PB1060 - Evaluation of the Tsmart® FIB Batrox Assay for Point-of-Care Measurement of Fibrinogen Levels from a Single Drop of Citrated Whole Blood

Background: Point-of-care (POC) testing plays an important role in guiding fibrinogen repletion in clinical settings such as cardiovascular surgery, postpartum hemorrhage, and trauma. The Tsmart® FIB Batrox (Biosynex, France) is a single-use microcuvette using an innovative microfluidic capillary channel containing lyophilized batroxobin, a thrombin-like serine protease from Bothrops atrox venom. The product is at validation stage and is not commercialized yet. Once inserted into the LabPad® Evolution POC device (Biosynex, France), it enables to quantify fibrinogen levels within 4 minutes from a single drop of citrated blood. The assay is insensitive to hematocrit, triglycerides, bilirubin, heparin, protamine sulfate, and oral anticoagulants.

Aims: To evaluate the analytical performances of the Tsmart® FIB Batrox prototypes for POC measurement of fibrinogen levels

Methods: This prospective, single-center study was conducted at Pitié-Salpêtrière hospital during January 2024. We used residual citrated blood samples collected for routine coagulation testing. Fibrinogen levels were immediately determined using a Tsmart® FIB Batrox microcuvette inserted into a LabPad® device. For each sample, the fibrinogen level was also determined at the core laboratory using the STA®-Liquid Fib reagent on a STA-R Max analyzer (Stago, France).

Results: Passing Bablok regression analysis showed an excellent correlation between the Tsmart® FIB Batrox and the predicate assay (n=35, r=0.87, p< 0.0001, Figure 1). Bland-Altman analysis revealed a high level of agreement between the Tsmart® FIB Batrox and the predicate assay (Figure 2). Using a clinical cut-off value of 2.0 g/L, the area under the receiver operating characteristic curve of the Tsmart® FIB Batrox was 0.973 (sensitivity, 93.3% %; specificity, 90.0%). The Tsmart® FIB Batrox provided results significantly faster than the predicate assay (median time 67 versus 3 minutes, p< 0.0001).

Conclusion(s): The Tsmart® FIB Batrox provides timely information to guide fibrinogen replacement in critical care by rapidly and reliably measuring fibrinogen levels from a single drop of citrated whole blood.