PB0117 - Nordic Biomarker MRX PT DOAC assay on Sysmex CN6000 Analysers

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Jackie Dobson-Storr

Senior Biomedical Scientist
Northern General Hospital, Sheffield.
Sheffield, England, United Kingdom

Co-Author(s)

Lee J. Beckett, MSc

Routine Coagulation Scientific Lead
Northern General Hospital
Sheffield, England, United Kingdom
EB

Emma Broomhead

Senior Biomedical Scientist
Northern General Hospital, Sheffield.
Sheffield, England, United Kingdom
MC

Mark Crowther

Professor
Department of Medicine, McMaster University
Hamilton, Ontario, Canada
SM

Siraj Mithoowani

Assistant Professor, Dept of Medicine
MCMaster University
Hamilton, Ontario, Canada
Bs

Brittany Margaret-Anne salter

Haematology Resident
Dept Medicine, McMaster University
Hamilton, Ontario, Canada
KM

Karen Moffat

Technical Specialist, Coagulation
Hamilton Regional Laboratory Medicine Program
Hamilton, Ontario, Canada
SC

Stephen Carlino

Hamilton Regional Laboratory Medicine Program
Hamilton Regional Laboratory Medicine Program
Hamilton, Ontario, Canada
LO

Liselotte Onelov

Study Manager
Nordic Biomarker
Umea, Vasterbottens Lan, Sweden

Background: The MRX PT DOAC assay measures the effect of Direct Oral Anticoagulants (DOACs) using a single reagent. The test is simple, rapid and can detect the presence of Rivaroxaban, Apixaban, Edoxaban and Dabigatran. It is based on a DOAC-insensitive and a DOAC-sensitive Prothrombin Time (PT), the results of which are used to calculate the Clot Time Ratio (CTR). The CTR is used to determine whether a DOAC is present in a patient sample.

Aims: To assess the sensitivity and specificity of the MRX PT DOAC assay to DOACs on Sysmex CN6000 analyser.

Methods: Testing utilised the Sysmex CN6000 analyser, calibrated using MRX PT DOAC Calibrators. The INR was generated from the insensitive assay calibration, DOAC Normalised Ratio (DNR) from the sensitive assay. The Clot Time Ratio (CTR) was then calculated DNR/INR=CTR.
Plasma samples were tested using the MRX PT DOAC assay from patients with normal clotting screens (control group) N=30, patients on Apixaban n=32, Rivaroxaban n=16, Edoxaban n=17, Warfarin n=34 and patients with Liver disease n=23.

Results: The presence of a DOAC (>50ng/ml) was indicated by a CTR of 1.31 (this was calculated from the mean CTR of the normal samples plus 2xSD). There were no false negatives (normal CTR in the presence of DOAC >50 ng/ml) in rivaroxaban and edoxaban groups and 3 false negative Apixaban samples.
Table 1 shows the assay Sensitivity and Specificity and the Negative Predictive Value (NPV)/Positive Predictive Value (PPV).

Conclusion(s): The MRX PT DOAC is suitable to screen for the presence of Apixaban, Rivaroxaban and Edoxaban given its high sensitivity and specificity, and clinically relevant PPV and NPV. These findings suggest further study is warranted, as, if validated, they suggest this assay may be useful in decision-making around use of reversal agents in patients with bleeding or need for urgent surgery while taking a DOAC.