br Conclusions br Source of funding br Conflict of

Conclusions
Source of funding
Conflict of interest
Acknowledgments
Introduction Atrial fibrillation (AF) is an arrhythmia that is commonly seen and occurs more often in the elderly. In Japan, the overall prevalence of all types of AF based on the data from periodic health examinations was estimated to be 0.56% [1]. Considering the aging population in Japan, it is estimated that more than 1 million individuals would be suffering from the disease in the year 2030. The number of AF patients would increase when patients with paroxysmal AF are included. Nonvalvular atrial fibrillation (NVAF) associated with lifestyle-related diseases, such as Lenalidomide and diabetes mellitus, is predominant among the patient population [1]. For the prevention of stroke in NVAF patients, appropriate antithrombotic therapy should be selected after a risk assessment of cerebral infarction [2]. In the past, warfarin was the only anticoagulant drug indicated for NVAF in Japan but less than 60% of high-risk NVAF patients are treated with the drug in real-world practice [3]. The major reason for under-use of warfarin is the difficulty in controlling anticoagulation intensity: it requires dose adjustments by routine monitoring of prothrombin time-international normalized ratio (PT-INR) because of its narrow therapeutic range, and it is subject to pharmacodynamic and pharmacokinetic interactions with concomitant drugs and diet. Dabigatran etexilate (dabigatran) has been developed as a new anticoagulant (non-vitamin K antagonist oral anticoagulant; NOAC) to solve the above issues. Dabigatran is a direct competitive inhibitor of thrombin, which is the critical factor in the blood-clotting cascade, thereby suppressing the conversion of fibrinogen to fibrin, and leading to the prevention of thrombosis [4]. In the RE-LY study [5], a randomized global phase III study, which included Japanese patients, the favorable efficacy and safety of dabigatran compared to that of INR-adjusted warfarin was demonstrated. The Japanese Guidelines for Pharmacotherapy of AF (revised in 2013) [6] recommend dabigatran for NVAF patients whose CHADS2 scores are 1 or higher, taking into account the overall results of the RE-LY study and its sub-analysis, showing the efficacy and safety of dabigatran for patients with CHADS2 score of 1 or higher. In the United States [7] and Denmark [8,9], large-scale investigations performed by the FDA and independent academic institutions, respectively, have meanwhile confirmed the effectiveness and safety of dabigatran in the real world.
Material and methods
Results
Discussion Switchers had a higher risk of stroke with a CHADS2 score of at least 2, whereas non-switchers mostly had a CHADS2 score of 0 or 1. Permanent AF was most common in Switchers, whereas paroxysmal AF was most common in non-Switchers. Medication adherence was good with >90% measured for the first 3 months of treatment period. In the RE-LY study [5], patients with a CHADS2 score of 2 accounted for the highest proportion of about 35%; in the Asian subgroup [10] in particular, patients with CHADS2 scores ≥3 accounted for 36.8%. In the present PMS study, however, patients with CHADS2 scores of 0 or 1 accounted for 44.9%, indicating that more NVAF patients at a lower risk for stroke were observed in real clinical practice than in the RE-LY study. The J-RHYTHM Registry [11], which is a Japanese non-interventional study, showed quite comparable risk scores at baseline for stroke [mean CHADS2 score: 1.8±1.3 (this study) vs. 1.7±1.2; proportion of patients with CHADS2 scores of 0 or 1: 44.9% and 49.6%, respectively]. The Fushimi AF Registry [12] is a non-interventional study to enroll AF patients in Fushimi-ku, Kyoto that is assumed to represent a typical urban community in Japan. The mean CHADS2 score was higher at 2.09±1.35 and the proportion of patients with CHADS2 scores of 0 or 1 was lower at 36.9% in the Fushimi AF Registry than in the present study.