Clinical Question

Is aspirin as effective as rivaroxaban (Xarelto) for prevention of venous thromboembolism (VTE) after total hip arthroplasty (THA) or total knee arthroplasty (TKA)?

Bottom Line

Extended prophylaxis with low-dose aspirin is similar in efficacy to rivaroxaban for the prevention of symptomatic VTE following TKA or THA. Aspirin is cheap, widely available, and effective, making it a good alternative to the more costly direct oral anticoagulants. (Level of Evidence = 1b)

Synopsis

In this study, investigators tested the efficacy of aspirin (81 mg) compared with rivaroxaban (10 mg) for extended VTE prophylaxis following TKA or THA. All patients in the study initially received in-hospital prophylaxis with rivaroxaban, 10 mg daily for five days, following surgery. Patients randomized to the rivaroxaban group (n = 1,718) continued this treatment, whereas those randomized to the other group (n = 1,709) started aspirin, 81 mg daily. Additionally, patients taking preoperative aspirin (81 mg) were allowed to continue its use in the postoperative phase. Study treatment was continued for nine additional days in patients who underwent TKA and 30 additional days in patients who underwent THA. The two pills, rivaroxaban or aspirin, were administered in identical gelatin capsules. Patients in the two groups had similar baseline characteristics and were followed for 90 days. In the intention-to-treat analysis, low-dose aspirin was noninferior to rivaroxaban for the primary efficacy outcome of symptomatic proximal deep venous thrombosis or pulmonar y embolism (0.64% vs. 0.70%; P < .001 for noninferiority). For the primary safety outcome of major bleeding or clinically relevant nonmajor bleeding, there was no significant difference detected between the two groups (1.29% in aspirin group vs. 0.99% in rivaroxaban group; P = .43).

Study design: Randomized controlled trial (double-blinded)

Funding source: Government

Allocation: Concealed

Setting: Inpatient (any location) with outpatient follow-up

Reference:AndersonDRDunbarMMurnaghanJet alAspirin or rivaroxaban for VTE prophylaxis after hip or knee arthroplasty. N Engl J Med2018;378(8):699–707.