Underutilization of warfarin for stroke prophylaxis in patients with atrial fibrillation or atrial flutter in Korea

Objective: Anticoagulation therapy with warfarin is recommended for stroke prevention in patients with atrial fibrillation (AF) or atrial flutter (AFL) whose risks for stroke are high. However, previous studies suggest that warfarin is markedly underused. This study aims to investigate the incidence and risk factors of warfarin underutilization in patients with high risk of stroke in Korea. Methods: This was a cross-sectional study using the data of 2009 from National Patients Sample compiled by the Health Insurance Review and Assessment Service. Patients with high risk of thromboembolism were identified with congestive heart failure, hypertension, age >= 75 years, diabetes, and prior stroke (CHADS2) score >= 2. High-risk patients of bleeding were excluded using Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) score >4. Warfarin and antithrombotic therapy underutilization were defined and estimated in high-risk patients. Any demographic and clinical factors associated with warfarin and antithrombotic therapy underutilization were explored using a logistic regression model. Results: Of the national patient sample, 15,885 patients were identified with AF or AFL. Among them, a total of 8475 patients who had an admission history, CHADS2 >= 2, and ATRIA score <= 4 were included in the analysis. From the study sample, warfarin underutilization and antithrombotic therapy underutilization were estimated to be 64.0% and 20.4%, respectively. Predictors of warfarin underutilization include female sex, age >= 80 years, lower CHADS2 score, and insurance type (Medical Aid program). Conclusions: A high portion of AF/AFL patients with CHADS2 score >= 2 were undertreated with warfarin. As ischemic stroke is one of the leading causes of death in Korea, a more aggressive approach to prevent stroke in patients with AF/AFL is required. (C) 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.