Multicenter evaluation of the Quantra with the QStat Cartridge in adult trauma patients

Abstract

Background: Trauma-induced coagulopathy (TIC) occurs in a quarter of trauma patients and is associated with death due to uncontrolled bleeding. Current guidelines recommend viscoelastic testing (VET) to assess coagulopathy and guide transfusions. The Quantra with the QStat Cartridge is a point-of-care (POC) VET device that measures changes in clot stiffness (CS) during coagulation and fibrinolysis using ultrasound detection of resonance. This study aimed to evaluate the performance of the QStat Cartridge in trauma patients compared with rotational thromboelastometry (ROTEM) delta and thromboelastography (TEG) 6s VET devices.

Methods: A multicenter prospective observational study was conducted in adult patients meeting criteria for a full trauma team response at eight US level 1 trauma centers. Citrated blood samples drawn on arrival at the hospital or after blood transfusions were analyzed in parallel on QStat, ROTEM or TEG. Correlation between QStat and equivalent VET measurements was assessed by linear regression. Concordance was assessed by agreement of results relative to device-specific normal reference ranges.

Results: 259 severely injured patients were enrolled, yielding 271 samples for analysis. Moderate to strong correlations between QStat and corresponding ROTEM and TEG measurements were observed (r=0.64-0.88). The concordance between CS results was 84.5% for QStat CS and EXTEM A10 and 83.3% for CS and citrated rapid TEG maximum amplitude. For fibrinogen-related results, concordance was 81.5% for QStat fibrinogen contribution to clot stiffness (FCS) and FIBTEM A10 and 93.8% for FCS and citrated functional fibrinogen maximum amplitude. For fibrinolysis measurements, the overall agreement between QStat clot stability to lysis and EXTEM ML or CK-LY30 was 97.5% and 92.9%, respectively.

Conclusion: QStat provides comparable information to the ROTEM delta and TEG 6s in trauma patients and can be useful for diagnosing TIC and guiding treatment. The Quantra's simplicity of use, ability to deploy at the POC, and rapid availability of results may provide clinicians with a faster, more convenient means to assess and manage TIC.

Level of evidence: Diagnostic test, level II.

Trial registration number: NCT04312958.

Keywords: blood coagulation tests; fibrinolysis; hemorrhage.

Figure 1. Flow diagram of subject selection and sample collection. ROTEM, rotational thromboelastometry; TEG, thromboelastography.

Figure 2. Scatter plots showing correlation between Quantra QStat and related ROTEM delta measurements. (A) QStat CT vs. INTEM CT. (B) QStat CS vs. EXTEM A10. (C) QStat FCS vs. FIBTEM A10. (D) QStat PCS vs. PLATEM A10. The CS values for ROTEM delta (EXTEM and FIBTEM A10) were converted from clot amplitude in units of millimeters to elasticity in units of hectopascals using a validated conversion formula (24). PLATEM A10 is not a parameter output by the ROTEM delta but was calculated offline by subtracting FIBTEM A10 from EXTEM A10 after conversion to hectopascals. CS, clot stiffness; CT, clot time; FCS, fibrinogen contribution to clot stiffness; PCS, platelet contribution to clot stiffness; ROTEM, rotational thromboelastometry.

Figure 3. Scatter plots showing correlation between Quantra QStat and related TEG 6s measurements. (A) QStat CT vs. CK-R. (B) QStat CS vs. CRT-MA. (C) QStat FCS vs. CFF-MA. The CS values for TEG 6s (CRT-MA and CFF-MA) were converted from clot amplitude in units of millimeters to elasticity in units of hectopascals using a validated conversion formula (24). CFF-MA, citrated functional fibrinogen maximum amplitude; CK-R, citrated kaolin reaction time; CRT-MA, citrated rapid TEG maximum amplitude; CS, clot stiffness; CT, clot time; FCS, fibrinogen contribution to clot stiffness; TEG, thromboelastography.

Figure 4. QStat differentiates fibrinolysis from clot retraction. QStat dials and curves generated for samples from two trauma patients: (A) indicating the presence of fibrinolysis and (B) indicating the absence of fibrinolysis with evidence of clot retraction. The CSL parameter is calculated as the normalized difference between the CS change after maximum CS assessed in the presence and absence of TXA. (A) Sample shows a fibrinolysis positive signal (CSL is 41%, below the threshold of 90%), with a rapid decline in CS in the absence of TXA (channel 3—yellow), while there is no decline in the presence of TXA (channel 2—orange). (B) Sample shows a negative fibrinolysis signal (CSL is 100%, above the threshold of 90%). Although there is a decline in CS in the absence of TXA (channel 3—yellow), this decline is similar in the presence of TXA (channel 2—orange). Consequently, the observed decline in CS is not due to fibrinolysis but is caused by clot retraction. CS, clot stiffness; CSL, clot stability to lysis; CT, clot time; FCS, fibrinogen contribution to clot stiffness; PCS, platelet contribution to clot stiffness; TXA, tranexamic acid.