Measurement of non‐Coumarin anticoagulants and their effects on tests of Haemostasis: Guidance from the British Committee for Standards in Haematology

Abstract

The guideline group was selected to include UK-based medical, scientific and laboratory representatives. Publications known to the writing group were supplemented with additional papers identified by searching MEDLINE/Pubmed using the keywords direct thrombin inhibitors (DTI), direct Xa inhibitors, apixaban, argatroban, bivalirudin, dabigatran, fondaparinux, rivaroxaban, in combination with measurement, monitoring, coagulation assays, haemostasis assays and laboratory tests.The writing group produced the draft guideline, which was subsequently revised by consensus by members of the Haemostasis and Thrombosis Task Force of the British Committee for Standards in Haematology (BCSH). The BCSH GRADE system was not applied to this guideline as it is inappropriate for laboratory studies. The guideline was then reviewed by a sounding board of c. 50 UK haematologists, the BCSH and British Society for Haematology (BSH) Committee and comments were incorporated where appropriate.The objective of this guideline is to provide healthcare professionals with clear guidance on the clinically important issues regarding the laboratory assessment of currently used non-coumarin anticoagulants and their impact on laboratory tests of haemostasis.A short summary of the effects of rivaroxaban and dabigatran on routine coagulation screens and assessment of anticoagulation intensity on behalf of the BCSH and international recommendations related to measurement of oral direct inhibitors (Baglin et al, 2013) have recently been published.The sections on heparin and low molecular weight heparin (LMWH) represent an update of the previously issued guidance (Baglin et al, 2006).

Point-of-Care Testing of Coagulation in Patients Treated With Non–Vitamin K Antagonist Oral Anticoagulants

“…3 Routine coagulation assays like prothrombin time (PT) and activated partial thromboplastin time (aPTT) provide qualitative rather than quantitative information about the presence of NOAC. 4 Both routine and NOAC-specific assays are usually conducted in central laboratories, and therefore results are inevitably delayed by sample transportation and preparation.…”

Management of Novel Oral Anticoagulants in the Perioperative Setting

“…Currently there are several key unknowns to NOACs that make other anticoagulants, such as warfarin, more favourable to manage in an emergency situation [6]. These include the uncertainty of safe operative NOAC concentrations, and the inaccuracy of coagulation studies to determine the anticoagulant effect [6].…”

“…NOACs hold many advantages over warfarin in the management of procoagulant disorders, such as their rapid onset with no bridging required, short half-life allowing timely cessation and not requiring monitoring blood tests [3][4][5]. The advantage of not requiring monitoring blood tests is, however, a disadvantage in the perioperative setting, as coagulation studies are therefore a poor predictor of agent reversal [6]. What's more, reversal is difficult.…”

Direct Oral Anticoagulants in Patients with Thrombophilia: Challenges in Diagnostic Evaluation and Treatment

“…The APTT demonstrates a concentration-dependent prolongation in a nonlinear manner in response to direct FXa inhibitors in samples, although to a lesser extent than to dabigatran [48,[63][64][65]. APTT reagents are much more sensitive to rivaroxaban and edoxaban than to apixaban [52].…”

“…Thrombin time (TT) is very sensitive to dabigatran, and low concentrations of 25 ng/mL may render the tested plasma samples unclottable [60,65]. A normal standard TT can exclude the presence of dabigatran in a sample [67].…”