Photo by Sage Ross
Aspirin tablets
Aspirin seems to be as effective as rivaroxaban for preventing venous thromboembolism (VTE) after total hip or knee replacement, according to research published in NEJM.
Researchers observed a similar incidence of VTE whether patients were randomized to receive aspirin or rivaroxaban prophylaxis starting 5 days after surgery, with all patients receiving rivaroxaban for the first 5 days after surgery.
There was no significant difference between the aspirin and rivaroxaban groups with regard to major bleeding or clinically important bleeding.
“We have always been very concerned about preventing blood clots in patients following major orthopedic surgery,” said study author David Zukor, MD, of Jewish General Hospital in Montreal, Quebec, Canada.
“It is the leading cause of preventable in-hospital death, so we always administer preventive therapy in conjunction with such surgeries. Rivaroxaban is known to be effective, but the great advantage of aspirin is that it is far less expensive, easily available, and has an excellent safety profile.”
Dr Zukor and his colleagues set out to compare aspirin and rivaroxaban in 3424 patients, 1804 who underwent hip replacement and 1620 who underwent knee replacement.
All patients took rivaroxaban (10 mg) for 5 days after surgery before being randomized to receive aspirin (81 mg daily, n=1707) or to continue with rivaroxaban (n=1717). The patients received this prophylaxis for an additional 9 days if they had knee replacement or for 30 days if they had hip replacement.
The researchers followed patients for 90 days, monitoring them for symptomatic VTE and major or clinically relevant nonmajor bleeding.
The rate of VTE was 0.64% (n=11) in the aspirin group and 0.70% (n=12) in the rivaroxaban group (difference, 0.06 percentage points; 95% confidence interval [CI], −0.55 to 0.66; P<0.001 for noninferiority, P=0.84 for superiority).
Major bleeding occurred in 0.47% (n=8) of patients in the aspirin group and in 0.29% (n=5) of those in the rivaroxaban group (difference, 0.18 percentage points; 95% CI, −0.65 to 0.29; P=0.42).
Clinically relevant nonmajor bleeding occurred in 1.29% (n=22) and 0.99% (n=17), respectively (difference, 0.30 percentage points; 95% CI, −1.07 to 0.47; P=0.43).
All bleeding events occurred at the surgical site, and most occurred within 10 days of randomization.
“These results are important,” said study author Susan Kahn, MD, of McGill University in Montreal.
“The protocols for preventing clots following major orthopedic surgery are well established. However, we are always interested in determining whether there are better options for treating our patients. We could well see aspirin emerge as a practical alternative to more expensive anticoagulants.”
Drs Kahn and Zukor both noted the need for additional trials that would include a randomized group of patients prescribed aspirin exclusively so as to test its efficacy directly against rivaroxaban.