Abstract 19410: Stroke and CHADS2 Score Do Not Predict Warfarin Use Nationally in Atrial Fibrillation
Background: Atrial fibrillation (AF) carries a significant stroke risk, which is commonly estimated by the CHADS2 scoring system. While multiple centers have reported under-utilization of warfarin for high risk patients with atrial fibrillation, national utilization patterns among high risk patients have not been well described.
Hypothesis: A history of stroke and/or CHADS2 score of 2-6 would be associated with warfarin use in AF patient visits.
Methods: We used two databases (National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey) to estimate the annual number of outpatient clinic visits nationally from 2005-2007 for patients with AF and to quantify the medications they are taking. Binomial multivariate logistic regression analysis was performed for aspirin (ASA) and warfarin use while controlling for CHADS2 scoring, year of clinic visit, sex, race, physician specialty, and patient age. A separate logistic regression model was created including a history of heart failure, hypertension, diabetes and stroke in place of the combined CHADS2 score.
Results: Among 23 million office visits from 2005-2007, CHADS2 score does not correlate with warfarin use (OR 1.309, 95% CI 0.889-1.927). A history of stroke does not correlate with warfarin use (OR 1.312, 95% CI 0.833-2.066). Patients seen in the south (OR 0.456, 95% CI 0.281-0.741) and west (OR 0.382, 95% CI 0.222-0.658) are less likely to use warfarin than patients in the northeast. Cardiologists have a trend towards increased warfarin use (OR 1.368, 95% CI 0.969-1.933) compared to primary providers.
Conclusion: Despite evidence that atrial fibrillation patients with a history of stroke or CHADS2 score of 2-6 are at increased risk of systemic thromboembolism, neither factor correlates with warfarin use nationally. Physicians in the northeast prescribe warfarin more often than providers in the south or west. There was no increased rate of warfarin therapy over the 3 year study period.
- © 2010 by American Heart Association, Inc.