The design of venous thromboembolism prophylaxis trials: fondaparinux is definitely more effective than enoxaparin in orthopaedic surgery

The fondaparinux trials in venous thromboembolism (VTE) prevention after orthopaedic surgery have been subject to methodological criticisms recently summarised in this journal. These criticisms merit comments and corrections. Fondaparinux reduced the risk of VTE and of proximal deep-vein thrombosis by more than 55% compared with enoxaparin, based on the efficacy endpoint that supported the registration and use of low-molecular-weight heparins (LMWH) in all their prophylactic indications, an endpoint endorsed by international consensus statements and health authorities. Fondaparinux is the only antithrombotic agent that significantly reduced the rate of symptomatic VTE in a single orthopaedic surgery trial that was powered to detect this effect. In contrast to the paucity of data available on LMWH, the relationship between the timing of first administration and efficacy and safety has been well documented for fondaparinux. Fondaparinux used according to its approved regimen provides a simple, easy-to-use, effective and safe post-operative regimen for all orthopaedic surgery patients.