Fondaparinux compared with enoxaparin for the prevention of venous thromboembolism after hip-fracture surgery.

Background: Surgery for hip fracture carries a high risk of venous thromboembolism, despite the use of current thromboprophylactic treatments. Fondaparinux, a synthetic pentasaccharide, is a new antithrombotic agent that may reduce this risk. Methods: In a double-blind study, we randomly assigned 1711 consecutive patients undergoing surgery for fracture of the upper third of the femur to receive subcutaneous doses of either 2.5 mg of fondaparinux once daily, initiated postoperatively, or 40 mg of enoxaparin once daily, initiated preoperatively, for at least five days. The primary efficacy outcome was venous thromboembolism up to postoperative day 11. Venous thromboembolism was defined as deep-vein thrombosis detected by mandatory bilateral venography, documented symptomatic deep-vein thrombosis, or documented symptomatic pulmonary embolism. The main safety outcomes were major bleeding and mortality from all causes. The duration of follow-up was six weeks. Results: The incidence of venous thromboembolism by day 11 was 8.3 percent (52 of 626 patients) in the fondaparinux group and 19.1 percent (119 of 624 patients) in the enoxaparin group (P<0.001). The reduction in risk with fondaparinux was 56.4 percent (95 percent confidence interval, 39.0 to 70.3 percent). There were no significant differences between the two groups in the incidence of death or clinically relevant bleeding. Conclusions: In patients undergoing surgery for hip fracture, fondaparinux was more effective than enoxaparin in preventing venous thromboembolism and was equally safe. (N Engl J Med 2001;345:1298-304.) Copyright (C) 2001 Massachusetts Medical Society.