Key Points

Question  Is aspirin monotherapy noninferior to enoxaparin in preventing symptomatic venous thromboembolism (VTE) within 90 days following primary total hip or knee arthroplasty performed for osteoarthritis?

Findings  In this cluster-randomized, crossover trial that included 9711 patients, treatment with aspirin vs enoxaparin resulted in symptomatic VTE (including below-knee VTE) in 3.45% vs 1.82% of patients, respectively. The difference failed to meet the noninferiority margin of 1% and was statistically significant for superiority of enoxaparin.

Meaning  In patients undergoing hip or knee arthroplasty for osteoarthritis, aspirin compared with enoxaparin resulted in a significantly higher rate of symptomatic VTE, including below-knee VTE.