Aspirin monotherapy sufficient for venous thromboembolism prevention after arthroplasty

In patients who have undergone total hip or total knee arthroplasty, postoperative treatment with aspirin alone is as good as a strategy of using rivaroxaban followed by aspirin in terms of preventing symptomatic venous thromboembolism, with no significant difference in bleeding events, according to the EPCAT III trial.

A total of 5,365 patients were randomly assigned to receive once-daily thromboprophylaxis with either 81 mg of aspirin (n=2,718) or 10 mg of oral rivaroxaban (n=2,647) for the first 5 days after total hip or total knee arthroplasty. All patients received further thromboprophylaxis with 81 mg of aspirin daily for 9 additional days in the group of patients who underwent knee arthroplasty and for 30 additional days in the group of those who underwent hip arthroplasty.

The primary outcome was symptomatic venous thromboembolism, which included proximal deep-vein thrombosis and pulmonary embolism, over 90 days of follow-up. Bleeding complications were also assessed as the safety outcome.

Venous thromboembolism occurred in 0.48 percent of patients in the aspirin-alone group vs 0.45 percent of those in the rivaroxaban–aspirin group. The risk difference was 0.02 percentage points (95 percent confidence interval [CI], −0.34 to 0.39), below the noninferority margin of 0.7 percentage points (p<0.001 for noninferiority).

Likewise, major bleeding or clinically relevant nonmajor bleeding events did not significantly differ between the two groups, occurring in 1.66 percent of patients in the aspirin-alone group and in 2.04 percent of those in the rivaroxaban–aspirin group (risk difference, −0.38 percent, 95 percent CI, −1.11 to 0.34).