Appropriateness of Direct Oral Anticoagulant Dosing in Patients With Atrial Fibrillation: Insights From the Veterans Health Administration

Abstract

Background: Direct oral anticoagulants (DOACs) have strict dosing guidelines, but recent studies indicate that inappropriate dosing is common, particularly in chronic kidney disease (CKD), for which it has been reported to be as high as 43%. Since 2011, the Veterans Health Administration (VA) has implemented anticoagulation management programs for DOACs, generally led by pharmacists, which has previously been shown to improve medication adherence. Objective: We investigated the prevalence of overdosing and underdosing of DOACs in the VA. Methods: Using data from the TREAT-AF cohort study (The Retrospective Evaluation and Assessment of Therapies in AF), we identified VA patients with newly diagnosed atrial fibrillation (AF) and receipt of a DOAC between 2003 and 2015. We classified dosing as correct, overdosed, or underdosed based on the Food and Drug Administration–approved dosing criteria. Results: Of 230 762 patients, 5060 received dabigatran (77.3%) or rivaroxaban (22.7%) within 90 days of AF diagnosis (age 69 [10[ years; CHA2DS2-VASc 1.6 [1.4]), of which 1312 (25.9%) had CKD based on estimated glomerular filtration rate <60. Overall, 93.6% of patients, 83.2% with CKD, received appropriate DOAC dosing. Incorrect dosing increased with worsening renal function. Conclusion: Compared to recent studies of commercial payers and health-care systems, incorrect dosing of DOACs is less common across the VA. Pharmacist-led DOAC management or similar anticoagulation management interventions may reduce the risk of incorrect dosing across health-care systems.