Prevention of Venous Thromboembolism

Prospective clinical trials have shown that reduction in frequency of deep vein thrombosis (DVT) and pulmonary embolism (PE) can be achieved by physical preventive methods or by administration of antithrombotic drugs. There is however confusion concerning the best form of prophylaxis for different patient groups, difficulty in translating results of clinical trials directly into practice, and ignorance of the dollar cost of the various regimes. Critical analysis of the literature permits prediction of expected frequencies of fatal PE and of DVT and complications of therapy, but questions remain. The prevalence of silent PE in different populations is not established. Definition of a high risk group is imprecise, so patients at lesser risk are exposed to the side effects of antithrombotic prophylaxis with little to gain. Since the natural history of DVT is poorly understood, side effects of anticoagulant therapy are also inflicted on many with little likelihood of PE for the benefit of a few susceptible patients. Apparent differences in rate of occurrance of DVT on the two sides of the Atlantic are suggested but unproven and not explained.Despite these uncertainties, determination of cost/effectiveness of preventive programs is possible and can provide a workable guide to clinical practice.