Abstract 12249: Underuse and Underdose of Oral Anticoagulants for Patients With Atrial Fibrillation in Japan: From the Fushimi Af Registry
Background: Atrial fibrillation (AF) is a common arrhythmic disorder among the elderly, and is increasing significantly as the population ages (reportedly 0.6% of total population in Japan). AF increases the risk of thromboembolism, and oral anticoagulants (OAC) are highly effective in preventing it. Until recently, warfarin was the only OAC, but novel OACs have become available.
Methods: The Fushimi AF Registry, a community-based prospective survey, was designed to enroll all of the AF patients in Fushimi-ku, Kyoto, Japan. Fushimi-ku is densely populated with a total population of 283,000, and is assumed to represent a typical urban community in Japan. At present, we have enrolled 3,661 patients (1.3% of total population) from March 2011 to April 2013. One-year follow-up was completed in 2,548 patients as of April 2013.
Results: Among 2,548 patients, OAC was given in only 1,391 patients (54.6%) at baseline (warfarin 1,337, dabigatran 54, no OAC 1,157). At 1-year, OAC was given in 1,249 patients (55.0%) (warfarin 1,123, dabigatran 118, rivaroxaban 8, no OAC 1,022, unknown 277), indicating that OAC remained underused even after the release of novel OACs. Patients with OAC at baseline (n=1,391, 54.6%), compared with those without OAC (n=1,157, 45.4%), were older and had higher CHADS2 score (OAC vs. no OAC; 74.2 vs. 73.0 years of age: p≤0.01, and 2.31 vs. 1.78: p≤0.01). During one-year follow-up period, the incidence of the thromboembolic or bleeding events was as follows; stroke 2.7% vs. 2.8%, ischemic stroke 2.2% vs. 1.9%, hemorrhagic stroke 0.6% vs. 0.8%, transient ischemic attack 0.1% vs. 0.2%, systemic embolism 0.0% vs. 0.9%, major bleeding 1.5% vs. 1.9% (NS for all). Warfarin is reported to reduce the risk of stroke by more than 60%, and cause major bleeding 3% annually. However, in the patients under OAC (mainly warfarin), the incidence of stroke was higher, and bleeding was less than anticipated, suggesting that OAC are given in underdose because of concerns about bleeding complications.
Conclusion: The Fushimi AF registry represents the clinical profile of real-world Japanese AF patients. Underuse and underdose of OAC may result in the insufficient prevention of thromboembolic events and the relatively low incidence of bleeding events.
- © 2013 by American Heart Association, Inc.