Oral Anticoagulant Therapy in Patients With Atrial Fibrillation

Study Questions:

What is the extent of oral anticoagulant (OAC) use in US cardiology practices based on the number of stroke risk factors for atrial fibrillation (AF) patients?


Using the National Cardiovascular Data Registry (NCDR) Practice Innovation and Clinical Excellence (PINNACLE) registry, a cross-sectional analysis of OAC and antiplatelet use among AF patients between 2008 and 2012 was performed. The CHADS2 and CHA2DS2-VASc stroke risk scores were calculated for each patient. Multinomial logistic regression analysis adjusted the association of stroke risk and OAC use based on patient, physician, and practice characteristics.


Of 429,417 outpatients with AF, 192,600 (44.9%) were prescribed an OAC, 111,134 (25.9%) were prescribed aspirin only, 23,454 (5.5%) were prescribed aspirin plus a thienopyridine, and 102,229 (23.8%) had no antithrombotic therapy prescribed. Each 1-point increase in the stroke risk score was associated with increased odds of OAC prescription as compared to aspirin only (adjusted odds ratio [OR], 1.158; 95% confidence interval [CI], 1.144-1.172; p < 0.001 for CHADS2; adjusted OR, 1.163; 95% CI, 1.157-1.169; p < 0.001). Overall use of OAC never exceeded 51% of any stroke risk group. Use of OAC varied greatly between practice sites, ranging from ~5% to ~90% (median, 51.7%; interquartile range, 37.7%-58.3%) in the cohort of practices participating in PINNACLE.


The authors concluded that in a large quality improvement registry of outpatient AF patients, use of OAC as compared to aspirin increased as stroke risk increased, but never exceeded 51% of any cohort.


This study uses high-quality, chart-abstracted data from a large multicenter cohort of outpatients with AF to highlight the issue of stroke-prevention undertreatment with OAC therapy. While patients at increased risk of stroke were more likely to receive OAC therapy as compared to aspirin therapy, overall use of OAC therapy never exceeded ~50% of the population. However, the study period pre-dates widespread use of direct OACs (e.g., dabigatran and rivaroxaban), which have been associated with an increased rate of overall OAC use in AF patients (Am J Med 2015;128:1300-1305). Still, further efforts are needed to improve the use of OAC therapy among AF patients, especially those at moderate and high risk of stroke.

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