Longterm anticoagulation is preferable for patients with antiphospholipid antibody syndrome. result of a decision analysis.
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OBJECTIVE: Patients with antiphospholipid antibody syndrome (APS) have a high risk for rethrombosis. Anticoagulation with warfarin and aspirin reduces the frequency of recurrences. No universally accepted approach regarding the duration and intensity of antithrombotic therapy exists. We investigated the best antithrombotic regimen for patients with APS after the first deep venous thrombosis (DVT). METHODS: We identified 6 anticoagulation regimens used in such patients, the rates of morbidity and mortality associated with bleeding, and the rates of recurrent thrombosis associated with APS by literature search. A decision tree was developed and the expected risks and benefits of each anticoagulation regimen were assessed at 2 different time points: at one year and again 4 years after the initial thrombosis. RESULTS: Based on the decision analysis, longterm warfarin alone at an international normalization ratio (INR) between 3.0 and 4.0 had the highest expected utility of the 6 antithrombotic regimens, both one year and 4 years after the initial venous thrombotic event. Short term anticoagulation for only 6 months is less beneficial. Combination therapy of warfarin and aspirin (ASA) does not offer an improvement in the expected utility over warfarin alone. CONCLUSION: Although the applicability of this analysis to clinical decision-making is not entirely clear, patients with APS presenting with DVT appear to benefit from longterm warfarin (INR 3.0-4.0) that may be superior to warfarin (INR 2.0-3.0). Short term warfarin therapy seems to be less beneficial and the use of ASA does not offer a clear additional benefit. Randomized controlled trials are needed to provide a better basis for recommendations for the treatment APS.
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