The new direct oral
anticoagulants (DOACS)
dabigatran,
rivaroxaban,
apixaban and
edoxaban provide alternatives to
warfarin for treatment and prevention of
atrial fibrillation and venous thromboembolic disease in various settings. These have been developed as not requiring laboratory monitoring; however, under certain clinical situations, including recent haemorrhage/
thrombosis, emergency
surgical procedures, testing may be indicated.The aim of this study was to assess findings of haemostasis laboratory tests for one of the DOACs,
dabigatran (
Pradaxa), tested across a wide range of laboratory assays.Laboratories (n = 72) enrolled in the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Haematology program were sent set(s) of seven
dabigatran spiked plasma samples covering the concentration 0-800 ng/mL. Also, 30 ex vivo patient samples under
therapy with
dabigatran were assessed.Prothrombin time and activated partial thromboplastin time assays showed some sensitivity to
dabigatran; however, a normal result could not inform on drug exclusion. The thrombin time (TT) was very sensitive to
dabigatran, and a normal TT could generally be used for drug exclusion. More specialised assays such as the Hemoclot, a direct
thrombin inhibition assay, and in-house dilute TT methods, showed good reproducibility and concordance with expected drug levels assessed by mass spectrometry and were effective to quantify drug levels.
Dabigatran also affected factor assays,
lupus anticoagulant and factor inhibitor measurement, leading to potential misinterpretation of test results. Ex vivo sample testing provided similar and extended information.Dabigatran affects many haemostasis tests. Some can be used to predict the presence, absence or quantity of
dabigatran in patient plasma. For others, interference may lead to false conclusions regarding patients' haemostatic status.