Preventing thromboembolism after joint surgery just got easier

Rivaroxaban is a new anticoagulant that inhibits activated factor X or thrombin⇑. It acts fast, produces predictable anticoagulation, and can be taken by mouth just once a day. Could rivaroxaban be used to give extended protection from venous thromboembolism after joint replacement surgery? A series of three trials suggests it works better than enoxaparin, an injectable low molecular weight heparin, as both short term and extended prophylaxis.

The first head to head trial compared five weeks of rivaroxaban 10 mg with five weeks of enoxaparin 40 mg in adults having hip replacement surgery. The new pill reduced the risk of deep vein thrombosis, non-fatal pulmonary embolism, or death from any cause by 70% (1.1% v 3.7%; relative risk reduction 70%, 95% CI, 49% to 82%). In a second trial using the same outcome, a shorter course of rivaroxaban (10-14 days) worked significantly better than a shorter course of enoxaparin in adults having knee replacement surgery (relative risk reduction, 49%, 35% to 61%). The third trial compared long term rivaroxaban (31-39 days) with shorter term enoxaparin (10-14 days) in adults having hip replacement surgery. Only 2% of patients given the new drug for a longer period either died or had a deep vein thrombosis or non-fatal pulmonary embolism, compared with just over 9% of controls (relative risk reduction 79%, P<0.001).

In all three trials, rivaroxaban also reduced the risk of major thromboembolism, defined as proximal deep vein thrombosis, non-fatal pulmonary embolism, or death related to venous thromboembolism. None reported excess bleeding associated with the new drug. Industry sponsors Bayer HealthCare and Johnson & Johnson Pharmaceuticals analysed the data.

Current guidelines already recommend extended prophylaxis after joint replacement surgery, but it has been hard to achieve with heparins, which must be injected, or warfarin, which must be monitored. Rivaroxaban and …