AC regimens have also demonstrated better preventive effects

AC regimens have also demonstrated better preventive effects in terms of stroke than AP regimens [18–20], whereas major or minor bleeding events in Japanese patients with cardiovascular diseases were reported to be more frequent in patients taking AC than in those taking AP regimens [21]. To understand the risk/benefit balance on antithrombotic therapy in actual treatment, we investigated the change of antithrombotic regimens in cases in which bleeding events occurred. After experiencing bleeding events, 62.5% of patients with AP monotherapy changed to AC and 37.5% to AP+AC, whereas among AP+AC patients, 50% changed to AC monotherapy. Conversely, among patients with AC monotherapy, only 13.9% patients changed to AP or AP+AC regimens. AC monotherapy was continued for 86.1% of patients. The PT–INR was lower in N patients than in S or P patients (1.83, 2.01, and 2.00, respectively). These values are included in the recommended lowest relative risk value for ischemic stroke and intracranial hemorrhage for Japanese patients [15]. In conclusion, the presence of atherosclerotic diseases such as histone acetyltransferase and peripheral artery diseases is a major factor determining the selection of antithrombotic monotherapy, and the CHADS2 score and comorbidity are major factors determining the combination regimen with AP and AC. Bleeding history was not a factor determining antithrombotic therapy. Conversely, bleeding history is the major factor determining the selection of OACs in Japan. This study was limited by the lack of information on the economic background and treatment preference of patients. In addition, it was limited by the exclusion of dabigatran users. The patient characteristics in European and US studies [22,23] showed differences between patients using warfarin and dabigatran regimens, such as in terms of CHADS2 scores and comorbidities. We therefore intend to compare our results with the PMS background data for dabigatran.
Conflict of interest This study was supported financially by Nippon Boehringer Ingelheim Co. Ltd. (Project number 10011060003) on the basis of a consignment contract. KK was an employee of Nippon Boehringer Ingelheim until January 2013. TK was an employee of Nippon Boehringer Ingelheim until August 2013. There are no other conflicts of interests.
Acknowledgment
Introduction Atrial fibrillation (AF) is the most common tachyarrhythmia and is a risk factor for stroke [1–4]. Anticoagulant therapy reduces the risk of AF-related stroke [5]. Dabigatran etexilate is an oral direct thrombin inhibitor, which is the first direct-acting oral anticoagulant. The Randomized Evaluation of Long-term Anticoagulation Therapy (RE-LY) trial demonstrated that 110mg of dabigatran was associated with rates of stroke/systemic embolism that were similar to the rates observed in patients taking warfarin; moreover, patients taking dabigatran exhibited a lower rate of major hemorrhage compared with that in patients taking warfarin. Dabigatran at a dose of 150mg was associated with lower rates of stroke/systemic embolism but showed similar rates of major hemorrhage compared with warfarin treatment in non-valvular AF (NVAF) patients at risk of stroke [6]. A sub-analysis of 326 Japanese subjects in the RE-LY trial demonstrated that the efficacy and safety profiles of dabigatran for Japanese AF patients were essentially the same as those for the overall study population [7]. In “real-world” practice, anticoagulant therapy is indicated for patients whose clinical profiles are not addressed in randomized clinical trials. However, few reports have focused on the effectiveness and safety of dabigatran treatment in “real-world” Japanese NVAF patients. The aim of this study is to assess the effectiveness and safety of dabigatran versus warfarin in Japanese NVAF patients who recently initiated drug treatment.
Material and methods
Results
Discussion Our propensity-matched cohort study of “real-world” NVAF patients who initiated treatment with dabigatran or warfarin showed that the incidence of stroke/systemic embolism in patients taking dabigatran was similar to that in patients taking warfarin, whereas the incidence of major bleeding was lower in the dabigatran group. In our propensity-matched patients, the proportion of females (28%), the proportion of heart failure (17%), the proportion of hypertension (62%), the mean CHADS2 score (1.9), and the proportion of CHADS2 ≥2 (55%) were lower compared with those in the RE-LY trial overall/Japanese (37%/23%, 32%/31%, 79%/-, 2.1/2.2, and 66%/69%, respectively) [6,7]. These differences suggest that our patients have a slightly lower cerebrovascular risk. The majority of our patients received a dabigatran dose of 110mg, and the current results are comparable to those observed in patients taking the 110-mg dose of dabigatran in the RE-LY trial [6].