O1067 INFLUENCE OF THE DURATION OF FONDAPARINUX PROPHYLAXIS IN PREVENTING VENOUS THROMBOEMBOLISM FOLLOWING HIP FRACTURE SURGERY

Abstract

Aims: In orthopedic surgery, the optimal duration of thromboprophylaxis is debated, and very few data are available in hip fracture. We addressed these issues in 5 randomized double-blind clinical trials of fondaparinux. Methods: In four studies in 7344 orthopedic surgery patients, fondaparinux was administered up to 11 days and compared to approved enoxaparin regimens. In the PENTHIFRA-Plus study in 656 hip fracture surgery patients, after an initial treatment with fondaparinux for 7±1 days, patients were randomized to fondaparinux or placebo for additional 21±2 days. In all trials, primary efficacy was venous thromboembolism (VTE), at the end of the treatment period. Results: In the four 11-day prophylaxis studies, fondaparinux reduced the incidence of VTE from 13.7% with enoxaparin to 6.8% (risk reduction [RR]: 55.2%; P< 0.001). Fondaparinux efficacy was significantly influenced by treatment duration (P< 0.001): for instance, the incidence of VTE was lower in patients treated for 9 to11 days (5.2%) than in patients treated for ≤5 days (8.7%, P= 0.038). In the PENTHIFRA-Plus study, the incidence of VTE up to 4 weeks was reduced to 1.4% compared with 35.0% with placebo (relative RR: 95.9%, P< 0.001). The incidence of symptomatic VTE was also significantly lower with fondaparinux (0.3%) than with placebo (2.7%, relative RR: 88.8%, P=0.021). Conclusions: Fondaparinux efficacy in preventing VTE in orthopedic surgery increased significantly with a longer duration of treatment. Hip fracture surgery patients are at high risk of VTE up to 4 weeks after surgery and treatment with fondaparinux for 4 weeks postoperatively provides greater benefit than active treatment for only 1 week.