Abstract

The aim was to determine the validity of the international normalized ratio (INR) and prothrombin time (PT) as a monitor for warfarin therapy in patients with lupus anticoagulants and recurrent thrombosis, and to investigate alternative approaches to monitoring warfarin therapy and new treatment options in these patients. A case is described of a 63-year-old female with antiphospholipid syndrome and recurrent venous thrombosis despite optimal adjusted warfarin therapy. In patients with lupus anticoagulants, the INRs obtained while receiving warfarin vary and often overestimate the extent of anticoagulation, while PT without receiving warfarin is often prolonged. In conclusion, lupus anticoagulants can influence PT and lead to INR that does not accurately reflect the true level of anticoagulation. Optimizing of (warfarin) oral anticoagulation therapy could be achieved by individual monitoring of anticoagulation effect with a test thatis insensitive to lupus anticoagulants (chromogenic factor X assay). Emerging oral anticoagulants, direct thrombin inhibitors and direct factor Xa inhibitors, such as dabigatran and rivaroxaban, with a predictable anticoagulant response and little potential for food or drug interactions, have been designed to be administered in fixed doses without coagulation monitoring and could be the treatment choice for these patients.