Oral rivaroxaban’s efficacy at reducing the risk of recurrent venous thromboembolism (VTE) was confirmed in two trials presented at the annual meeting of the American Society of Hematology. The agent was studied for treatment of deep-vein thrombosis (DVT) as well as for continued therapy after initial anticoagulation treatment for DVT or pulmonary embolism.
For the DVT study, the EINSTEIN Investigators randomized 3449 patients with symptomatic DVT to rivaroxaban or enoxaparin plus either warfarin or acenocoumarol for 3, 6, or 12 months. Rivaroxaban was taken twice daily (15 mg) for 3 weeks, with a maintenance dose (20 mg daily) for the remainder of the study period. Enoxaparin was taken at a weight-adjusted dose until the international normalized ratio was 2 or greater for 2 days and after a minimum of 5 days of treatment. Patients in both groups received a vitamin K antagonist throughout the study period.
Rivaroxaban significantly reduced DVT risk over enoxaparin (P <.001). Major bleeding or clinically relevant nonmajor bleeding, the primary safety outcome, occurred in 8.1% of patients in both groups.
For the continuation study, the investigators randomized 1200 patients with symptomatic DVT or pulmonary embolism who had been treated for 6 to 12 months with a vitamin K antagonist to rivaroxaban (20 mg daily) or placebo for an additional 6 to 12 months.
Treatment with rivaroxaban also significantly reduced the risk of recurrent VTE over placebo (P <.001). Nonfatal major bleeding, the safety end point, occurred in four patients in the rivaroxaban group compared with zero in the placebo group (P = .11).
These finding were also published online in the New England Journal of Medicine (December 3, 2010).