Between 16 and 30% of patients who undergo Hip-replacement surgery have a risk of developing deep-vein thrombosis (DVT)-even when anti-clotting agents such as heparin and warfarin are used. DVT from hip surgery can occasionally result in death due to pulmonary embolism (in around 0.1-0.4% of cases). Michael Rud Lassen from University Hospital Copenhagen, Hillerd, Denmark, and colleagues assessed the ability of fondaparinux, the first of a new class of synthetic antithrombotic agents, to further reduce DVT risk.
Around 2300 patients from 16 European countries who were undergoing elective hip-replacement surgery were randomly assigned to once daily injections of either 2.5 mg fondaparinux, starting postoperatively, or 40 mg of the anti-clotting agent enoxaparin, starting preoperatively. Analysis was based on the outcomes of 79% of the patients who took part in the study. By the eleventh day after surgery, venous thromboembolisms were recorded in 4% of patients assigned fondaparinux and in 9% assigned enoxaparin. The two groups did not differ in frequency of death or clinically relevant bleeding.
A second study in this weeks issue of THE LANCET by the same team of investigators (led by Alexander Turpie from Hamilton Health Sciences, Canada), compared the effects of fondaparinux with enoxaparin when either drug was given postoperatively to patients after hip-replacement surgery. 2275 patients were recruited from the USA, Canada, and Australia; there was a 26% reduction in venous thromboembolism among patients given fondaparinux which was clinically (but not statistically) significant