In the first head to head trial, rivaroxaban was more effective than aspirin.
Aspirin is less effective than rivaroxaban (Xarelto/Bayer, Janssen) in preventing clots without putting patients at significant risk of bleeding,
According to a study presented today at ACC Scientific Sessions, rivaroxaban reduced clot recurrences in patients at elevated risk of such clots by more than three-fold compared to aspirin. The findings should clarify conflicting results in other studies that suggested aspirin had a lower bleeding risk.
But in the study, known as EiINSTEIN CHOICE and reported today-- the first to directly compare the two drugs-- researchers found there was no significant increase in serious bleeding with rivaroxaban, said Philip Wells, MD, chief of the department of medicine at the University of Ottawa and Ottawa Hospital in Canada.
"This is highly effective and we hope physicians will prescribe it [rivaroxaban] more frequently," Wells said discussed the study at a news conference this morning.
"Physicians are reluctant to use anticoagulants and some data showed aspirin might be safer, but there was no difference," he explained.
Venous thromboembolism (VTE) usually occurs as deep vein thrombosis or can also be a pulmonary embolism. Patients who experience these events need to be on blood thinners, but some patients remain at elevated risk once the therapy is stopped.
The most common risk factors for VTE are cancer and immobility due to surgery or illness, Wells said.
In the study comparing the safety and effectiveness of rivaroxaban and aspirin, 3,396 patients average age 59 and 55% men were randomly assigned to get 10 mg of rivaroxaban, 20 mg of rivaroxaban, or 100 mg of aspirin once daily for up to 12 months.
The primary efficacy endpoint was recurrence of VTE. Secondary efficacy endpoints were deaths due to VTE and unexplained deaths for which VTE may have been a cause.
After a median follow-up of 351 days, 1.2% patients in the group getting the 10 mg dose and 1.5% getting the higher dose had a recurrence of VTE compared with 4.4% of patients getting aspirin.
The secondary efficacy endpoints were equivalent, the research team found.
Major bleeding occurred in 0.3% of patients getting aspirin. That rate was higher in patients getting rivaroxaban at 0.4% and 0.5% depending on whether they got the low dose or higher dose.
But the differences were not statistically significant, the researchers said.
“Rivaroxaban had significantly greater efficacy in preventing VTE recurrence without significantly increasing risk for major bleeding,” Wells said.
The study was published online in The New England Journal of Medicine. It was funded by Bayer.
In an accompanying editorial, Mark Crowther, MD, and Adam Cuker, MD noted that the study followed the AMPLIFY-EXT study, comparing apixaban (Eliquis/Bristol-Myers Squibb-Pfizer) with placebo in 2,482 patients with prior VTE who had completed 6 to 12 months of anticoagulation treatment for VTE. Results showed that extended anticoagulation with Eliquis twice daily reduced the risk of recurrent VTE (fatal or nonfatal).