The results of three studies could usher in a new era of fixed-dose oral thromboprophylaxis.

Summary

Prophylactic anticoagulation is recommended practice following total knee and hip arthroplasty. Commonly used thromboprophylaxis agents include warfarin, which requires frequent monitoring, and subcutaneous low-molecular-weight heparins such as enoxaparin, which are cost-effective only if patients or their caregivers can inject the drug. In three recent manufacturer-funded trials, oral rivaroxaban (a highly selective direct factor Xa inhibitor that is prescribed at a fixed dose and does not require monitoring) was compared with subcutaneous enoxaparin for thromboprophylaxis after total knee and hip arthroplasty.

In one trial, investigators randomized 2531 patients who underwent knee arthroplasty to daily oral rivaroxaban or subcutaneous enoxaparin for 10 to 14 days. The primary outcome, a composite of any deep venous thrombosis, nonfatal pulmonary embolism, or death within 13 to 17 days after surgery, occurred in 9.6% of patients who received rivaroxaban and in 18.9% of patients who received enoxaparin (P<0.001). No difference in major bleeding or other adverse events was observed between the groups.

In another trial, investigators randomized 2509 patients who underwent hip arthroplasty to daily oral rivaroxaban for 31 to 39 days or subcutaneous enoxaparin for 10 to 14 days. The primary outcome, a composite of any deep venous thrombosis, nonfatal pulmonary embolism, or death within 42 days after surgery, occurred in 2.0% of rivaroxaban patients and in 9.3% of enoxaparin patients (P<0.001). The incidence of bleeding was similar in the groups.

In a similar trial, investigators randomized 4541 patients who underwent hip arthroplasty to daily oral rivaroxaban or subcutaneous enoxaparin for 35 days. The primary outcome, a composite of any deep venous thrombosis, nonfatal pulmonary embolism, or death within 36 days after surgery, occurred in 1.1% of rivaroxaban patients and in 3.7% of enoxaparin patients (P<0.001). No difference in major bleeding or other adverse events was noted between the groups.

Comment

Once-daily oral rivaroxaban is superior to once-daily subcutaneous enoxaparin in preventing venous thromboembolism and death after total hip and knee arthroplasty. In addition, the two drugs have similar safety profiles. These findings could usher in a new era of fixed-dose oral thromboprophylaxis that does not require monitoring or injection and that likely will be more acceptable to patients than thromboprophylaxis with warfarin or subcutaneous low-molecular-weight heparins. Rivaroxaban is not yet approved for use in the U.S.

— Paul S. Mueller, MD, MPH, FACP

Technorati Tags: Articulating Joints, hip implant, Hip Replacement, Hip Revision, joint disease, joint replacement, Knee replacements, orthopaedic implants, risk factors, surgery, surgical safety, Rivaroxaban, Enoxaparin, anticoagulant, warfarin

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