From single to dual platelet inhibition FIBTEM assay: fibrinogen replacement thresholds for critical bleeding after trauma

PURPOSE: ) measures fibrin-based clot formation. The reagent transitioned from single to dual-platelet inhibition with addition of tirofiban to cytochalasin D, offering more complete platelet suppression. The aim of this study was to assess the impact of this change on transfusion thresholds in trauma. METHODS: In this retrospective cohort study, we included adult patients with major trauma across Queensland who presented between 2022 and 2025 and had results available for paired ROTEM and conventional coagulation tests on arrival. Patients were sub-grouped into single and dual-platelet inhibition assay groups. Correlations between FIBTEM-A5 and Clauss fibrinogen were analysed, comparing correlation strength and diagnostic accuracy for fibrinogen levels of < 2.0 g/L. RESULTS: The relationship between FIBTEM-A5 and Clauss fibrinogen was similar using single platelet inhibition assays (R² 0.61;95%CI: 0.51-0.70) and dual-platelet inhibition assays (R² 0.70;95%CI: 0.62-0.77; p = 0.94). Predicted FIBTEM-A5 amplitudes at 2 g/L fibrinogen were 7.83 mm (95%CI: 7.42-8.23) and 7.54 mm (95%CI: 7.22-7.87). Diagnostic performance for detecting fibrinogen < 2.0 g/L was comparable between assays, for both FIBTEM-A5 ≤ 10 mm and FIBTEM-A5 ≤ 8 mm (all p > 0.05). For the dual-platelet inhibition assay, sensitivity and specificity were 97.8% and 48.1% at ≤ 10 mm, and 92.1% and 74.7% at ≤ 8 mm. CONCLUSION: Dual-platelet inhibition did not alter the relationship between FIBTEM-A5 and Clauss fibrinogen or the diagnostic accuracy of FIBTEM thresholds for identifying hypofibrinogenemia. FIBTEM-A5 ≤ 10 mm maintained high sensitivity, while ≤ 8 mm demonstrated greater specificity. Recalibration of established FIBTEM thresholds is not required following transition to dual-platelet inhibition.