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Trends in antithrombotic therapy for atrial fibrillation: Data from the Veterans Health Administration Health System
Joshua Buck1, Peter Kaboli2, Brian F Gage3
1Comprehensive Access and Delivery Research and Evaluation Center (CADRE), Iowa City VA Medical Center, Iowa City, IA.
Insights
Oral anticoagulant (OAC) use in atrial fibrillation (AF) patients declined from 2002 to 2011. Despite stroke risks, OAC prescription rates decreased across all CHADS2 scores, indicating underuse in this veteran population.
Area of Science:
- Cardiology
- Pharmacology
- Public Health
Background:
- Atrial fibrillation (AF) affects over 2 million Americans, increasing stroke risk.
- Oral anticoagulants (OACs) are crucial for reducing stroke risk in moderate-to-high risk AF patients.
- Previous studies suggest OACs are underused in the US AF population.
Purpose of the Study:
- To quantify trends in OAC use over a 10-year period in US veterans with new-onset AF.
- To evaluate adherence to OAC guidelines based on stroke risk stratification.
- To assess the proportion of AF patients receiving OACs at diagnosis.
Main Methods:
- Retrospective analysis of 297,611 US veterans diagnosed with new AF between 2002 and 2011.
- CHADS2 scores calculated using patient demographics and diagnoses (Congestive Heart Failure, Hypertension, Age > 75, Diabetes, Stroke).
- OAC (warfarin or dabigatran) receipt within 90 days of AF diagnosis determined via VA pharmacy data.
Main Results:
- OAC initiation decreased from 51.3% in 2002 to 43.1% in 2011.
- Prescription rates declined across all CHADS2 score categories, with relative decreases ranging from 9% to 26%.
- Clopidogrel use remained stable at 10% in the AF population.
Conclusions:
- Approximately half of US veterans with new AF and stroke risk factors receive OACs.
- The proportion of AF patients initiated on OACs has declined over the study period.
- Underuse of OACs persists in the veteran AF population, despite established stroke reduction benefits.
Background:
Although controversial, several prior studies have suggested that oral anticoagulants (OACs) are underused in the US atrial fibrillation (AF) population. Appropriate use of OACs is essential because they significantly reduce the risk of stroke in those with AF. In the >2 million Americans with AF, OACs are recommended when the risk of stroke is moderate or high but not when the risk of stroke is low. To quantify trends and guideline adherence, we evaluated OAC use (either warfarin or dabigatran) in a 10-year period in patients with new AF in the Veterans Health Administration.
Methods:
New AF was defined as at least 2 clinical encounters documenting AF within 120 days of each other and no previous AF diagnosis (N = 297,611). Congestive Heart Failure, Hypertension, Age > 75, Diabetes, and Stroke (CHADS2) scores were determined using age and diagnoses of hypertension, diabetes, heart failure, and stroke or transient ischemic attack during the 12 months before AF diagnosis. Receipt of an OAC within 90 days of a new diagnosis of AF was evaluated using VA pharmacy data.
Results:
Overall, initiation of an OAC fell from 51.3% in 2002 to 43.1% in 2011. For patients with CHADS2 score of 0, 1, 2, 3, 4, and 5-6, the proportions of patients prescribed an OAC showed a relative decrease of 26%, 23%, 14%, 12%, 9%, and 13%, respectively (P < .001). Clopidogrel use was stable at 10% of the AF population.
Conclusions:
Among US veterans with new AF and additional risk factors for stroke, only about half receive OAC, and the proportion is declining.
