Robert C Gosselin1, Dorothy M Adcock Funk, J Michael Taylor, Suzanne J Francart, Emily M Hawes, Kenneth D Friedman, Stephan Moll. 1. From the Department of Pathology and Laboratory Medicine, University of California, Davis Health System, Sacramento (Mr Gosselin); Colorado Coagulation, Corporation of America Holdings, Englewood (Dr Funk and Mr Taylor); the Departments of Pharmacy (Drs Francart, Hawes, and Moll) and Family Medicine (Dr Hawes) and the Hemophilia and Thrombosis Center (Dr Moll), University of North Carolina, Chapel Hill, NC; and the Hemostasis Reference Laboratory, Blood Center of Wisconsin, Milwaukee (Dr Friedman).
Abstract
CONTEXT: Rivaroxaban is a new oral anticoagulant that functions as a direct anti-Xa inhibitor. Although routine monitoring is not required, measurement of plasma concentrations may be necessary in certain clinical situations. Routine coagulation assays, such as the prothrombin time and, to a lesser degree, activated partial thromboplastin time, correlate with drug concentration, but because of reagent variability, these methods are not reliable for determining rivaroxaban anticoagulation. OBJECTIVE: To compare different methods and calibrators for measuring rivaroxaban, including the chromogenic anti-Xa assay, which, when calibrated with a rivaroxaban standard, may be more appropriate for determining anticoagulation. DESIGN: We compared measured rivaroxaban concentrations with the same anti-Xa kit but used different calibrators, with different anti-Xa kits but the same calibrators, with antithrombin-supplemented anti-Xa kit versus nonsupplemented kits, and with 2 methods based on rivaroxaban-calibrated, high-phospholipid, dilute Russell viper venom time. Regression and paired t test statistics were used to determine correlation and significant differences among methods and calibrator sources. RESULTS: Although there was strong correlation, statistically significant biases existed among methods that report rivaroxaban levels. A single-source calibrator did not alleviate those differences among methods. High-phospholipid Russell viper venom reagents correlated with rivaroxaban concentration but were not better than chromogenic anti-Xa methods. CONCLUSIONS: Rivaroxaban-calibrated, anti-Xa measurements correlate well, but the clinical significance of the variation with rivaroxaban measurements is uncertain. The antithrombin-supplemented, anti-Xa method should be avoided for measuring rivaroxaban.
CONTEXT: Rivaroxaban is a new oral anticoagulant that functions as a direct anti-Xa inhibitor. Although routine monitoring is not required, measurement of plasma concentrations may be necessary in certain clinical situations. Routine coagulation assays, such as the prothrombin time and, to a lesser degree, activated partial thromboplastin time, correlate with drug concentration, but because of reagent variability, these methods are not reliable for determining rivaroxaban anticoagulation. OBJECTIVE: To compare different methods and calibrators for measuring rivaroxaban, including the chromogenic anti-Xa assay, which, when calibrated with a rivaroxaban standard, may be more appropriate for determining anticoagulation. DESIGN: We compared measured rivaroxaban concentrations with the same anti-Xa kit but used different calibrators, with different anti-Xa kits but the same calibrators, with antithrombin-supplemented anti-Xa kit versus nonsupplemented kits, and with 2 methods based on rivaroxaban-calibrated, high-phospholipid, dilute Russell viper venom time. Regression and paired t test statistics were used to determine correlation and significant differences among methods and calibrator sources. RESULTS: Although there was strong correlation, statistically significant biases existed among methods that report rivaroxaban levels. A single-source calibrator did not alleviate those differences among methods. High-phospholipid Russell viper venom reagents correlated with rivaroxaban concentration but were not better than chromogenic anti-Xa methods. CONCLUSIONS:Rivaroxaban-calibrated, anti-Xa measurements correlate well, but the clinical significance of the variation with rivaroxaban measurements is uncertain. The antithrombin-supplemented, anti-Xa method should be avoided for measuring rivaroxaban.
Authors: Priscilla Bento Matos Derogis; Livia Rentas Sanches; Valdir Fernandes de Aranda; Marjorie Paris Colombini; Cristóvão Luis Pitangueira Mangueira; Marcelo Katz; Adriana Caschera Leme Faulhaber; Claudio Ernesto Albers Mendes; Carlos Eduardo Dos Santos Ferreira; Carolina Nunes França; João Carlos de Campos Guerra Journal: PLoS One Date: 2017-02-07 Impact factor: 3.240
Authors: Marjorie Paris Colombini; Priscilla Bento Matos Cruz Derogis; Valdir Fernandes de Aranda; João Carlos de Campos Guerra; Nelson Hamerschlak; Cristóvão Luis Pitangueiras Mangueira Journal: Thromb J Date: 2017-08-15