Abstract 18353: The Comparative Safety and Effectiveness of the Oral Anticoagulant (OAC) Dabigatran versus Warfarin Utilized in a Large Healthcare System in Non-valvular Atrial Fibrillation (NVAF) Patients

Objectives: This study evaluated the safety and effectiveness of dabigatran versus warfarin for stroke risk reduction in NVAF patients in routine clinical care using the Department of Defense Military Health System database. Methods: In this retrospective cohort study, patients were included if they had an AF diagnosis within 12 months prior to first OAC treatment, were 18-89 years, and had a first prescription claim for either dabigatran or warfarin between 01-Oct-2010 and 31-Jul-2012 (index date). Patients were excluded if they had heart valve disorders or prosthetic heart valves, transient causes of AF, or any OAC use during the baseline period. Patients were censored when their prescriptions exceeded a 30 day allowable gap, at OAC switch, at disenrollment, at death, or at study end. A total of 14,813 dabigatran and 24,500 warfarin patients were available for propensity score matching (PSM). PSM based on baseline demographics and clinical characteristics was achieved 1:1 with 12,793 matched subjects per group (within a 0.20 caliper of standard deviation). Comparisons of safety and effectiveness outcomes were made based on Cox-proportional hazards models of PSM groups. All FDA-approved dosages were included in this analysis. Results: Results are summarized in Table 1. Conclusions: Hazard ratios in the post-PSM dabigatran cohort suggest that there is a lower likelihood for stroke, hemorrhagic stroke, major intracranial bleeding, major urogenital and other bleeding, MI, and death than in the warfarin cohort. The hazard ratio in the post-PSM dabigatran cohort suggests a higher likelihood for major lower GI bleeding, but a lower likelihood for intracranial, urogenital, and other bleeding than seen with warfarin. These results are generally consistent with findings of the randomized controlled clinical trial, RE-LY, and support that the benefits of dabigatran demonstrated in clinical trials also may be achieved in a broad population receiving routine clinical care.