PB1079 - Effect of anti -factor Xa direct oral anticoagulants (DOACs) on viscoelasticity measurements in External Quality Assessment (EQA) samples: UK NEQAS BC experience

Background: UK National External Quality Assurance Scheme for Blood Coagulation (UK NEQAS BC) have provided EQA samples for Rotem and TEG testing since 2014 and for the newer cartridge-based system Rotem Sigma and TEG6 since 2019. Over this time, we have circulated samples covering normal, heparinised and more recently samples containing the DOACs edoxaban, rivaroxaban and apixaban.

Aims: To assess the effect of FX DOACs upon viscoelastic testing using EQA materials

Methods: A lyophilised sample is distributed together with a pre measured volume of distilled water and a disposable pipette in order to reconstitute the sample, and full instructions of how to process these samples. We require users to test for 30 minutes and record the CT (for Rotem devices) and R time ( for TEG devices). We also ask users to supply a comment as to whether the values obtained would be normal or prolonged, and for the heparin component whether they consider the sample to have heparin present. Data is analysed to provide median values, %CV and range of results for all parameters and acceptable limits are set around the median.

Results: Results for Rotem devices are shown in table 1 and TEG devices in table 2 together with a mean of 3 normal samples also distributed through the EQA programme.

Conclusion(s): Results for all 3 DOACs tested here show some degree of prolongation of the CT and R times seen across all platforms. The interpretations of these results was considered “prolonged” and “not due to heparin present” in 68% or more with some tests and samples where all centres that provided an interpretation were in agreement (100%). however some centres did not indicate this prolongation,. Our data shows that EQA is an essential aspect of these point of care tests.