Hamilton, Ontario—In terms of safety and effectiveness, aspirin has been considered a gold standard in preventing recurrence of venous thromboembolism. 

A new study suggests, however, that another drug, the blood thinner rivaroxaban, is as safe, but is more effective. A report published recently in the New England Journal of Medicine points out that aspirin is often the agent of choice because it is considered less risky than long-term treatment with blood thinners because of concerns about the likelihood of bleeding issues. 

The large international study of 3,396 patients with venous thromboembolism in 31 countries indicates that rivaroxaban is more effective than aspirin without a significant increase in risks.

“Not only that, but in testing two doses of rivaroxaban, we found that we have the option of lowering the daily dose for extended treatment,” explained Jeffrey Weitz, MD, principal investigator of the study and professor of medicine and biochemistry and biomedical sciences at the Michael G. DeGroote School of Medicine at McMaster University. “This will ease the long-term concerns of both patients and their doctors.”

For the study from March 2014 to March 2016, participants were divided into three groups—one receiving a daily 20-mg dose of rivaroxaban, one getting a 10-mg dose of rivaroxaban, and the third receiving a 100-mg dose of aspirin—for up to 12 months after they had received treatment for their initial clot.

Results indicate that patients taking aspirin had the highest rate of recurrent blood clots, at 4.4%, compared to 1.5% for those taking 20 mg of rivaroxaban and 1.2% for those taking 10 mg of rivaroxaban. 

Yet no statistically significant differences in bleeding side effects were detected among the groups: The rates of major bleeding were 0.3% in the group taking aspirin, and 0.5% and 0.4% in the groups taking 20 mg and 10 mg of rivaroxaban, respectively.

The study was presented at the American College of Cardiology’s 66th Annual Scientific Sessions by co-author Philip Wells, MD, MSc, of The Ottawa Hospital and the University of Ottawa.

“We know from previous studies that only about 40 percent of venous thromboembolism patients are actually on long-term blood thinners,” Wells said. “We hope that this study, which shows the blood thinner rivaroxaban, is as safe as aspirin but much more effective at preventing future clots, will convince patients and their physicians to continue life-long medication that can prevent potentially dangerous blood clots.”
« Click here to return to Weekly News Update.