Abstract Number: PB0598
Meeting: ISTH 2020 Congress
Background: Direct oral anticoagulants (DOACs) have been shown to interfere with many coagulation assays. For thrombophilia investigations this might lead to falsely positive Lupus Anticoagulant (LA) results. A simple and rapid assay to rule out interfering DOACs is needed.
The MRX PT DOAC test is based on two simultaneously run prothrombin time (PT) assays, one DOAC-insensitive PT assay and one DOAC-sensitive PT assay. The INR (International Normalized Ratio) determined by the DOAC-insensitive PT assay and the DNR (DOAC Normalized Ratio) determined by the DOAC-sensitive assay will be the same for samples without DOACs, while for DOAC-containing samples there will be a difference. This difference is expressed as a clot time ratio (CTR). DOAC is present in samples with CTR greater than the reference interval.
Aims: To use MRX PT DOAC to detect interfering DOACs in samples during thrombophilia investigation.
Methods: Material leftover from 154 citrated blood samples that had undergone analysis for investigation of thrombophilia were analysed with MRX PT DOAC. LA results were obtained from the laboratory information system. MRX PT DOAC CTR reference interval was set using a reference material of 120 healthy volunteers. The study was performed according to Swedish law on biobanking and research ethics.
Results: LA was detected in 9 out of 154 patient samples. One sample was falsely LA positive, and a >CTR in the MRX PT DOAC test revealed the presence of DOAC in this sample, which was confirmed with an independent method. Seven samples were LA positive with < CTRs, i.e. MRX PT DOAC correctly cleared these samples from DOAC interference. One sample was LA positive (diluted Russel Viper Venom Time ratio, dRVVT ratio>3) with >CTR; MRX PT DOAC indicated DOAC in this sample.
Conclusions: MRX PT DOAC can detect the presence of interfering DOACs in patient samples during thrombophilia investigation.
To cite this abstract in AMA style:
Onelöv L, Abelius M, Lindahl T. The Novel Prothrombin Time (MRX PT DOAC) Assay ‐ Can Be Used to Detect Interfering DOACs in Thrombophilia Investigation [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/the-novel-prothrombin-time-mrx-pt-doac-assay-%e2%80%90-can-be-used-to-detect-interfering-doacs-in-thrombophilia-investigation/. Accessed September 29, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-novel-prothrombin-time-mrx-pt-doac-assay-%e2%80%90-can-be-used-to-detect-interfering-doacs-in-thrombophilia-investigation/