Variation in the Use of Warfarin and Direct Oral Anticoagulants in Atrial Fibrillation and Associated Cost Implications

Background: Little is known about national patterns of anticoagulant use among patients with atrial fibrillation after the availability of direct oral anticoagulants (DOACs) and the associated implications for healthcare spending. Methods: The Medical Expenditure Panel Survey, a nationally representative survey, collects detailed information about prescription drug use, cost, and medical diagnoses. Using International Classification of Disease Ninth Edition (ICD-9) codes and self-reporting, adults with atrial fibrillation were estimated between 2010 and 2014. We examined proportions of patients receiving warfarin and DOACs overall and across sociodemographic and clinical groups. Total drug expenditures and out-of-pocket spending were calculated adjusting to 2014 US dollars. Results: The study population ranged from 364 (equivalent to 4.7 million) in 2010 to 409 (equivalent to 5.5 million) in 2014. Overall use of any anticoagulant increased from 32.4% to 40.1%. DOAC use increased from 0.56% to 17.2%, and warfarin use declined from 32.8% to 22.9% (p trend < 0.01). This trend was seen in nearly all subgroups evaluated. Estimated prescription drug spending on DOACs and warfarin during this time rose from $330 million to $1.9 billion. Out-of-pocket costs for DOACs increased from $10 million to $218 million. Conclusion: In a large, nationwide cohort of adults with atrial fibrillation, we observed a rapid increase in the use of DOACs, significant disparities in medication use based on sociodemographic and clinical factors, and an increase in overall and out-of-pocket costs for anticoagulants corresponding to the increased use of DOACs. These patterns have important implications for healthcare quality, equity, and spending.