National Trends in Oral Anticoagulant Use in the United States, 2007 to 2011
What are the patterns of oral anticoagulant use in the United States between 2007 and 2011, specifically pertaining to warfarin and dabigatran use in atrial fibrillation?
The authors used data from the national disease and therapeutic index (NDTI), an ongoing physician survey based on an audit of roughly 4,800 physicians, randomly selected from the American Medical Association and American Osteopathic Association master files. Surveyed physicians were asked to provide data on all patients seen in two consecutive days per quarter. The authors quantified patterns of oral anticoagulant use among all subjects stratified by clinical indication and type of anticoagulant. They also quantified expenditures for anticoagulants using the National Prescription Audit. Both surveys are performed by IMS Health (Collegeville, PA).
Between 2007 and 2011, treatment visits associated with warfarin use declined from roughly 2.1 million quarterly visits to roughly 1.6 million. Dabigatran use increased from 0.062 million quarterly visits (Q4; 2010) to 0.363 million visits (Q4; 2011). This corresponded to an increase in the share of oral anticoagulation visits associated with dabigatran from 3.1% to 18.9%. The fraction of office visits with the diagnosis of atrial fibrillation not treated with any oral anticoagulant remained unchanged at roughly 40%. Warfarin use among atrial fibrillation visits decreased from 55.8% of visits (Q4; 2010) to 44.4% (Q4; 2011), during which time dabigatran use increased from 4.0% to 16.9%. Expenditures related to dabigatran increased more rapidly from $16 million (Q4; 2010) to $166 million (Q4; 2011), by which time they exceeded expenditures on warfarin ($144 million).
The authors concluded that dabigatran has been rapidly adopted into ambulatory practice in the United States, primarily for treatment of atrial fibrillation, but increasingly for off-label indications. The authors observed that they did not find evidence that it has increased overall atrial fibrillation treatment rates.
These data, derived from physician surveys reporting information from random patient encounters, suggest that within a year of Food and Drug Administration approval for dabigatran, almost 20% of office visits associated with anticoagulant use were associated with dabigatran. It is also impressive that by that time, almost one third of the dabigatran usage was associated with diagnoses other than atrial fibrillation. The implications of this rapid adoption remain to be seen. Clinical trials of dabigatran for both venous thromboembolism and atrial fibrillation demonstrated equal or superior efficacy and safety. Outside of clinical trials, the lack of a readily available test of dabigatran effect, the lack of any known reversal agent, and the effect of nonadherence may present novel challenges.
Keywords: Blood Coagulation, United States Food and Drug Administration, Benzimidazoles, Cardiology, Warfarin, Venous Thromboembolism, United States
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