LOW-MOLECULAR-WEIGHT HEPARINS

Low molecular weight heparins (LMWH) have been commercially available in France for several years. Their effectiveness and easier use perhaps explain why, among all European and American physicians, the French are the only ones who prefer to prescrire LMWH. In France, the preferential use of LMWH is already common practice for prevention of deep vein thrombosis (DVT) and should reach this position for the treatment of DVT in a near future. But among these practices it is necessary to distinguish those which are established on scientific grounds from those which are accepted, but not established, and those which are still unanswered clinical questions. Among the points established is the use of LMWH to prevent DVT in general and orthopaedic surgery and in medicine, and in the treatment of DVT. Among those which are generally accepted, although not fully established, are the lower haemorrhagic risk/efficiency ratio compared with standard heparin, the absence of need to measure anti Xa in prevention, the lower risk of heparin-induced thrombocytopenia, the effectiveness and absence of specific risk when used during pregnancy. The points which are not yet solved (but are becoming of common practice) are the lack of need to measure anti Xa activity, even when indicated for treatment of established DVT, and the absence of risk of osteoporosis. Among the points which are still debetable questions are the comparative efficacy of administration before or immediately after surgery (a crucial point for the management of patients receiving lumbar anaesthesia). In view of the numerous on-going clinical trials involving LMWH it is necessary to have frequent review, such as this one, to keep abreast of established data.