Accuracy of a Single, Heparin-Calibrated Anti-Xa Assay for the Measurement of Rivaroxaban, Apixaban, and Edoxaban Drug Concentrations: A Prospective Cross-Sectional Study

Tamana Meihandoest; Jan-Dirk Studt; Adriana Mendez; Lorenzo Alberio; Pierre Fontana; Walter A Wuillemin; Adrian Schmidt; Lukas Graf; Bernhard Gerber; Ursula Amstutz; Cedric Bovet; Thomas C Sauter; Lars M Asmis; Michael Nagler

doi:10.3389/fcvm.2022.817826

Accuracy of a Single, Heparin-Calibrated Anti-Xa Assay for the Measurement of Rivaroxaban, Apixaban, and Edoxaban Drug Concentrations: A Prospective Cross-Sectional Study

Front Cardiovasc Med. 2022 Mar 17:9:817826. doi: 10.3389/fcvm.2022.817826. eCollection 2022.

Authors

Tamana Meihandoest^{1

2}, Jan-Dirk Studt^{3

4}, Adriana Mendez⁵, Lorenzo Alberio⁶, Pierre Fontana⁷, Walter A Wuillemin⁸, Adrian Schmidt⁹, Lukas Graf¹⁰, Bernhard Gerber^{11

4}, Ursula Amstutz², Cedric Bovet², Thomas C Sauter¹², Lars M Asmis¹³, Michael Nagler²

Affiliations

¹ Department of Epidemiology, Maastricht University, Maastricht, Netherlands.
² Department of Clinical Chemistry, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.
³ Department of Medical Oncology and Hematology, University Hospital Zurich, Zurich, Switzerland.
⁴ University of Zurich, Zurich, Switzerland.
⁵ Institute for Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland.
⁶ Service and Central Laboratory of Hematology, CHUV, Lausanne University Hospital, Lausanne, Switzerland.
⁷ Division of Angiology and Hemostasis, Geneva University Hospitals, Geneva, Switzerland.
⁸ Division of Hematology and Central Hematology Laboratory, Cantonal Hospital of Lucerne and University of Bern, Bern, Switzerland.
⁹ Institute of Laboratory Medicine and Clinic of Medical Oncology and Hematology, City Hospital Zurich, Zurich, Switzerland.
¹⁰ Center for Laboratory Medicine, St. Gallen, Switzerland.
¹¹ Clinic of Hematology, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland.
¹² Department of Emergency Medicine, Inselspital, Bern University Hospital, Bern, Switzerland.
¹³ Centre for Perioperative Thrombosis and Haemostasis, Zurich, Switzerland.

Abstract

Background: Applying a single anti-Xa assay, calibrated to unfractionated heparin to measure rivaroxaban, apixaban, and edoxaban would simplify laboratory procedures and save healthcare costs.

Aim: We hypothesized that a heparin-calibrated anti-Xa assay would accurately measure rivaroxaban, apixaban, and edoxaban drug concentrations and correctly predict clinically relevant drug levels.

Methods: This analysis is part of the Simple-Xa study, a prospective multicenter cross-sectional study conducted in clinical practice. Patients treated with rivaroxaban, apixaban, or edoxaban were included. Anti-Xa activity was measured using the Siemens INNOVANCE^® Heparin assay. Drug concentrations were determined using ultra-high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cut-off levels were determined in a derivation dataset (50% of patients) and sensitivities and specificities were calculated in a verification dataset (50% of patients).

Results: Overall, 845 patients were available for analysis. Correlation coefficients (r _s ) between the heparin-calibrated anti-Xa assay and drug concentrations were 0.97 (95% CI 0.97, 0.98) for rivaroxaban, 0.96 (0.96, 0.97) for apixaban, and 0.96 (0.94, 0.99) for edoxaban. The area under the receiver operating characteristics curve (ROC) was 0.99 for all clinically relevant drug concentrations. In the verification dataset, the sensitivity was 94.2% (95% CI 90.8-96.6) for 30 μg L^-1, 95.8% (92.4-98.0) for 50 μg L^-1, and 98.7% (95.5-99.9) for 100 μg L^-1. Specificities were 86.3% (79.2-91.7), 89.8% (84.5-93.7), and 88.7% (84.2-92.2), respectively.

Conclusion: In a large prospective study in clinical practice, a strong correlation of heparin-calibrated anti-Xa measurements with LC-MS/MS results was observed and clinically relevant drug concentrations were predicted correctly.

Keywords: anti-Xa assay; diagnostic accuracy; direct oral anticoagulants; laboratory monitoring; rivaroxaban.