Direct oral anticoagulants – new challenge for laboratory medicine

Abstract

A new generation of oral anticoagulants, direct thrombin or activated factor X inhibitors gradually replaces the existing antithrombotic agents, administered parenterally (heparin) or orally (vitamin K antagonists). Currently, the most widely used class of direct oral anticoagulants (DOACs) are the direct thrombin inhibitor dabigatran and rivaroxaban, apixaban and edoxaban – Xa inhibitors. Although previous reports suggested that DOACs therapy does not require laboratory screening, recently the new indications for monitoring and the types of laboratory tests used in the evaluation of the effectiveness of treatment have been updated. To quantify the activity of direct thrombin inhibitors a dilute thrombin clotting time (dTT) or ecarin clotting time (ECT) is recommended. The effect of rivaroxaban and apixaban can be determined by anti-Xa activity assay when calibrated with a rivaroxaban and apixaban standard. Observed changes in routine coagulation tests such as activated partial thromboplastin time (APTT), and prothrombin time (PT), with varying degrees of severity, can only be an indicator of an additional screening, which is the emergency clinical interventions.