WEDNESDAY, June 25 (HealthDay News) -- Extended use of the oral drug rivaroxaban helps prevent potentially fatal blood clots after hip replacement surgery, British researchers say.

The risk of venous thromboembolism (VTE) is high after total hip replacement, and the risk can persist after a patient leaves the hospital. Current guidelines recommend patients receive a heparin-based preventive drug such as enoxaparin (Lovenox) for a minimum of 10 days, and up to 35 days, after surgery. However, this preventive treatment is not used much after patients leave the hospital, according to background information in the study.

The researchers at the London School of Medicine and Dentistry and the Thrombosis Research Institute compared the new oral antithrombotic drug rivaroxaban (Xarelto) with enoxaparin in the treatment of hip replacement patients.

In the randomized, controlled trial, 1,252 patients received 10 milligrams of oral rivaroxaban once daily for 31 to 39 days, followed by placebo injection for 10 to 14 days, while 1,257 patients received 40 milligram once-daily injections of enoxaparin for 10 to 14 days, followed by placebo tablets for 31 to 39 days.

The completed analysis of 864 patients in the rivaroxaban group and 869 patients in the enoxaparin group found that patients in the enoxaparin group were more than four times as likely to suffer deep vein thrombosis, nonfatal pulmonary embolism, or die than patients in the rivaroxaban group -- 9.3 percent versus 2 percent. Both groups had similar rates of bleeding events during treatment.

"Extended thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin plus placebo for the prevention of venous thromboembolism, including symptomatic events, in patients undergoing total hip arthroplasty [replacement]," the researchers concluded.

The study was released online Wednesday by The Lancet and will be published in an upcoming issue.

"With superior efficacy, no compromise in safety, and a convenient once-daily regimen, rivaroxaban seems an obvious choice for simplified thromboprophylaxis after hip or knee arthroplasty [replacement]," Dr. John Eikelboom and Jeffrey Weitz, of McMaster University in Hamilton, Ontario, Canada, wrote in an accompanying editorial.

More information

The American Academy of Orthopaedic Surgeons has more about total hip replacement.