Abstract 20418: Racial Differences in Outcomes With Dabigatran and Rivaroxaban versus Warfarin in Medicare Population With Atrial Fibrillation
Introduction: Dabigatran and rivaroxaban were approved for stroke prevention in atrial fibrillation (AF) based on clinical trials which included very few black patients.
Hypothesis: To assess if dabigatran and rivaroxaban have similar outcomes versus warfarin in black compared to white patients with AF.
Methods: Black and white patients age 66 and older with new AF from November 2010 to December 2013 who initiated dabigatran 150 mg, rivaroxaban 20 mg, or warfarin within 90 days of AF diagnosis were identified using the Medicare claims. Patient characteristics were determined using claims incurred during the prior 12 months. Outcomes of death, stroke, gastrointestinal bleeding and intracranial hemorrhage were investigated in analyses that incorporated three-way propensity matching by drug within race, with additional risk adjustment using Cox proportional hazard models.
Results: Overall, 138,273 white patients and 7,440 black patients met inclusion criteria. In propensity matched samples, dabigatran and rivaroxaban were associated with lower hazard of death (relative to warfarin) for whites [Hazard ratio (HR)=0.82; p=0.01 and HR=0.77; p=0.001 respectively] as well as blacks [HR=0.32; p=0.12 and HR=0.36; p=0.005 respectively]. The risk of stroke did not differ significantly by drug within white or black patients, although we note that hazard ratios trended in the opposite direction for black and white patients. The hazard of gastrointestinal hemorrhage was higher for white patients taking rivaroxaban vs warfarin [HR=1.06; p=0.50 and HR=1.33; p=.0003 respectively], but not for dabigatran. A similar, but not statistically significant, increase in gastrointestinal hemorrhage with rivaroxaban was seen in black patients. Whites on dabigatran or rivaroxaban had lower risk of intracranial hemorrhage compared to warfarin [HR 0.47; p=0.01 and 0.74; p=0.23 respectively]. There were only 3 intracranial hemorrhages noted in the blacks.
Conclusions: In an elderly Medicare population with newly diagnosed AF, compared to warfarin, dabigatran and rivaroxaban were associated with a lower risk of death in both whites and blacks. We found no evidence that relative outcomes of dabigatran or rivaroxaban relative to warfarin differ in white and black patients.
Author Disclosures: R. Kabra: None. M. Vaughan Sarrazin: None.
- © 2016 by American Heart Association, Inc.