Safety of fondaparinux for prevention of postoperative venous thromboembolism in urological malignancy: A prospective randomized clinical trial.

Objectives To prospectively evaluate the safety of postoperative fondaparinux in comparison with low molecular weight heparin in patients undergoing uro-oncological surgery. Methods The present study was a prospective, single-blind, non-inferiority randomized trial. A total of 359 patients undergoing surgery for urological malignancy were enrolled from January 2011 to December 2012. A total of 298 of these patients (fondaparinux group, 152; low molecular weight heparin group, 146) were evaluable for the intention-to-treat-analysis. Patients were randomly assigned to low-dose unfractionated heparin, 5000 units twice daily until postoperative day 1 plus either fondaparinux 2.5 mg once daily or low molecular weight heparin 2000 units twice daily until postoperative day 5. The primary end-point was postoperative bleeding as by independent review, and the study was powered to show the non-inferiority of fondaparinux versus low molecular weight heparin. The other adverse events were evaluated. D-dimer and soluble fibrin monomer complex levels were measured perioperatively. Results Bleeding occurred in 21 patients (12 in the fondaparinux group and 9 in low molecular weight heparin group, respectively). No significant differences were detected in the incidence of postoperative bleeding and the other adverse events between the two groups. The D-dimer was elevated on postoperative day 1 in one patient (16.6 μg/mL). In another patient, the soluble fibrin monomer complex was elevated (109 μg/mL). Conclusions Fondaparinux is non-inferior to low molecular weight heparin with respect to risk of bleeding. The favorable safety profile of fondparinux supports its prophylactic use as an alternative to low molecular weight heparin after surgery for urological malignancy.