End of study transition from study drug to open-label vitamin K antagonist therapy: the ROCKET AF experience

To evaluate the previously reported excess of thromboembolic events during the 30 days after the end of study (EOS) visit when participants transitioned from blinded therapy to open-label vitamin K antagonist. At the EOS visit, open-label vitamin K antagonist was recommended, and the international normalized ratio (INR) was not to be measured until 3 days later to preserve blinding. We analyzed transition strategies, clinical outcomes, and INR values. Event rates are per 100 patient-years. A total of 9248 (65%) participants were taking study drug at EOS, and, between days 3 and 30, an excess of stroke and systemic embolic events were observed in participants assigned to rivaroxaban (rivaroxaban 22 events, event rate 6.42; warfarin 6 events, event rate 1.73; hazard ratio, 3.72; 95% confidence interval, 1.51-9.16; P=0.0044). No INR values were reported for ≈5% of participants transitioned to warfarin. By 30 days after EOS, 83% of the warfarin group and 52% of the rivaroxaban group had ≥1 therapeutic INR value. Median time to first therapeutic INR was 3 days in the warfarin group and 13 days in the rivaroxaban group. The excess of events at EOS was likely because of a period of inadequate anticoagulation in rivaroxaban participants switched to vitamin K antagonist therapy. If transition from rivaroxaban to vitamin K antagonist is needed, timely monitoring and careful dosing should be used to ensure consistent and adequate anticoagulation.