Comparing stroke prevention therapy of direct oral anticoagulants and vitamin K antagonists in patients with atrial fibrillation: a nationwide retrospective observational study

BACKGROUND: Direct oral anticoagulants (DOACs) are not only increasingly being used for the initial stroke prevention therapy but progressively also substitute vitamin K antagonist (VKA) treatment in patients with non-valvular atrial fibrillation (AF). DOACs have been compared regarding therapeutic efficacy and adverse outcomes to warfarin in several pivotal studies and showed non-inferiority in terms of stroke prevention and superiority in terms of bleeding complications. However, comprehensive comparative studies are lacking for phenprocoumon, a VKA prescribed frequently outside the USA and the UK and accounting for 99% of all VKA prescriptions in Germany. Patients treated with phenprocoumon seem to meet more often international normalized ratio values in the therapeutic range, which may have implications concerning their efficacy and safety. This study aims at comparing the risk of stroke and bleeding in phenprocoumon- and DOAC-treated patients with AF in an adequately powered observational study population. METHODS: Retrospective analysis of stroke and bleeding incidence of 837,430 patients (1.27 million patient years) treated with DOAC or phenprocoumon for stroke prevention in German ambulatory care between 2010 and 2017. Relative risks of stroke and bleeding were estimated by calculating cox regression-derived hazard ratios (HR) and 95% confidence intervals (CI) of propensity score-matched cohorts. RESULTS: Patients treated with DOAC had an overall higher risk for stroke (HR 1.32; CI 1.29–1.35) and a lower risk for bleeding (0.89; 0.88–0.90) compared to phenprocoumon. When analyzed separately, the risk for stroke was higher for dabigatran (1.93; 1.82–2.03), apixaban (1.52; 1.46–1.58), and rivaroxaban (1.13; 1.10–1.17) but not for edoxaban (0.88; 0.74–1.05). The risk for bleeding was lower for dabigatran (0.85; 0.83–0.88), apixaban (0.71; 0.70–0.73), and edoxaban (0.29; 0.17–0.51) but not for rivaroxaban (1.03; 1.01–1.04). CONCLUSIONS: This study provides a comprehensive view of the stroke and bleeding risks associated with phenprocoumon and DOAC use in Germany. Phenprocoumon may be preferable to DOAC treatment for the prevention of strokes in AF in a real-world population cared for in ambulatory care.