PROPHYLACTIC TREATMENT OF POSTOPERATIVE DEEP VENOUS THROMBOSIS IN ORTHOPEDIC-SURGERY OF THE HIP WITH ORAL ANTICOAGULANT

There are still many problems related to the prophylaxis of post-operative deep venous thrombosis (DVT), irrespective of the methods utilized. The oral anticoagulant seem to be effective for this purpose, but in general, few patients have been included in the studies and the results are sometimes contradictory. We have therefore made a meta-analysis of all the randomized trials in which Oral Anticoagulant (OA) were compared with a Control Group without any antithrombotic therapy, assessing the incidence of post-operative DVT by a labelled fibrinogen test (LFT) or by phlebography, in orthopaedic surgery of the hip. The use of OA brought about a risk reduction of post-operative DVT amounting to 64% +/- 11:p < 0.001, a risk reduction of symptomatic pulmonary embolism of 78% +/- 21:p < 0.001, and a risk reduction of fatal pulmonary embolism of 74% +/- 18:p < 0.001, with a slight reduction of the risk of total mortality of 35% +/- 13:p < 0.01, probably explained by the old populations studied (over 70 years) and by the type of surgery studied (fracture). The risk of haemorrhagic complications on OA increased by 176% +/- 33:p < 0.001, but without any significant increase of severe haemorrhagic complications (p = 0.08). Thus, the prophylactic efficacy of the OA on post-operative DVT appears to be clearly demonstrated, but with an increased incidence of haemorrhagic complications, probably correlated to the high level of International Normalized Ratio (INR) generally obtained (assumed to be more than 3). But low doses of OA, resulting in an INR between 2 and 3, seem to be just as efficacious and less haemorrhagic in orthopaedic surgery. Therefore, it could be of interest to use OA to take over early from prophylactic heparin therapy, since the long-term incidence of post-operative DVT is not negligible in patients at risk and because of a risk of thrombocytopenia brought about by heparin. An optimum anticoagulation level should also be defined through further randomized trials (INR probably between 1.5 and 3) so as to reduce the haemorrhagic risk.