Point-Of-Care Testing of Fibrinogen by the qLab FIB System in Patients Taking Direct Oral Anticoagulants (DOACs)

Fibrinogen deficiency is common in acute haemorrhage and requires prompt treatment to prevent exacerbation of coagulopathy. Conventional lab measurements are time consuming, leading to delayed intervention or empirical fibrinogen replacement, potentially exposing patients to unnecessary transfusion. The qLabs FIB system offers rapid point-of-care measurement of fibrinogen at the bedside; however, its use in patients taking Direct Oral Anticoagulants (DOACs) has not been evaluated.

Thirty patients chronically anticoagulated with Apixaban or Edoxaban undergoing catheter ablation procedures for atrial fibrillation were recruited. Citrated blood samples were taken from each patient and assessed using the qLab FIB system, and lab-based Clauss assay (HemosIL Q.F.A. Thrombin (QFA), Werfen, Bedford, USA). DOAC levels were also measured, then removed using DOAC-Remove (Quadratech, UK) to assess their impact. Statistical analysis was performed using Bland-Altman, Passing-Bablok regression and paired t-tests.

A strong linear correlation (r = 0.88) was observed between the two methods; however, the qLabs FIB system consistently overestimated fibrinogen levels compared to the Clauss assay, with a mean bias of +0.50 g/L (95% LOA: -0.03 to +1.02 g/L). The Passing-Bablok slope of 0.64 suggested that overestimation might be more pronounced at lower fibrinogen concentrations. DOAC presence did not significantly alter measurement results (p = 0.380), and DOAC concentration did not correlate with the measurement discrepancy.

The qLabs FIB system is a viable method for rapid assessment of fibrinogen levels in patients anticoagulated with DOACs. However, the presence of overestimation bias may have implications for clinical decision making.