Comparative efficacy of low-molecular-weight heparins in orthopedic surgery

The low-molecular-weight heparins (LMWHs) have been evaluated in the prevention of postoperative thromboembolic disease and have been found to be clinically efficacious and safe. Studies conducted in similar surgery settings have resulted in significantly different reductions in the incidence of deep-vein thrombosis, making an analysis of grouped studies complex. Only two studies have reported head-to-head comparisons of two different LMWHs and showed no difference in clinical end points between enoxaparin and either reviparin or tinzaparin. Our study at the Aalborg hospital in Denmark, comparing two different dosage regimens of LMWH tinzaparin, supported the conclusions of the head-to-head comparative studies. LMWHs are distinct drug entities that cannot be interchanged at equivalent anti-Xa dosages, and the interpretation of their relative efficacy and safety may be biased by the degree of clinical experience of the individual investigators.