Abstract
The impact of direct oral anticoagulants (DOACs) on laboratory assays used for thrombophilia testing (e.g., antithrombin, protein S, protein C, lupus anticoagulant and activated protein-C resistance) is a well-known issue and may cause false-positive and -negative results. Therefore, the correct interpretation of tests that are performed in patients taking DOACs is mandatory to prevent misclassification and the subsequent clinical consequences. We aimed at evaluating the efficiency of a new and simple procedure (DOAC-Stop®; Haematex Research, Hornsby, Australia) to overcome the effect of all DOACs in real-life settings and to assess the percentage of erroneous results due to the presence of DOACs on thrombophilia screening tests. For this purpose, 135 DOAC-treated patients (38 apixaban, 40 dabigatran, 15 edoxaban, and 42 rivaroxaban) and 20 control patients were enrolled. A significant drop in apixaban, dabigatran, edoxaban, and rivaroxaban plasma concentrations following the DOAC-Stop® treatment was observed (74.8–8.2 ng/mL [ p < 0.0001], 95.9–4.7 ng/mL [ p < 0.0001], 102.1–8.8 ng/mL [ p = 0.001], and 111.3–7.0 ng/mL [ p < 0.0001], respectively). The DOAC-Stop® treatment was mostly effective to overcome the effect of DOACs on PTT-LA, dilute Russell's viper venom time (dRVVT) screen, and dRVVT confirm tests. Using our procedures, false-positive results due to DOACs were observed only with lupus anticoagulant tests (up to 75%) and fell to zero after the DOAC-Stop® procedure, regardless of the DOAC considered. In conclusion, the DOAC-Stop® adsorbent procedure appeared to be an effective and simple way to overcome the interference of DOAC on coagulation tests and should facilitate the interpretation of thrombophilia screening tests in patients taking DOACs.
Highlights
The Direct oral anticoagulants (DOACs)-Stop® treatment was mostly effective to overcome the effect of DOACs on PTT-LA, dilute Russell’s viper venom time screen, and dRVVT confirm tests
The DOAC-Stop® adsorbent procedure appeared to be an effective and simple way to overcome the interference of DOAC on coagulation tests and should facilitate the interpretation of thrombophilia screening tests in patients taking DOACs
The residual level of each DOAC was lower than the limit of quantification of the corresponding apixaban, dabigatran, edoxaban, and rivaroxaban assays.[16,17,18,19]
Summary
Several strategies were proposed to minimize the impact of residual DOACs on coagulation assays: (1) the use of DOACinsensitive assays, (2) the addition of idarucizumab to the plasma sample (Praxbind, Boehringer Ingelheim) to neutralize the in vitro activity of dabigatran,[10] or (3) missing one (for once-daily fixed-dose regimens) or two (for twice-daily fixed-dose regimens) DOAC intake in patients with low thromboembolic risk.[6] any interruption of anticoagulation will expose the patient to an increased risk of thrombosis and residual drug levels may still affect test results.[7] none of these approaches are considered optimal and a simple way to overcome the problem would be to remove DOAC from the plasma sample without influencing its coagulant property
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