Explaining racial disparities in anticoagulation control: results from a study of patients at the Veterans Administration.

Higher rates of stroke, major hemorrhage, and death among black patients receiving warfarin, compared with white patients, is likely related to poorer anticoagulation control. The research team investigated patient-level and site-level factors that might account for this group difference. A summary measure of anticoagulation control (percent time in therapeutic range [TTR]), patient characteristics, and site-level process of care measures were obtained for 9572 black and 88 481 white patients at the Veterans Health Administration. The research team studied disparity in TTR adjusting for patient and site characteristics. Mean unadjusted TTR for black patients was 6.5% lower than for white patients (P<.001). After accounting for the younger age of blacks, greater degrees of medication use, hospitalization, poverty, living in the South, and 11 other patient characteristics, only 2.0% of this racial disparity persisted. Process of care measures had minimal additional effect. These findings may inform efforts to reduce this racial disparity in achieving good anticoagulation control.