Introduction: Venous thromboembolism (VTE) is a common, potentially fatal complication of major orthopaedic surgery. Although pharmacological thromboprophylaxis is recommended following total hip replacement (THR) for a minimum of 10 days, and up to 35 days, its extended use is not universally accepted – an effective, safe and convenient, oral anticoagulant would improve implementation of these recommendations. This trial compared short-term thromboprophylaxis using enoxaparin with extended thromboprophylaxis using rivaroxaban – a once-daily, oral, direct Factor Xa inhibitor – after THR, in the largest, prospective, randomized clinical trial conducted to date for the evaluation of the risk/benefit of extended prophylaxis.

Method: In this global, double-blind trial, 2509 patients undergoing THR were randomized to receive either subcutaneous enoxaparin 40 mg once daily (od), started the evening before surgery and continued for 10–14 days, followed by placebo until day 35±4 (short-term prophylaxis), or oral rivaroxaban 10 mg od, started 6–8 hours after surgery and continuing for 35±4 days (extended prophylaxis). Mandatory, bilateral venography was conducted on day 36±4. The primary efficacy endpoint was the composite of any deep vein thrombosis (DVT), non-fatal pulmonary embolism (PE), and all-cause mortality. The main secondary efficacy endpoint was major VTE (the composite of proximal DVT, non-fatal PE, and VTE-related death). Safety endpoints included the incidence of major and non-major bleeding.

Results: The incidence of the primary efficacy endpoint was significantly reduced with extended thromboprophylaxis with rivaroxaban compared with short-term enoxaparin (2.0% and 9.3%, respectively; p< 0.001; relative risk reduction [RRR] 79%), as was major VTE (0.6% versus 5.1%; p< 0.001; RRR 88%). The incidence of major bleeding was the same in both groups (0.1%). Non-major bleeding was reported in 6.5% of patients who received extended thromboprophylaxis with rivaroxaban and in 5.5% of those treated with short-term enoxaparin.

Conclusion: Extended duration thromboprophylaxis with rivaroxaban is both significantly more effective and adds no disadvantage, in terms of bleeding, when compared with short-term prophylaxis. These data suggest that extended thromboprophylaxis provides substantial benefits to patients undergoing THR and rivaroxaban provides a safe and effective option for this strategy.