Anticoagulation variability in relation to occurrence of thromboembolism and clinically relevant bleeding in patients on warfarin monitored with either Fiix-prothrombin time or Quick-prothrombin time

Abstract

Introduction: Warfarin is challenging in use and its effect must be carefully monitored to maintain the desired anticoagulation level. The Quick prothrombin time (PT) is most commonly used to monitor the warfarin effect by measuring the effect of changes in coagulation factors (F) II, VII and X on the clotting time. Experiments suggest that rapid fluctuations in factor VII activity, mainly due to its short half-life, contribute to variation in the measured clotting time but less to the antithrombotic effect itself. The newly developed Fiix prothrombin time (Fiix-PT) is only sensitive to factors II and X and has been shown to improve anticoagulation stability. The objective of the current study is to estimate anticoagulation variability in relation to the occurrence of thromboembolic events and bleeding in patients monitored with Fiix-PT or PT.