Race/Ethnicity and Sex-Related Differences in Direct Oral Anticoagulant Initiation in Newly Diagnosed Atrial Fibrillation: A Retrospective Study of Medicare Data.

backgroundAtrial fibrillation (AF) is the most common heart rhythm disorder and is associated with a 5-fold increased risk of ischemic stroke. Racial/ethnic minorities and women with AF have higher rates of stroke compared to white individuals and men respectively. Oral anticoagulation reduces the risk of stroke, yet prior research has described racial/ethnic and sex-based variation in its use. We sought to examine the initiation of any oral anticoagulant (warfarin or direct-acting oral anticoagulants, DOACs) by race/ethnicity and sex in patients with incident, non-valvular AF. Further in those who initiated any anticoagulant, we examined DOAC vs. warfarin initiation by race/ethnicity and sex.

methodsWe used claims data from a 5% sample of Medicare beneficiaries to identify patients with incident AF from 2012 to 2014, excluding those without continuous Medicare enrollment. We used logistic regression to assess the association between race/ethnicity (white, black, Hispanic), sex, and oral anticoagulant initiation (any, warfarin vs. DOAC), adjusting for sociodemographics, medical comorbidities, stroke and bleeding risk.

resultsThe cohort of 42,952 patients with AF included 17,935 women, 3282 blacks, and 1958 Hispanics. Overall OAC initiation was low (49.2% whites, 48.1% blacks, 47.5% Hispanics, 48.1% men, and 51.5% women). After adjusting, blacks (odds ratio (OR) 0.84; 95% CI, 0.78-0.91) were less likely than whites to initiate any oral anticoagulant with no difference observed between Hispanics and whites (OR 0.92; 95% CI, 0.83-1.01). Women were less likely than men to initiate any oral anticoagulant, OR 0.59 (95% CI 0.55-0.64). Among initiators of oral anticoagulation, DOAC use was low (35.8% whites, 29.3% blacks, 40.0% Hispanics, 41.6% men, and 42.4% women). After adjusting, blacks were less likely to initiate DOACs than whites, OR 0.75 (95% CI 0.66-0.85); the odds of DOAC initiation did not differ between Hispanic and white patients or between men and women.

conclusionIn a national cohort of Medicare beneficiaries with newly-diagnosed AF, overall oral anticoagulant initiation was lower in blacks and women, with no difference observed by Hispanic ethnicity. Among oral anticoagulant initiators, blacks were less likely to initiate novel DOACs, with no differences identified by Hispanic ethnicity or sex. Identifying modifiable causes of treatment disparities is needed to improve quality of care for all patients with AF.