In patients with venous thromboembolism at equipoise for further anticoagulation therapy, treatment with a 10-mg dose of rivaroxaban (Xarelto) had comparable efficacy to a 20-mg dose, with both leading to fewer recurrences than treatment with aspirin. There were no statistically significant differences in clinically relevant nonmajor bleeding between the three groups.
The study’s conclusions are limited to relatively healthy patients such as the ones who were selected for the study.
The findings were presented at the annual meeting of the American College of Cardiology and published simultaneously in the New England Journal of Medicine (N Engl J Med 2017 March 18. doi: 10.1056/NEJMoa1700518).
Anticoagulants are the primary treatment for prevention of venous thromboembolism recurrences, but the medications are often stopped after 6-12 months because of concerns about bleeding. To counter that issue, physicians may prescribe lower doses of anticoagulants such as rivaroxaban, or substitute aspirin.
The work follows another recent study of apixaban (Eliquis), which showed that a 2.5-mg twice-daily dose performed the same as did a 5.0-mg twice-daily dose in the prevention of venous thromboembolism recurrence (N Engl J Med. 2013;368:699-708).
“I think the story is kind of the same here,” said David Garcia, MD, professor of hematology at the University of Washington, Seattle, who was one of the principal investigators in the trial.
Patients with unprompted venous thromboembolism are increasingly being offered anticoagulant therapy to prevent recurrences. Those drugs have inherent bleeding risks, but the newer drugs and even warfarin are becoming safer. Even so, “as we embark on that, one has to remember that the risk of anticoagulants is cumulative. It may only carry a risk of 1% per year of major hemorrhage, but if the patient has to take it for 10 or 20 or 30 years, it’s a nontrivial risk of major bleeding over that time,” said Dr. Garcia.
The researchers conducted the Reduced-Dose Rivaroxaban in the Long-Term Prevention of Recurrent Symptomatic Venous Thromboembolism (EINSTEIN CHOICE) trial, in which 3,365 patients from 24 sites were randomized to receive 20 mg rivaroxaban, 10 mg rivaroxaban, or 100 mg aspirin for up to 1 year following an initial 6-12 months of treatment with anticoagulation therapy.
During a median follow-up of 1 year, 4.4% of patients on aspirin experienced a recurrence, compared with 1.5% of patients in the 20-mg rivaroxaban group (hazard ratio versus aspirin, 0.34; 95% confidence interval, 0.20-0.59; P less than .001), and 1.2% in the 10-mg rivaroxaban group (HR versus aspirin, 0.26; 95% CI, 0.14-0.47; P less than .001). There was no statistical significance between the two doses of rivaroxaban.
The rates of fatal thromboembolism were similar, at 0.2% in the 20-mg rivaroxaban group, 0% in the 10-mg group, and 0.2% in the aspirin group.
Major bleeding occurred in 0.5% of patients in the 20-mg rivaroxaban group, in 0.4% of the 10-mg rivaroxaban group, and 0.3% in the aspirin group. Nonmajor, clinically relevant bleeding was also similar between groups, at 2.7% in the 20-mg group, 2.0% in the 10-mg group, and 1.8% in the aspirin group. These differences were not statistically significant.
The study is good news for clinicians as they help patients decide whether to undergo preventive therapy. “Even before the newer agents arrived on the market, we had moved the needle a lot in terms of maximizing the safety of warfarin. I think these drugs take it to yet another level,” said Dr. Garcia.
Bayer Pharmaceuticals funded the study. Dr. Garcia has received honoraria from Bristol-Meyers Squibb, Pfizer, and Boehringer Ingelheim.