Apixaban Safer Than Rivaroxaban for Venous Thrombosis Treatment

First head-to-head trial finds apixaban has lower bleeding risk than rivaroxaban

Mar. 13, 2026 at 1:48am

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The first clinical trial to directly compare two commonly used blood thinners, apixaban and rivaroxaban, for treating venous thrombosis found that apixaban has a significantly lower risk of bleeding complications compared to rivaroxaban, while being equally effective at preventing further blood clots.

Why it matters

Venous thrombosis, or blood clots in the veins, is a leading cause of cardiovascular death and a common issue for hospitalized patients. This trial provides important evidence to help physicians and patients choose the safer anticoagulant option for treating this condition.

The details

The COBRRA trial enrolled 2,760 participants across Canada, Australia, and Ireland and found that 7.1% of those taking rivaroxaban experienced clinically relevant bleeding after 3 months, compared to only 3.3% of those taking apixaban - more than double the bleeding risk. However, there was no significant difference in the rate of recurrent blood clots between the two drugs.

  • The COBRRA trial was conducted from 2025 to 2026.

The players

The Ottawa Hospital

The research institution that led the COBRRA trial.

Dr. Marc Rodger

The senior author of the study and Physician-in-Chief at the McGill University Health Centre, Senior Scientist at the Research Institute of the MUHC, and Affiliate Senior Scientist at The Ottawa Hospital.

Dr. Lana Castellucci

The lead author of the study, a senior scientist and thrombosis physician at The Ottawa Hospital and professor at the University of Ottawa.

Dr. Vivien Chen

The Thrombosis Lead Haematologist at Concord Hospital and professor of medicine at University of Sydney, who highlighted the global relevance of the trial's findings.

Jonathan Love

A clinical trial participant who was diagnosed with venous thrombosis and enrolled in the COBRRA study.

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What they’re saying

“These results clearly show that apixaban is the safer option for treating venous thrombosis. This trial provides highly anticipated evidence for physicians and should bring real peace of mind to venous thrombosis patients, who often live with the dual fear of blood clot recurrence and bleeding.”

— Dr. Lana Castellucci, Lead author, senior scientist and thrombosis physician at The Ottawa Hospital and professor at the University of Ottawa

“This practice-changing trial and its findings exemplify the powerful impact of academically led, government-funded clinical research in addressing questions that truly matter to patients.”

— Dr. Marc Rodger, Senior author, Physician-in-Chief at the McGill University Health Centre, Senior Scientist at the Research Institute of the MUHC, and Affiliate Senior Scientist at The Ottawa Hospital

“Because this was a real world, standard of care trial conducted across three countries, the findings have strong global relevance. Patients in Australia, Canada and Ireland were treated according to routine clinical practice, making the findings broadly applicable to diverse health systems and patient populations.”

— Dr. Vivien Chen, Thrombosis Lead Haematologist at Concord Hospital and professor of medicine at University of Sydney

What’s next

The results of the COBRRA trial are expected to influence clinical guidelines and lead to more widespread use of apixaban over rivaroxaban for treating venous thrombosis.

The takeaway

This landmark study provides clear evidence that apixaban is the safer anticoagulant option for patients recovering from venous thrombosis, with a significantly lower risk of bleeding complications compared to rivaroxaban. These findings will help physicians make more informed decisions to improve outcomes and quality of life for their patients.