Interference of lupus anticoagulants in prothrombin time assays: implications for selection of adequate methods to optimize the management of thrombosis in the antiphospholipid-antibody syndrome.

Background And Objective: Prolonged anticoagulation aiming at International Normalized Ratio (INR) values > 3.0 has been recommended for patients with thrombosis and the antiphospholipid-antibody syndrome. We evaluated the influence of anticoagulant antibodies in two different prothrombin time (PT) assays carried out on plasma from lupus anticoagulant patients on oral anticoagulation.