The distribution of anti-factor Xa activity value, PT and APTT at peak and trough times in patients with direct anti-factor Xa inhibitors

Background Although patients taking direct oral anticoagulants (DOACs) do not require routine coagulation monitoring, the distribution of anti-factor Xa activity (AXA) values, prothrombin time (PT), PT-international normalized ratio (INR) and activated partial thromboplastin time (APTT) in patients on apixaban, edoxaban and rivaroxaban therapy is still not clear. Purpose The aim is to set the standard values of AXA values, PT, PT-INR and APTT in patients using DOACs. Methods We measured AXA, using chromogenic assay with the HemosIL Liquid Heparin kit, PT, PT-INR and APTT at trough and peak times in 224 patients with non-valvular atrial fibrillation and venous thromboembolism, of whom 90 received apixaban, 100 received edoxaban and 34 received rivaroxaban. The peak time was defined as 3 hours after the intake of apixaban or rivaroxaban, and 2 hours after the intake of edoxaban. The trough time was defined as that immediately before the intake. The AXA values, PT, PT-INR and APTT were measured at least 72 hours after the start of treatment. The dosage of DOACs is defined according to the prescribing information in Japan. Results (The order of results below is apixaban, edoxaban and rivaroxaban, respectively.) The average AXA values were 2.29, 0.23 and 0.39 (IU/mL) at trough time, and 3.04, 1.01 and 1.70 (IU/mL) at peak time. The average PT values were 17.9, 12.9 and 13.1 (s) at trough time, and 19.7, 15.5 and 17.5 (s) at peak time. The average PT-INR values were 1.49, 1.07 and 1.08 at trough time, and 1.65, 1.29 and 1.45 at peak time. The average APPT values were 34.5, 31.3 and 32.0 (s) at trough time, and 39.5, 35.9 and 39.8 (s) at peak time. Conclusion Our findings reveal the standard values of AXA, PT, PT-INR and APTT in patients using apixaban, edoxaban and rivaroxaban in each dosage. The DOACs should be changed if the measured value is out of those standard values in 90% confidence interval. Funding Acknowledgement Type of funding source: None