Haemorrhagic and thromboembolic complications versus intensity of treatment of venous thromboembolism with oral anticoagulants.

In order to assess the recommended therapeutic interval with the prothrombin complex analysis, using Stago Prothrombin-complex Assay (SPA) as the reagent, a retrospective multicentre study was performed to obtain clinical documentation. All thromboembolic and haemorrhagic complications during secondary prophylaxis after venous thromboembolism in 272 patients were recorded and related to the intensity of the oral anticoagulation. Six thromboembolic complications in patients without a malignant disease occurred at SPA levels greater than or equal to 28%, confirming that the limit of the therapeutic range, determined by the risk of thromboembolic recurrences, should be set at an SPA level of 25% (international normalized ratio, INR = 2.0), at least in venous disease. Major haemorrhages occurred mainly at SPA levels less than 10% (INR greater than 4.0), unless underlying risk factors were present, thus setting the other limit of the therapeutic range. However, an adjustment of this limit to SPA = 15% (INR approximately 3.0) is suggested, since it would lead to further reduction of haemorrhage and is advisable in most patients with venous thromboembolism.