Non vitamin K oral anticoagulants (NOACs) do not require regular monitoring but information about their pharmacodynamic effect may be importantin situations like trauma, stroke oremergent surgery. Currently, no standardized point-of-care test is available to evaluate the anticoagulant effects of NOACs. We evaluated the anticoagulant effect of NOACs with the next generation point-of-care TEG assay (TEG® 6S) based on a fully-automated thrombelastography system. We used two TEG® 6S assays, the DTI assay and Anti-Factor Xa (AFXa) assay, to detect anticoagulant effects and classify NOACs. Blood from healthy volunteers (n = 26) was used to obtain a baseline reference range. Data derived from patients on factor Xa inhibitors (FXi) (rivaroxaban and apixaban) (n = 39), and direct thrombin inhibitors (DTIs) (dabigatran) (n = 25) were compared against the reference range for detection of drug effect and drug classification. TEG®6s R-time highly correlated to each NOAC. Presence of NOACs caused elongation of R-time on the AFXa assay compared to the reference range (4.3 ± 1.7 vs. 1.3 ± 0.3 min. for FXi, p < 0.001 and 3.5 ± 1.2 vs. 1.3 ± 0.3 min. for DTI, p < 0.001). R-time on the DTI assay was elongated only in presence of a DTI (3.4 ± 1.0 vs. 1.5 ± 0.2 min, p < 0.001). The cutoff for detection of a DTI effect was an R time of 1.9 min and for anti-Xa effect was 1.95 min. For detection of NOAC therapy, there was ≥92% sensitivity and ≥95% specificity. The automated TEG®6s NOAC assay may be an effective tool to identify an anticoagulant effect from NOAC therapy and facilitate care of patients with bleeding or at risk of bleeding in the event of needing emergency surgery.

BACKGROUND The trauma patient on direct oral anticoagulant (DOAC) therapy preinjury presents a challenge in trauma and acute care surgery. Our understanding of these patients is extrapolated from vitamin K antagonists. However, DOACs have different mechanisms of action, effects on laboratory coagulation assays, and reversal strategies. Rapid identification of DOACs in the blood will allow timely reversal of factor Xa inhibitors and direct thrombin inhibitors when necessary. The present study evaluated viscoelastic testing to detect and classify DOACs in patient blood samples. METHODS This observational, prospective, open-label, multicenter study used point-of-care viscoelastic testing to analyze blood samples taken from patients with and without DOAC treatment, and healthy volunteers. Antifactor Xa and direct thrombin inhibition (DTI) assays were used to establish reference ranges for viscoelastic testing parameters on the TEG 6s system. These ranges were applied to produce a DOAC identification algorithm for patient blood samples. Internal consistency of the measurements, as well as algorithm sensitivity and specificity, was evaluated. RESULTS Using the TEG 6s system, the R parameter reference range was 0.6 minutes to 1.5 minutes for the Antifactor Xa assay and 1.6 minutes to 2.5 minutes for the DTI assay. Our identification algorithm using these ranges for 2.5 minutes or less has sensitives of 98.3% and 100% for factor Xa inhibitor and direct thrombin inhibitor detection, respectively. Specificity was 100%. Both classes of DOAC were detectable, even when samples were collected during the “trough” between doses of medication. CONCLUSION Point-of-care viscoelastic testing with TEG 6s can detect and classify DOACs with high sensitivity and specificity. This tool can be used to better determine the need for reversal in trauma and acute care surgery patients and guide optimal surgical timing in the acute setting. LEVEL OF EVIDENCE Prognostic and epidemiological study, level II.