Trends in Oral Anticoagulation Therapy Among Korean Patients With Atrial Fibrillation: The KORean Atrial Fibrillation Investigation

Background and Objectives: Anticoagulation with vitamin K antagonists (VKAs) such as warfarin provides effective stroke prophylaxis in patients with atrial fibrillation (AF). We conducted a large multicenter survey of Korean patients with AF to determine trends in VKA use. Subjects and Methods: Eligible patients were adults with AF that had been prescribed VKAs. Medical records from a total of 5616 patients {mean age 63.6${\pm}$12.2 years, male 3150 (56.1%)} in 27 hospitals from Jan. 2001 to Oct. 2007 were reviewed. Results: The mean international normalized ratio (INR) was 2.04${\pm}$0.64, and mean dosage of VKA was 3.66${\pm}$1.50 mg. Individuals in their sixties (1852 patients) accounted for about one third of patients studied. As patients grew older, INR increased and VKA dosage decreased. The dosage of VKA in male patients was larger than that in females for all ages. A total of 2146 (42.4%) patients had an INR of 2-3, and less than 40% patients in their sixties had an INR within optimal range. The dosage of oral anticoagulant for optimal INR level was 3.71 mg. Conclusion: In this study, less than half of the Korean patients with AF on VKA reached the therapeutic range of INR. Mean dosage of VKA was 3.66${\pm}$1.50 mg, and the dosage of oral anticoagulant for optimal INR level was 3.71 mg, which decreased with age.