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 patients with nonvalvular AF initiating anticoagulation from October 2010 to December 2012 from a large US database of commercial and Medicare supplement claims. Multivariable regression examined associations between ischemic stroke (CHA2DS2-VASc) and bleeding (Anticoagulation and Risk Factors in Atrial Fibrillation [ATRIA]) risk scores and benefits' generosity (proportion of costs covered by patients relative to total) with warfarin and novel oral anticoagulant (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 an NOAC with high ischemic stroke risk (CHA2DS2-VASc ≥2; adjusted relative risk [aRR] 0.75, 95% confidence interval [CI] 0.72 to 0.77) and high bleeding risk (ATRIA ≥5; aRR 0.66, 95% CI 0.64 to 0.69) but more likely with good benefits' generosity (≤20% of costs borne by patient; aRR 2.03, 95% CI 1.92 to 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 to 1.24). In conclusion, patients with greater bleeding and ischemic stroke risk were more likely to initiate warfarin, but generous benefits more strongly predicted NOAC usage and drove more selection.
Bibliographical noteFunding Information:
The database infrastructure used for this project was funded by the Department of Epidemiology, UNC Gillings School of Global Public Health; the Cecil G. Sheps Center for Health Services Research, UNC; the CER Strategic Initiative of UNC’s Clinical Translational Science Aware (1 UL RR025747); and the UNC School of Medicine.
At the time of the research, Dr. Lauffenburger received T32NR008856 funding from the National Institute of Nursing Research . Drs. Rhoney, Fang, Gehi, and Lauffenburger have nothing relevant to declare. Dr. Brookhart has received research support from Amgen for unrelated projects; has served as a scientific advisor for Amgen, Merck, and GlaxoSmithKline (honoraria paid to institution); and received consulting fees from RxAnte and WHIC. Dr. Farley has received consulting support for unrelated projects from Daiichi-Sankyo.
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