Aspirin is as effective as rivaroxaban (Xarelto) for venous thromboembolism (VTE) prophylaxis after knee or hip surgery, according to a new study. About 1,800 patients undergoing hip arthroplasty and 1,600 patients undergoing knee arthroplasty were treated with five days of rivaroxaban postoperatively. The hip patients were randomized to 30 days of continued rivaroxaban or aspirin 81 mg, while the knee patients were randomized to nine days of rivaroxaban or aspirin. All patients were followed for 90 days for symptomatic VTE and bleeding complications. Venous thromboembolism occurred in 0.64% of subjects in the aspirin group and in 0.70% of subjects in the rivaroxaban group (95% confidence interval [CI], -0.55 to 0.66; P < 0.001 for noninferiority and P = 0.84 for superiority). Major bleeding occurred in 0.47% of the aspirin patients and 0.29% of rivaroxaban patients (95% CI, -0.65 to 0.29; P = 0.42) while clinically important bleeding occurred in 1.29% of the aspirin group and 0.99% of the rivaroxaban group (95% CI, -1.07 to 0.47; P = 0.43). The authors concluded that among hip or knee arthroplasty patients who receive five days of postoperative rivaroxaban, extended prophylaxis with aspirin was not significantly different from rivaroxaban in the prevention of symptomatic VTE (N Engl J Med 2018;78:699-707).

An accompanying editorial suggested that the very low rates of bleeding and thrombosis seen with the “relatively inexpensive and user-friendly aspirin-based strategy” has established “a prophylaxis regimen against which all strategies to prevent thromboembolism after joint replacement will be compared.” (N Engl J Med 2018;378:762-763)