Purpose: Thromboprophylaxis is recommended for at least 10 days and up to 35 days following total hip replacement (THR). Rivaroxaban is an oral, direct Factor Xa inhibitor in advanced clinical development that showed promise in early clinical trials. The purpose of this randomized, double-blind, double-dummy, phase III study was to compare the efficacy and safety of oral rivaroxaban with subcutaneous enoxaparin for 5 weeks, to prevent venous thromboembolism (VTE) in patients undergoing primary THR.

Method: Patients received 10 mg rivaroxaban orally 6–8 hours after surgery and once daily thereafter, or 40 mg enoxaparin subcutaneously the evening before surgery (restarting 6–8 hours after surgery), and continued once daily. Thromboprophylaxis was administered for 35±4 days, and mandatory, bilateral venography was conducted the next day. The primary efficacy endpoint was the composite of any deep vein thrombosis (DVT), non-fatal pulmonary embolism (PE), and all-cause mortality. The primary efficacy analysis was a test for non-inferiority, followed by a test for superiority. Safety endpoints included major and non-major bleeding during the active treatment period.

Results: A total of 4541 patients were randomized to receive rivaroxaban or enoxaparin. Rivaroxaban significantly reduced the incidence of the composite of DVT, PE, and all-cause mortality compared with enoxaparin (1.1% vs 3.7%, respectively; p< 0.001; relative risk reduction [RRR] 70%). Rivaroxaban also significantly reduced the incidence of major VTE compared with enoxaparin (0.2% vs 2.0%, respectively; p< 0.001; RRR 88%). There were no significant differences in the incidence of major bleeding (0.3% vs 0.1%; p=0.178) or non-major bleeding (5.8% vs 5.8%; p=1.000) between rivaroxaban and enoxaparin, respectively. There was no evidence of cardiac or liver safety issues.

Conclusion: Oral, once-daily rivaroxaban was significantly more effective than subcutaneous, once-daily enoxaparin for extended thromboprophylaxis following THR. Rivaroxaban was not associated with an increased risk of bleeding and had a similar safety profile to enoxaparin. This trial demonstrated the efficacy and safety of a fixed, unmonitored dose of an oral, direct Factor Xa inhibitor – rivaroxaban – for extended thromboprophylaxis after THR.

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

Method: In this global, double-blind trial, 2509 patients undergoing THR were randomized to receive either subcutaneous enoxaparin 40 mg once daily (od), beginning 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 beginning 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: Extended thromboprophylaxis with rivaroxaban significantly reduced the incidence of both the primary efficacy endpoint (2.0% versus 9.3%, respectively; p< 0.001; relative risk reduction [RRR] 79%) and major VTE (0.6% versus 5.1%, respectively; p< 0.001; RRR 88%), compared with short-term enoxaparin. The incidence of major bleeding was 0.1% in patients receiving either extended or short-term thromboprophylaxis. Non-major bleeding was reported in 6.5% of patients receiving extended prophylaxis with rivaroxaban and 5.5% of those receiving short-term enoxaparin.

Conclusion: Extended duration thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin for the prevention of VTE in patients undergoing THR. Both regimens were associated with a similar incidence of bleeding. Extended thromboprophylaxis provides substantial benefits for patients undergoing THR and rivaroxaban provides a safe and effective option for this strategy.

Aims: To investigate the efficacy and safety of a new dosage regimen of the oral direct thrombin inhibitor ximelagatran, and its subcutaneous (sc) form melagatran, started in close proximity to surgery. Methods: In a randomised, double-blind, parallel-group study, duration 8–11 days, patients undergoing total hip or knee replacement (THR, n= 1856; TKR, n= 908) received either sc melagatran 2 mg immediately before surgery followed by sc 3 mg in the evening after surgery, and then by oral ximelagatran 24 mg bid as a fixed dose (the ximelagatran group), or sc enoxaparin 40 mg od, started the evening before surgery. Bilateral venography was performed on the final day of treatment. Results: The rate of proximal deep vein thrombosis plus pulmonary embolism was 2.3% in the ximelagatran group vs. 6.3% in the enoxaparin group (p< 0.000002; RRR 63.2%). The total rates of venous thromboembolism (VTE) were 20.3% vs. 26.6%, respectively (p< 0.0003; RRR 23.6%). Cases with symptomatic VTE were rare: 8 in the ximelagatran group and 12 in the enoxaparin group. Bleeding events were more common in the ximelagatran group compared with the enoxaparin group (3.3% vs. 1.2%) as were the transfusion rates (66.8% vs. 61.7%). Importantly, there were no differences in fatal bleeding, critical organ bleeding or bleeding requiring re-operation. Conclusion: Pre-operatively initiated sc melagatran followed by oral ximelagatran was superior in efficacy to enoxaparin in preventing VTE in patients undergoing THR or TKR.