Resolving DOAC interference on aPTT, PT, and lupus anticoagulant testing by the use of activated carbon

Abstract

Background: Direct oral anticoagulants (DOACs) affect laboratory coagulations tests. Activated carbon (AC) can be used for adsorption of DOACs during acute human intoxications. Objectives: This study evaluates whether AC can also be used to resolve DOAC interference on in vitro clotting tests (prothrombin time [PT], activated partial thromboplastin time [aPTT], and lupus anticoagulant [LA] assays).

The effect of DOACs on laboratory tests and their removal by activated carbon to limit interference in functional assays

“…A particular version in mini‐tablet form was developed for more convenient application to 1ml volumes of test plasmas (DOAC Stop™, Haematex). Several studies have now been published which confirm that it and similar products (DOAC Remove) may be useful in blood coagulation testing labs to eliminate the in vitro effect of DOACs 6‐16 ; especially in testing for lupus anticoagulant.…”

“…The low phospholipid LA screen tests are not specific just for LA and are similarly prolonged by DOACs 19,20 . Abnormal LA screen results are obtained on most DOAC patient plasmas 7,10,13,14,30 . The dRVVT screen/confirm ratio is less affected but with higher levels of rivaroxaban (and to a lesser extent dabigatran) these can be above the usual cutoff.…”

Guidance from the Scientific and Standardization Committee for lupus anticoagulant/antiphospholipid antibodies of the International Society on Thrombosis and Haemostasis

“…Use of antidotes or neutralizers have been investigated to eliminate and overcome the effect of DOACs 39‐42 . Several studies indicated that pretreatment with adsorbents may affect clotting times resulting in false‐positive or false‐negative LA results, or incomplete removal of DOACs 33,41‐43 . Consequently, pretreatment of plasma with adsorbents is only advised in DOAC‐treated patients 16 .…”

Guidelines on the laboratory aspects of assays used in haemostasis and thrombosis

“…If indicated, the presence of a normal thrombin time (TT) effectively excludes the presence of a thrombin inhibitor or significant contamination with unfractionated (but not low molecular weight) heparin. Commercial products such as DOAC‐Stop (Haematex, Hornsby, NSW, Australia), 15–17 DOAC‐Remove (5‐Diagnostics, Basel, Switzerland), 18 20 mg/ml of activated charcoal 19 or Adexanet alfa 20 have been shown to remove the effect of DOAC. However, if used, results should be interpreted with caution as there may be differing limits to the concentration of the DOAC they can remove 15,17 …”