OC 20.5 - Rapid detection of FXa inhibitor activity using point of care testing

Background: Drug specific assays are important to determine whether there are clinically relevant anticoagulant activity in patients on Factor Xa (FXa) inhibitors who present with major bleeding or prior to invasive procedures/surgeries.

Current laboratory assays to determine anti-Xa activity can take up to 30 minutes or longer to be resulted and are not readily accessible in many hospitals. The inability to turn around these tests rapidly can lead to delays in administering potentially life-saving treatment.

ClotPro (Haemoview Diagnostics) is a point of care (POC) diagnostic instrument that can be used by non-laboratory scientists to perform rapid tests on whole blood for the detection of FXa inhibitors. The presence of clinically relevant anticoagulant activity can be excluded within 5 minutes.

Aims: Our study aims to evaluate the reliability, correlation and comparability of the ClotPro RVV clotting time to anti-Xa activity assays performed on the Werfen ACL TOP750 automated coagulation analyser.

Methods: Anticoagulated patient samples from the South West Sydney Health District (SWSLHD) were analysed in real-time on the Werfen ACL TOP750 automated coagulation analyser and the ClotPro concurrently over a 6 month period.

Results: The average time to result for the anti-Xa assays on the Werfen ACL TOP750 was 71 minutes (range 21-202 minutes). The anti-Xa levels were compared to the clotting time (CT) on RVV-test and there was a significant and positive correlation between the anti-Xa activity and CT. The Pearson correlation coefficient was 0.86 for apixaban, 0.84 for rivaroxaban and 0.84 for enoxaparin.

Conclusion(s): The ClotPro RVV-test can be used as a readily accessible and rapid alternative to anti-Xa testing for detection of clinically relevant anticoagulant activity. The use of ClotPro RVV as a potential measure of residual anti-Xa activity in the presence of andexanet alfa should be explored.