Thromboembolic, bleeding, and mortality risks among patients with nonvalvular atrial fibrillation treated with dual antiplatelet therapy versus oral anticoagulants: A population-based study.

Background: Dual antiplatelet therapy (DAPT) with aspirin plus clopidogrel is used for stroke prevention in patients with atrial fibrillation (AF) who refuse to take use oral anticoagulants (OACs). However, clinical data comparing these treatments are limited.

Objective: The purpose of this study was to compare the clinical outcomes between DAPT and OAC in patients with AF.

Methods: A cohort study using a population-wide database of the Hong Kong Hospital Authority was performed. New patients with AF from 2010-2014 who were prescribed DAPT or OAC (warfarin or dabigatran) were followed until July 31, 2016. Outcomes were thromboembolism, bleeding, and death. Propensity score (PS) matching at a ratio of 1:2 was used to select DAPT users with characteristics similar to those of OAC users, analyzed using Poisson regression.

Results: Among 51,946 new patients with AF, 8520 users of OAC and DAPT were identified. The likelihood of receiving DAPT over OAC increased with older age and previous intracranial hemorrhage. Among DAPT users, the incidences of thromboembolism, death, and bleeding per 100 patient-years were 15.8, 17.6, and 5.1, respectively. Compared to DAPT users, PS-matched analysis indicated a lower incidence of thromboembolism and/or death among OAC users (dabigatran: incidence rate ratio [IRR] 0.32; 95% confidence interval [CI] 0.19-0.55; warfarin: IRR 0.58; 95% CI 0.36-0.95), with no significant differences in bleeding events.

Conclusion: DAPT users were at markedly increased risk for thromboembolism and death compared to OAC users. These findings indicate the need for improved stroke risk reduction strategies among patients taking DAPT and the opportunities for using OAC in high-risk groups to prevent additional events.