Practice-Level Variation in Warfarin Use Among Outpatients With Atrial Fibrillation (From the NCDR PINNACLE Program)

Study Questions:

How often is warfarin underutilized in patients with atrial fibrillation (AF) at moderate to high risk of stroke?


Data on 9,113 patients (mean age 76 years) with AF and a CHADS2 score >1 were extracted from a national prospective office-based quality improvement registry (PINNACLE). The primary outcome was the rate of warfarin therapy in these patients.


Fifty-five percent of the patients with a CHADS2 score >1 were treated with warfarin. There were no significant differences in mean CHADS2 score, age, comorbidities, or rate of prior stroke between the patients who did and did not receive warfarin. There was no relationship between the CHADS2 score and treatment with warfarin. Among the patients not receiving warfarin, 51% were treated with aspirin, 4% with a thienopyridine, and 10% with aspirin plus a thienopyridine. The rate of warfarin usage ranged from 25-80% among the 20 practices that participated in the registry.


Almost 50% of outpatients with AF who have a CHADS2 score >1 and are at moderate to high risk of stroke are not treated with warfarin.


This study confirms the results of prior studies that have demonstrated widespread underutilization of warfarin in AF patients with risk factor profiles that justify the use of warfarin. Although the specific reasons for underutilization were not documented in this or prior studies, it is likely that the inconveniences and risk of hemorrhagic complications associated with warfarin are major factors. It is possible that dabigatran, which is not associated with many of the inconveniences of warfarin, will improve the utilization of oral anticoagulant therapy, but this remains to be seen.

Clinical Topics: Anticoagulation Management, Novel Agents

Keywords: Stroke, Warfarin, Comorbidity, Pyridines, Risk Factors, Registries, beta-Alanine, Outpatients, Benzimidazoles

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