Drug Utilization Pattern of Oral Anticoagulants in Patients with Atrial Fibrillation: A Nationwide Population-Based Study in Korea

Introduction Treatment persistence for anticoagulant therapy is important in preventing thromboembolism in nonvalvular atrial fibrillation (NVAF) patients. Understanding drug utilization pattern and treatment changes in oral anticoagulant (OAC) users may facilite better NVAF management. Thus, our study aimed to examine OAC treatment patterns preceding events leading to switch or discontinuation and medication adherence in Korean NVAF patients. Methods We conducted a drug utilization study on all Korean patients with atrial fibrillation (AF) newly prescribed OACs between July 2015 and November 2016 using the national claims data. We assessed treatment changes such as switching and discontinuation from index OAC and relevant events preceding the change and examined patient characteristics as predictors of changes that occurred among OAC users. Medication adherence was compared among OAC users by calculating the medication possession ratio (MPR). Results A total of 48,389 NVAF patients were identified who initiated OACs within the study period. Most initiated nonvitamin K antagonist oral anticoagulants (NOACs) (22% apixaban, 24% dabigatran, 37% rivaroxaban), and 18% initiated warfarin. The frequency of switch to another OAC was 8.8% for apixaban, 16.1% for dabigatran, 6.6% for rivaroxaban, and 19.1% for warfarin. The frequency of discontinuation was lower for apixaban (22.9%), dabigatran (26.3%), and rivaroxaban (25.7%) than warfarin (31.6%). Compared to warfarin, NOAC users were less likely to switch treatment. Thromboembolic event was the most common clinical event preceding switch from warfarin to NOAC and from NOAC to warfarin. Discontinuation of OAC was often preceded by a bleeding event. Patients who initiated apixaban showed significantly higher mean MPR compared to those on dabigatran and warfarin. Conclusion In real-world practice in Korea, we have observed treatment change to be common in OAC users. Our results indicate better medication adherence with NOACs than with warfarin. (ClinicalTrials.gov registration number NCT03572972). Plain language summary Anticoagulants are drugs that thin blood with the purpose of preventing thromboembolic disease (e.g., stroke), which is a disease occurring when a blood clot forms or blocks vessel. Maintaining treatment for anticoagulation is important to prevent stroke in atrial fibrillation (AF) patients. To understand current drug usage pattern and treatment changes related to oral anticoagulants (OAC) we examined OAC treatment patterns and preceding events that led to drug switch or stop and medication maintenance by Korean AF patients. The study was conducted by utilizing the Korean national claims data from July 2015 to November 2016. All AF patients who newly started taking OAC were included in the analysis. In total, 48,389 patients were identified with most (83%) taking nonvitamin K antagonist oral anticoagulants (NOAC), which are newer generation blood thinners, including apixaban, dabigatran, and rivaroxaban, and 18% taking warfarin, the conventional blood thinner. Compared to warfarin, NOAC users were less likely to switch to other treatment. NOAC users discontinued the treatment less frequently than warfarin users. Thromboembolic events commonly preceded switch between OACs. Patients who stopped taking OACs were often confronted with a bleeding event before stopping treatment. Apixaban takers showed higher treatment persistence compared to dabigatran or warfarin users. In this study, we determined that treatment change is common in OAC-using patients. The results suggest that NOAC users may better adhere to treatment than warfarin users.