Interpretation of coagulation test results under direct oral anticoagulants

Abstract

Summary Diagnostic of global coagulation parameters is part of the daily clinical routine practice in conservative as well in operative disciplines. The correct interpretation of in vitro test results in context to the ex vivo influence of anticoagulant drugs and the in vivo hemostatic system of the individual patient is dependent on the doctors clinical and laboratory experience. This article shortly reviews the laboratory interference of oral anticoagulants including the target‐specific inhibitors dabigatran, rivaroxaban and apixaban on coagulation parameters and discusses the potential of several methods for measuring the anticoagulant effect of the direct oral anticoagulants.

Direct Oral Anticoagulants (DOACs) in the Laboratory: 2015 Review

“…was measurable. This effect may occur with other APTT-based factor assays, including factor IX and factor XI activity assays [41,42]. Therefore, APTT-based screening tests, mixing studies, factor activity analysis, and even Bethesda assays may yield spurious results in the presence of dabigatran, leading to a false impression of either a factor deficiency, or the presence of a specific factor inhibitor [29,41].…”

“…Dabigatran may cause false positive lupus anticoagulant (LA) results but will not affect ELISA-based antiphospholipid assays [41,43]. Chromogenic or latex immunoassays including plasminogen activity, quantitative D-dimer, free protein S antigen, chromogenic protein C activity, von Willebrand factor antigen, and von Willebrand factor activity (ristocetin cofactor), are not affected by the presence of dabigatran [41][42][43]. Laboratories with limited access to patient information (eg, reference laboratories) may require a mechanism (e.g.…”

Monitoring target-specific oral anticoagulants

“…Therefore, these assays, for example, measures of antithrombin, protein C, or protein S activity, APC resistance, and lupus anticoagulant testing, should not be performed in patients on these drugs. 23,[32][33][34] False-positive testing for lupus anticoagulants, even with a positive phospholipid correction step, have been reported in patients on each of these drugs. 34 Measures of antigen levels or DNA-based assays will not be affected by these drugs.…”

“…16,35 Fibrinogen measured using a prothrombin-based method may be artifactually elevated by all 3 drugs, the extent depending on the reagent used. 33 Individual clotting factor assays may also be affected. This will depend in part on the reagent and methodology used.…”

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

“…We confirmed that to reliably evaluate LA in VTE patients on rivaroxaban, blood should be taken at least 24 h after the last drug administration [69]. It has been recommended that the LA testing should be performed 2-3 days after the last dose of DOACs [71].…”