ROLE OF LOW-MOLECULAR-WEIGHT HEPARINS IN THE PREVENTION AND TREATMENTOF VENOUS THROMBOEMBOLISM AFTER SURGERY

Objective: To examine the effectiveness of low molecular weight hepari ns (LMWHs) in the prevention and treatment of deep venous thrombosis ( DVT) and pulmonary embolism (PE) following surgery. Design: A review o f the results of randomized controlled trials of LMWHs in which LMWH w as compared with placebo, dextran or unfractionated heparin. Methods: Published data from journals indexed in Index Medicus (Medline CD Rom) since 1984 or found in the reference lists of such journals. Main out come measures: Incidence of DVT as assessed by isotope scanning and/or venography and the incidence of PE and bleeding complications. Result s: Prophylaxis with LMWH causes a significant reduction in the inciden ce of DVT compared with placebo, dextran and unfractionated heparin in high-risk patients undergoing orthopaedic operations, but there is no conclusive evidence that they are better than unfractionated heparin in general surgery. There was inconclusive evidence that LMWHs reduced the incidence of PE compared with dextran or unfractionated heparin. LMWHs were at least as safe as unfractionated heparin in terms of majo r haemorrhage or postoperative blood loss. Conclusions: Current eviden ce suggests the use of LMWHs in high-risk orthopaedic patients as a me ans of thromboprophylaxis is cost-effective. More trials are necessary to justify the use of LMWHs over unfractionated heparin in general su rgery.