Factors Driving Anticoagulant Selection in Patients With Atrial Fibrillation in the United States

Abstract

With the introduction of novel oral anticoagulants (NOACs), the factors driving anticoagulant selection in atrial fibrillation (AF) in real-world practice are unclear. The goal was to examine whether and to what extent utilization has been driven by predictions of stroke risk (treatment benefit), bleeding risk (treatment harm), or prescription benefits’ coverage. We extracted a cohort of non-valvular AF patients initiating anticoagulation from Oct 2010-Dec 2012 from a large US database of commercial and Medicare supplement claims. Multivariable regression examined associations between ischemic stroke (CHA2DS2-VASc) and bleeding (ATRIA) risk scores and benefits’ generosity (proportion of costs covered by patients relative to total) with warfarin and NOAC selection and also between dabigatran and rivaroxaban. C-statistics and partial chi-square statistics were used to assess the variation explained. Of 70,498 patients initiating anticoagulation, 29.9% and 7.9% used dabigatran and rivaroxaban, respectively. Compared with warfarin, patients were less likely to receive a NOAC with high ischemic stroke risk (CHA2DS2-VASc ≥2) (Adjusted Relative Risk [aRR]: 0.75, 95% CI: 0.72-0.77) and high bleeding risk (ATRIA≥5) (aRR: 0.66, 95% CI: 0.64-0.69) but more likely with good benefits’ generosity (≤20% of costs borne by patient) (aRR: 2.03, 95% CI: 1.92-2.16). Prescription generosity explained almost twice the model variation as either risk score. Compared with dabigatran, patients were more likely to fill rivaroxaban with high bleeding risk (aRR: 1.16, 95% CI: 1.09-1.24). In conclusion, patients with higher bleeding and ischemic stroke risk were more likely to initiate warfarin, but generous benefits more strongly predicted NOAC usage and drove more selection.

Risk of intraocular hemorrhage with new oral anticoagulants

“…Warfarin inhibits vitamin K utilization, which reduces the activation of prothrombin complex proteins and the activity of clotting factors, effectively slowing thrombin generation and clot formation. [2][3][4] NOACs such as rivaroxaban and apixaban are specific inhibitors of factor Xa, and dabigatran is a direct thrombin inhibitor. [3][4][5] Reducing the risk of forming a clot increases hemorrhagic diathesis, [3][4][5] which increases the risk of intraocular hemorrhage.…”

“…1 The main advantage of NOACs compared with warfarin is the lack of coagulation monitoring or dosage adjustments required due to more predictable pharmacokinetic properties. [2][3][4] Recent studies have examined the risk of bleeding with these drugs, however, information on the risk of ocular bleeding with NOACs is scant.…”

Determinants and consequences of differences in quality of anticoagulation therapy with vitamin K antagonists

“…In a cohort from the United States (2010-2012), 62% of patients with non-valvular atrial fibrillation (AF) were prescribed warfarin [1], and data from Europe (2013) showed a range of DOAC use between 0.3% (Italy) and 11.6% (Germany) [2] in the same patient group.…”

Management of Anticoagulation Around Cardiac Implantable Electronic Device Surgery

“…The use of novel anticoagulants (NOACs) has increased dramatically since its introduction with about 1/3 of patients with AF using them for stroke prophylaxis [17]. They represent a safe and efficacious alternative to warfarin.…”