PB0091 - Fast screening of direct oral factor Xa inhibitors, interferences in anti-Xa assays

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

An K. Stroobants, Dr

Clinical Chemist
Radboud Laboratory for Diagnostics, Department of Laboratory Medicine, Radboud university medical center, Nijmegen, the Netherlands
Nijmegen, Gelderland, Netherlands

Co-Author(s)

LV

Lianne Vriend

clinical chemist in training
Deventer Ziekenhuis
Deventer, Overijssel, Netherlands
IS

Ivan P. Stoffer

technician
Radboudumc
Nijmegen, Gelderland, Netherlands
TW

Taylor Wauters

student
MUMC
maastricht, Limburg, Netherlands
AV

Annette Vendel

technician
RadboudUMC
Nijmegen, Gelderland, Netherlands
DH

Dave Hellenbrand

Laboratory specialist
MUMC+
Maastricht, Limburg, Netherlands
Sanna R. Rijpma, PhD

Clinical chemist
Laboratory of Hematology, Department of Laboratory Medicine, Radboud university medical center, Nijmegen, the Netherlands
Nijmegen, Gelderland, Netherlands
Rv

Rene van Oerle

researcher
MUMC
Maastricht, Limburg, Netherlands
Yvonne Henskens

Professor of the department of clinical chemistry
MUMC+
maastricht, Limburg, Netherlands

Background: The reliability of commercially available anti-Xa assays for fast direct oral anticoagulant (DOAC) screening is crucial. Literature shows that anti-Xa assays seem to be sensitive to interfering substances. However, extensive research on the effect of hemoglobin, bilirubin, lipids and heparin on the currently used anti-Xa activity assays is limited.

Aims: The aim of this study is to determine what the influence of interfering substances are on the commonly available anti-Xa assays in laboratories.

Methods: Normal plasma pools and detergent treated plasma pools were spiked with several concentrations of rivaroxaban up to 250 ng/mL and possible interfering substances: hemoglobin (0-310 μmol/L), lipid (0-12 mmol/L), bilirubin (0-500 μmol/L), and heparin (0-1,0 IE/mL), also andexanet (100 μg/mL) was added. The aliquots of each pool were analyzed by 5 anti-Xa assays with adjacent reagents: from Werfen on the ACL-TOP350, Stago on the STA R Max, Roche on the T511 and Siemens and Hyphen on the CS2500. Results were obtained with both low molecular weight (LMWH, IU/mL) and rivaroxaban (RIV, ng/mL) anti-Xa protocols.

Results: All interfering substances show some level of interference in the anti-Xa assays. However the degree of interference strongly depends on the concentration of the interfering substance and the reagent used (Table 1). Nevertheless, heparine interference at any tested concentration in the rivaroxaban anti-Xa protocol, leads to false positive results. Addition of andexanet reversed the DOAC effect only partially in all tested settings (between 60-80% reduction of the anti-Xa activity).

Conclusion(s): Fast and reliable DOAC screening is beneficial for patients presenting with severe bleeding or thrombosis in an acute situation. This study shows that anti-Xa assays are affected by increased levels of hemoglobin, bilirubin, lipid and as expected heparin. These interfering substances need to be taken into consideration when interpreting the results when monitoring the anti-Xa activity under DOAC use.