Table 2

Suggestions for Laboratory Measurement of DOACs When Specialized Assays are Available

DrugClinical Objective
Exclude Clinically Relevant Drug LevelsMeasure On-Therapy or Above On-Therapy Drug Levels
Suggested TestInterpretationSuggested test
DabigatranDilute TT
ECT
ECA
Normal result probably excludes clinically relevant levelsDilute TT
ECT
ECA
Apixaban, edoxaban, or rivaroxabanAnti-XaAbsent chromogenic anti-Xa assay activity probably excludes clinically relevant levelsAnti-Xa

Anti-Xa = anti–factor Xa; aPTT = activated partial thromboplastin time; DOAC = direct-acting oral anticoagulant; ECA = ecarin chromogenic assay; ECT = ecarin clotting time; PT = prothrombin time; TT = thrombin time.

  • The term “clinically relevant” refers to DOAC levels that may contribute to bleeding or surgical bleeding risk. The minimum DOAC level that may contribute to bleeding or surgical bleeding risk is unknown. The International Society on Thrombosis and Hemostasis recommends consideration of anticoagulant reversal for patients with serious bleeding and a DOAC level >50 ng/mL, and for patients requiring an invasive procedure with high bleeding risk and a DOAC level >30 ng/mL (17).

  • Useful for quantification of plasma drug levels only when calibrated with the drug of interest.