Background: Detection and classification of anti-Factor Xa agents may be important in situations like trauma, stroke or emergent surgery where a key intervention (tissue plasminogen activator or reversal agent) will increase the odds of survival. Currently, no standardized point-of-care test is available to evaluate the anticoagulant effects of Apixiban .
Methods: Healthy volunteers (n=27) and patients on apixaban (n=50) were enrolled in this multi-center (n=5) observational study. Protocol was approved by site IRBs and informed consent was obtained prior to blood draw. To ensure that a range of drug concentrations were captured, blood samples were obtained at non-trough (<9hrs) and trough (9-12hrs) levels as indicated from last dose (2.5 or 5 mg, BID). The viscoelastic OAC assay utilizes human Factor Xa and Ecarin as reagents (AFXa and DTI assays, respectively). Data derived from patients on apixaban were compared against the reference range (based on a separate healthy cohort; n=111) to determine sensitivity and specificity for detection.
Results: Majority of patients were prescribed apixaban for atrial fibrillation. Patients had significantly longer Reaction Time (R) by AFXA assay (p <0.001) but not DTI assay (p=0.55) as compared to healthy volunteers. AFXA-R time >1.9 min indicated detection of anticoagulation effect with 96% sensitivity and 100% specificity (Fig 1A). DTI R-time cut-off < 2.3 min was classified as an anti-Xa with 98% sensitivity (Fig 1B). There was a large interindividual variability in anticoagulant effect that was not attributable to dose or trough levels.
Conclusions: The automated TEG6s device with its OAC assay may be an effective tool to rapidly identify anticoagulant effect in apixiban treated patients and facilitate care of patients with bleeding or at risk of bleeding in the event of needing emergency.