A randomized controlled study evaluating the safety and efficacy of different low molecular weight heparins for 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 (D VT) as unfractionated heparin. However, different LMWHs vary significantly in their pharmacokinetic profile and bioavailability pattern. It remains un known, whether these pharmacological differences result in a clinically div ergent behavior. Methods: Safety and antithrombotic efficacy of three LMWHs, certoparin (18 mg), dalteparin (30 mg) and enoxaparin (24 mg), were compared in a prospect ive, randomized controlled trial involving 188 patients undergoing knee or hip replacement or spinal surgery. Efficacy was assessed by changes in veno us flow patterns between pre- and postoperative Doppler sonography. The cli nical endpoint for the assessment of safety were intra- and postoperative b leeding, changes in activated partial thromboplastin time (APTT) and thromb in 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. I n 21 patients (11.2%) local hematoma or local infections complicated the po stoperative course. Of these 21 patients, 13 belonged to the certoparin gro up, 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 blee ding, APTT, TCT and blood count. Conclusion: The results of this study suggest, that all three LMWHs are equ ally efficacious in the prophylaxis of DVT in high risk patients after orth opedic surgery. Larger randomized controlled trials are necessary to confir m this conclusion and to evaluate the clinical relevance of the observed di fferences in postoperative complications.