Association of Race/Ethnicity with Oral Anticoagulant Use in Patients with Atrial Fibrillation

Kristine Conrow, Pharm.D., Walgreens/UMP Bethesda Clinic

Background: The updated 2018 CHEST guidelines for antithrombotic therapy for atrial fibrillation (AF) by the American College of Chest Physicians (ACCP) recommend direct-acting oral anticoagulants (DOACs) over warfarin in patients with AF. The cost of DOACs may be a barrier for patients, leading to the use of warfarin. It is unknown if racial and ethnic differences are associated with differences in the use of oral anticoagulants (OACs), including DOACs, after controlling for clinical and socioeconomic factors. Racial differences have been noted in prevalence and outcomes of AF. There’s a lower prevalence of AF in African Americans and Hispanics, yet these populations experience a higher risk of stroke and worse outcomes compared to Caucasians.

Objective: To determine if there are any racial/ethnic differences among patients taking an OAC for the treatment of AF.

Study Design: The US-based Outcomes Registry for Better Informed Treatment of Atrial Fibrillation II (ORBIT-AF II), a prospective registry from February 2013 to July 2016 of outpatient patients 21 years and older with AF, was utilized to create this cohort study. Data from ORBIT-AF II was analyzed to include 12,417 patients with AF in this study – 11,100 (89.4%) Caucasians, 646 (5.2%) African Americans, and 671 (5.4%) Hispanics. The participants were followed at 6-month intervals for 1 to 2 years depending on their enrollment date. Use of any OAC, with a focus on DOACs, was the primary outcome of the study.  Secondary outcomes were quality of anticoagulation therapy received by the participants and OAC discontinuation rates after one year.

Results: Compared to Caucasian patients, Hispanic and African Americans patients were more likely to have Medicaid insurance (Caucasian 2.9%, Hispanic 15.5%, African American 11.6%, P<0.001) and less likely to have a college degree (Caucasian 29.6%, Hispanic 17.2%, African American 17.2%, P<0.001). After baseline clinical features were adjusted (i.e. demographics, medical history, medications, laboratory data, AF status, and enrolling physician specialty), African Americans were less likely to receive any OAC compared to Caucasians (adjusted odds ratio [aOR], 0.75 [95% CI 0.56-0.99], P=0.04). If on an OAC, African Americans were also less likely to be prescribed a DOAC compared to Caucasians (aOR, 0.63 [95% CI 0.49-0.83], P<0.001). When baseline socioeconomic markers were adjusted (i.e. median household income, level of education, and insurance type), a significant difference in DOAC prescribing remained between African Americans and Caucasians (aOR, 0.73 [95% CI 0.55-0.95], P=0.02). No significant difference was seen between Hispanic and Caucasian patients in receiving OACs or prescribing of a DOAC when adjustments were made for baseline clinical features and socioeconomic markers. Analysis of the quality of OAC use showed the median time of warfarin users in therapeutic range compared to Caucasians was less in African American and Hispanic patients (P<0.001).  Additionally, patients prescribed DOACs were dosed inappropriately (under-dosed or excessively dosed) more often in non-Caucasian patients (African American 15.5%, Hispanic 18.1%, Caucasian 12.6%, P=0.01). No significant difference was seen in discontinuation rates of OAC after one year.

Conclusions: Caucasian patients were more likely to receive a DOAC to treat AF compared to African American patients, even when clinical features and socioeconomic factors were adjusted. When prescribed DOACs, they were significantly more likely to be on an inappropriate dose of a DOAC.
Additionally, when compared to Caucasians, Hispanic and African American patients taking warfarin were less often in therapeutic range. These differences among racial and ethnic groups in the use of OACs and DOACs may contribute to worse outcomes in African American and Hispanic populations.

Key Point: Reducing disparities in the provision of anticoagulation in patients with AF may improve outcomes in this patient population.

References:

  1. Essien UR, Holmes DN, Jackson LR, et al. Association of race/ethnicity with oral anticoagulant use in patients with atrial fibrillation. JAMA Cardiol 2018;3(12):1174-1182.

  2. Lip GYH, Banerjee A, Boriani G, et al. Antithrombotic therapy for atrial fibrillation: CHEST guideline and expert panel report.CHEST 2018; 154(5):1121-1201.