Combo antithrombotic therapy increases bleeding risk

(HealthDay)—Patients with chronic coronary artery disease or peripheral artery disease treated with the combination of rivaroxaban and aspirin face a greater risk for bleeding versus patients treated with aspirin alone, according to a study published in the Sept. 24 issue of the Journal of the American College of Cardiology.

John W. Eikelboom, M.B.B.S., from Hamilton Health Sciences in Ontario, Canada, and colleagues report findings from the Cardiovascular Outcomes for People Using Anticoagulation Strategies study in which 18,278 patients were randomly assigned to either the combination of rivaroxaban (2.5 mg twice daily) and aspirin (100 mg once daily) or to aspirin alone (100 mg once daily). Participants were followed for a mean of 23 months. The authors assessed the differences in sites, timing, severity, and management of bleeding.

The researchers found that compared with aspirin alone, the combination treatment increased major bleeding defined by the modified International Society on Thrombosis and Hemostasis (ISTH; hazard ratio, 1.70) and defined by the original ISTH definition (hazard ratio, 1.78). The combination also increased the risk for minor bleeding (hazard ratio, 1.70) and the need for any red cell transfusion (hazard ratio, 1.97). The most common site of increased major bleeding was the gastrointestinal tract (hazard ratio, 2.15), and the increase in bleeding was predominantly in the first year after random assignment. Among those experiencing major bleeding, rates of treatment with platelets, clotting factors, or other hemostatic agents were similar between the groups.

"The reduction in cardiovascular death, stroke, or myocardial infarction continued to accrue after the first year, suggesting accumulating net clinical benefit over time," the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including Bayer.

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