Differences and trends in stroke prevention anticoagulation in primary care vs cardiology specialty management of new atrial fibrillation: The Retrospective Evaluation and Assessment of Therapies in AF (TREAT-AF) study

Background Atrial fibrillation and flutter (AF, collectively) cause stroke. We evaluated whether treating specialty influences warfarin prescription in patients with newly diagnosed AF. Methods In the TREAT-AF study, we used Veterans Health Administration health record and claims data to identify patients with newly diagnosed AF between October 2004 and November 2008 and at least 1 internal medicine/primary care or cardiology outpatient encounter within 90 days after diagnosis. The primary outcome was prescription of warfarin. Results In 141,642 patients meeting the inclusion criteria, the mean age was 72.3 +/- 10.2 years, 1.48% were women, and 25.8% had cardiology outpatient care. Cardiology-treated patients had more comorbidities and higher mean CHADS2 scores (1.8 vs 1.6, P < .0001). Warfarin use was higher in cardiology-treated vs primary care only-treated patients (68.6% vs 48.9%, P < .0001). After covariate and site-level adjustment, cardiology care was significantly associated with warfarin use (odds ratio [OR] 2.05, 95% CI 1.99-2.11). These findings were consistent across a series of adjusted models (OR 2.05-2.20), propensity matching (OR 1.98), and subgroup analyses (OR 1.58-2.11). Warfarin use in primary-care-only patients declined from 2004 to 2008 (51.6%-44.0%, P < .0001), whereas the adjusted odds of warfarin receipt with cardiology care (vs primary care) increased from 2004 to 2008 (1.88-2.24, P < .0001). Conclusion In patients with newly diagnosed AF, we found large differences in anticoagulation use by treating specialty. A divergent 5-year trend of risk-adjusted warfarin use was observed. Treating specialty influences stroke prevention care and may impact clinical outcomes. (Am Heart J 2013;165:93-101.e1.)