Background: The knowledge of the impact of direct oral anticoagulants (DOACs) on hemostasis diagnostic tests is a clinical need. The regulatory documents provide some information but are generally limited to the most common hemostasis assays and guidance are not available to explain how to deal with all these interferences.

Aims: To provide an in-depth overview on the impact of DOACs on a series of hemostasis diagnostic tests. The final goal is to provide biologists and clinicians with practical recommendations for thrombophilia testing.

Methods: Results were obtained from the compilation of our series of investigation addressing the impact of DOACs (i.e. apixaban, betrixaban, dabigatran, edoxaban, rivaroxaban) on routine and thrombophilia testing. This was completed by a review of the literature.

Results: Overall, factors Xa and factors IIa inhibitors affect clot-based hemostasis diagnostic tests resulting in false-positive or false-negative results, even at low concentrations obtained with a 24-hours wash-out (►Figure 1 & 2).

An effect on thrombin-based hemostasis diagnostic tests is observed with dabigatran but not with anti-Xa and vice-versa. No impact was observed with antigenic or chromogenic methods for the assessment of protein S and C activity.

Conclusions: Current routine coagulation tests as well as hemostasis diagnostic tests are in most cases impaired by DOACs potentially leading to incorrect clinical decision making. Overall, chronometric and chromogenic tests requiring factor Xa and/or factor IIa are impacted by DOACs with an inter-reagent variability and concentration-dependently. Indeed, some reagents (e.g. Dade^®Innovin^® until 100ng/mL) are less sensitive to DOACs and could be proposed in their presence. The use of a devices or chemical compounds able to remove DOACs is still under-investigation but seems to be a cheaper promising solution, even for high concentration of DOACs. Antagonizing the anticoagulant could be interesting but with a higher cost. The development of new diagnostic tests insensitive to DOACs should also be considered.

[Figure 1: Impact of factor Xa inhibitors related to indications on diagnostic assays.]

[Figure 2 : Summary of recommended assays for the measurement of direct oral anticoagulants in plasma]

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/impact-of-doacs-on-hemostasis-diagnostic-tests-practical-recommendations-and-guidance-for-the-laboratory/