Duration of prophylaxis against venous thromboembolism with fondaparinux after hip fracture surgery: a multicenter, randomized, placebo-controlled, double-blind study.

BACKGROUND: The benefit of thromboprophylaxis for 1 month has never been evaluated in patients undergoing hip fracture surgery, a setting in the highest risk category for postoperative venous thromboembolism (VTE).

METHODS: In a double-blind multicenter trial, 656 patients undergoing hip fracture surgery were randomly assigned to receive prophylaxis with a once-daily subcutaneous injection of either 2.5 mg of fondaparinux sodium or placebo for 19 to 23 days. Before randomization, all patients had received fondaparinux for 6 to 8 days. The primary efficacy outcome was VTE occurring during the double-blind period (deep vein thrombosis detected by mandatory bilateral venography or documented symptomatic deep vein thrombosis or pulmonary embolism). The main safety outcome was major bleeding.

RESULTS: The primary efficacy outcome was assessed in 428 patients. Fondaparinux reduced the incidence of VTE compared with placebo from 35.0% (77/220) to 1.4% (3/208), with a relative reduction in risk of 95.9% (95% confidence interval, 87.2%-99.7%; P<.001). Similarly, the incidence of symptomatic VTE was significantly lower with fondaparinux (1/326; 0.3%) than with placebo (9/330; 2.7%). The relative reduction in risk was 88.8% (P =.02). Although there was a trend toward more major bleeding in the fondaparinux group than in the placebo group (P =.06), there were no differences between the 2 groups in the incidence of clinically relevant bleeding (leading to death, reoperation, or critical organ bleeding).

CONCLUSIONS: Extended prophylaxis with fondaparinux for 3 weeks after hip fracture surgery reduced the risk of VTE by 96% and was well tolerated.