[Prospective Randomized Study Comparing the Effectiveness and Tolerance of Various Low-molecular-weight Heparins in High Risk Patients]

Introduction: In several studies, low-molecular-weight-heparins (LMWH) have been shown to be as effective in the prevention of deep vein thrombosis (DVT) as unfractionated heparin. However, different LMWHs vary significantly in their pharmacokinetic profile and bioavailability pattern. It remains unknown, whether these pharmacological differences result in a clinically divergent behavior.

Methods: Safety and antithrombotic efficacy of three LMWHs, certoparin (18 mg), dalteparin (30 mg) and enoxaparin (24 mg), were compared in a prospective, randomized controlled trial involving 188 patients undergoing knee or hip replacement or spinal surgery. Efficacy was assessed by changes in venous flow patterns between pre- and postoperative Doppler sonography. The clinical endpoint for the assessment of safety were intra- and postoperative bleeding, changes in activated partial thromboplastin time (APTT) and thrombin clotting time (TCT), local hematoma and local infections.

Results: Two verified DVTs (1.1%) were observed in the study, leading to no statistical difference in the antithrombotic efficacy of the used LMWHs. In 21 patients (11.2%) local hematoma or local infections complicated the postoperative course. Of these 21 patients, 13 belonged to the certoparin group, compared to 4 patients each in the other groups (p < 0.01). An allergic reaction occurred in only one case treated with dalteparin. No differences between the groups were observed in terms of intra- and postoperative bleeding, APTT, TCT and blood count.

Conclusion: The results of this study suggest, that all three LMWHs are equally efficacious in the prophylaxis of DVT in high risk patients after orthopedic surgery. Larger randomized controlled trials are necessary to confirm this conclusion and to evaluate the clinical relevance of the observed differences in postoperative complications.