OC 57.3 - A Point-of-Care analyzer (microDOAC) for the semi-quantitative analysis of direct oral anticoagulant (DOAC) concentration: a pilot study of apixaban-treated patients.

Background: Although direct oral anticoagulants (DOACs) do not require routine laboratory monitoring, laboratory measurement at the point-of-care (POC) may be useful for management of emergency situations including bleeding or need for urgent surgery. MicroDOAC, a handheld analyzer for whole blood POC DOAC measurement, demonstrated excellent performance in an in vitro study. Here we present results in a study of apixaban-treated patients.

Aims: To assess microDOAC test performance in apixaban-treated patients at clinically relevant selected levels and to demonstrate commutability between in-vitro spiked samples and ex-vivo samples.

Methods: Nonanticoagulated donor samples as well as samples from patients on apixaban. Whole blood samples were directly applied on microDOAC strip. In-vitro samples were obtained from normal donors spiked with increasing DOAC concentrations. The remaining volume was added to 3.2% sodium citrate for measurement of apixaban levels by anti-FXa activity (Stago). Receiver operator characteristic (ROC) curves were used to identify the assay values (in seconds) that best discriminate DOAC levels ≥30, ≥50, ≥75 or ≥100 ng/mL. For each threshold, sensitivity, specificity, and agreement were assessed. The Clinical and Laboratory Standards Institute EP14-A3 protocol was followed for commutability.

Results: 304 samples from 38 apixaban-treated patients and 120 samples from 15 normal donors were tested. 53% of samples were collected at peak (2-4 hours after drug intake) and 47% at trough (10-13 hours drug intake). The microDOAC test demonstrated high sensitivity and specificity values (>91%) for apixaban patient samples (Table 1) at clinically relevant cut-offs. 95.7 % of the spiked apixaban results fell within the prediction interval for patient samples, indicating commutability of in-vitro as compared to ex-vivo samples (Fig.1).

Conclusion(s): The results of this pilot study underline the potential of whole blood POC testing (microDOAC) as a rapid and reliable method for assessing clinically relevant DOAC levels in patients treated with apixaban.