative databases that lack specific information on VTE risk factors or have limited geographic scope.
Methods and Results—We ascertained VTE from three prospective studies; the Atherosclerosis Risk in Communities study (ARIC), the Cardiovascular Health Study (CHS), and the REasons for Geographic and Racial Differences in Stroke study (REGARDS). We tested the association of race with VTE using Cox proportional hazard models adjusted for VTE risk factors. Over 438,090 person-years, 916 incident VTE events (302 in blacks) occurred in 51,149 individuals (17,318 blacks) followed. In risk factor-adjusted models, blacks had a higher rate of VTE than whites in CHS (HR 1.81; 95% CI 1.20, 2.73) but not ARIC (HR 1.21; 95% CI 0.96, 1.54). In REGARDS, there was a significant region by race interaction (p = 0.01); blacks in the southeast had a significantly higher rate of VTE than blacks in the rest of the US (HR 1.63; 95% CI 1.08, 2.48) which was not seen in whites (HR 0.83; 95% CI 0.61, 1.14).
Conclusions—The association of race with VTE differed in each cohort, which may reflect the different time periods of the studies and/or different regional rates of VTE. Further study of environmental and genetic risk factors for VTE are needed to determine which underlie racial and perhaps regional differences in VTE.
- Received September 24, 2013.
- Revision received January 2, 2014.
- Accepted January 13, 2014.