Allan S. Brett, MD reviewing Weitz JI et al. N Engl J Med 2017 Mar 18. Crowther MA and Cuker A. N Engl J Med 2017 Mar 18.
In a 1-year study, rivaroxaban was more effective by several percentage points and did not confer excess bleeding risk.
The duration of guideline-recommended antithrombotic therapy for patients with venous thromboembolism (VTE) ranges from 3 months to indefinite, depending on whether the VTE is provoked or unprovoked and on patients' bleeding risks (NEJM JW Emerg Med Feb 2016 and Chest 2016; 149:315). For long-term prevention of recurrent VTE, options include warfarin, direct-acting oral anticoagulants, and aspirin; among the anticoagulants, guidelines recommend direct-acting anticoagulants over warfarin, unless substantial renal impairment is present. Indirect comparisons suggest that direct-acting oral anticoagulants are more effective than aspirin but are more likely to cause serious bleeding. Now, we have a head-to-head, randomized, double-blind trial.
Industry-supported researchers enrolled 3396 adults with VTE; half had isolated deep venous thrombosis, and half had pulmonary embolism. All patients had completed 6 to 12 months of anticoagulation. VTE was considered to be provoked in ≈60% of patients and unprovoked in 40%. Patients received daily rivaroxaban (Xarelto; 20 mg), rivaroxaban (10 mg), or aspirin (100 mg). All patients had creatinine clearance ≥30 mL/minute.
At 1 year, rates of symptomatic recurrent VTE with 20-mg rivaroxaban, 10-mg rivaroxaban, and aspirin were 1.5%, 1.2%, and 4.4%, respectively; differences between rivaroxaban and aspirin were significant. The difference in event rates between rivaroxaban and aspirin was somewhat larger for unprovoked VTE (≈1.6% vs. 5.6%) than for provoked VTE (≈1.2% vs. 3.6%). Rates of major bleeding were similar in the three groups (0.5%, 0.4%, and 0.3%).
Weitz JI et al. Rivaroxaban or aspirin for extended treatment of venous thromboembolism. N Engl J Med 2017 Mar 18; [e-pub].
Crowther MA and Cuker A.Reduced-intensity rivaroxaban for the prevention of recurrent venous thromboembolism. N Engl J Med 2017 Mar 18; [e-pub].