Bleeding Risk of Warfarin and Direct Oral Anticoagulants in Younger Population: A Historical Cohort Study Using a Japanese Claims Database.

A historical cohort analysis of the Japan medical data center (JMDC) claims databases was performed to compare the incidence rates of bleeding events with warfarin (WF) versus direct oral anticoagulant (DOAC) treatment in patients with non-valvular atrial fibrillation. The aim of this study is to clarify the risk factors for bleeding events in younger patients newly treated with WF or DOAC in clinical practice setting. Patients who newly initiated WF or DOAC treatment from April 2012 to March 2015 were selected from the JMDC claims database. A 1:1 propensity score matching analysis was used for new users of WF or DOAC. Kaplan-Meier curves were generated to depict the time to bleeding event (total bleeding events, gastrointestinal hemorrhage, and intracranial hemorrhage) during the follow-up period. Cox proportional regression models were used to estimate the hazard ratios for total bleeding events caused by oral anticoagulants. Overall, 2,046 patients (503 WF and 1,543 DOAC) were included. After applying propensity score matching, Kaplan-Meier analysis of the WF and DOAC groups displayed comparable incidences of total bleeding events, gastrointestinal hemorrhage, and intracranial hemorrhage. Cox proportional hazards modeling showed that the use of WF was not associated with total bleeding events compared with DOAC (hazard ratio: 1.21, 95% confidence interval: 0.93-1.54, p = 0.15). This historical cohort study using a claims database indicates that the bleeding risk of DOAC was comparable to that of WF in Japanese younger population.