Normal global coagulation tests lack specificity to rule out DOAC-induced anticoagulation, but reagent-specific cutoffs for PT and aPTT provide >95% specificity for rivaroxaban and dabigatran.
Observational (n=96)
Do reagent-specific cutoffs for global coagulation tests improve the identification of DOAC concentrations <30 ng/mL compared to normal test results in DOAC-treated patients?
Reagent-specific cutoffs for global coagulation tests, rather than normal reference ranges, are required to safely rule out relevant DOAC-induced anticoagulation for emergency decision making.
BACKGROUND AND PURPOSE: In patients receiving direct oral anticoagulants (DOACs), emergency treatment like thrombolysis for acute ischemic stroke is complicated by insufficient availability of DOAC-specific coagulation tests. Conflicting recommendations have been published concerning the use of global coagulation assays for ruling out relevant DOAC-induced anticoagulation. METHODS: Four hundred eighty-one samples from 96 DOAC-treated patients were tested using prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin time (TT), DOAC-specific assays (anti-Xa activity, diluted TT), and liquid chromatography-tandem mass spectrometry. Sensitivity and specificity of test results to identify DOAC concentrations 95% specificity and a specific TT cutoff enhanced sensitivity for dabigatran to 84%. For apixaban, no cutoffs could be established. CONCLUSIONS: Even if highly DOAC-reactive reagents are used, normal results of global coagulation tests are not suited to guide emergency treatment: whereas normal PT and aPTT lack specificity to rule out DOAC-induced anticoagulation, the low sensitivity of normal TT excludes the majority of eligible patients from treatment. However, reagent-specific cutoffs for global coagulation tests ensure high specificity and optimize sensitivity for safe emergency decision making in rivaroxaban- and dabigatran-treated patients. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifiers: NCT02371044 and NCT02371070.
Ebner et al. (Fri,) conducted a observational in DOAC-treated patients (n=96). Global coagulation assays (PT, aPTT, TT) vs. DOAC-specific assays and liquid chromatography-tandem mass spectrometry was evaluated on Sensitivity and specificity of test results to identify DOAC concentrations <30 ng/mL. Normal global coagulation tests lack specificity to rule out DOAC-induced anticoagulation, but reagent-specific cutoffs for PT and aPTT provide >95% specificity for rivaroxaban and dabigatran.