Abstract
Introduction:
Calibrated automated thrombography (CAT) assay parameters have been shown to assess hypercoagulation state and, therefore, may independently predict post-trauma, symptomatic venous thromboembolism (VTE). Yet, CAT lacks high throughput and standardization, limiting diagnostic potential. This study analyzed thrombin generation profiles in trauma patients using a high throughput assay, processing up to 10 samples at once, providing batch testing capabilities. We hypothesized that trauma patients who developed VTE would show distinct thrombin generation profiles compared to those who did not.
Methods:
Trauma patients presenting to a Level I Trauma Center had samples collected within 12 hours post-injury prospectively. Follow-up was conducted to 90 days, time to symptomatic VTE diagnosis or death, confirmed via autopsy or imaging. Thrombin generation profiles were measured from the ST Genesia assay. Data was presented as median [IQR] or n (%), with Wilcoxon rank-sum or chi-squared test. Associations between thrombin generation parameters and clinical risk factors were assessed using Spearman correlation analysis or the Wilcoxon rank-sum test.
Results:
Two-hundred and fifty-four trauma patients were analyzed (48.5 years [31.0, 62.0], 72.0% male): 64 patients with VTE (25.2%) to 190 with non-VTE. VTE pts had a median time to VTE of 8 days, with 29 developing deep venous thrombosis (DVT), 24 with pulmonary embolism (PE), and 11 with DVT/PEs. No significant differences were found in age, sex, or Body Mass Index (BMI); significantly more VTE patients underwent surgery and blood transfusions within 24 hours. Thrombin generation profiles demonstrated accelerated thrombin generation in patients who developed VTE compared to non-VTE, with significant differences in Peak Height (p=0.001), Time to Peak (p=0.021), Endogenous Thrombin Potential (p<0.001) and Velocity Index (p=0.001.
Conclusion:
Thrombin generation profiles using ST Genesia can differentiate trauma patients at high risk of developing VTE. The platform suits clinical labs needing high throughput by providing batch testing capabilities. Study Type: Prospective study with less than large effect and no negative criteria.
Level of Evidence:
II
Keywords: thrombin generation, Trauma, Venous thromboembolism
Social Media Information:
Handles: @sergmnavarro, @taleenmacarthur; Hashtags: #VTE, #thromboinflammation, #trauma; Tweet: “Platform-based assessment tool shows accelerated thrombin generation in symptomatic VTE patients compared to non-VTE patients, as early as three hours following injury.”
Visual Abstract
INTRODUCTION:
Systemic inflammation and coagulation comprise the physiological response to trauma. Damage-associated molecular patterns (DAMPs) released after injury are proinflammatory, increasing endothelial permeability and promoting neutrophil-endothelial interactions.1 Furthermore, findings highlight the interconnected and synergistic roles of platelet reactivity, coagulation, neutrophil priming, and inflammatory tissue injury in such contexts.2
While it has been previously shown that thrombin generation is accelerated in trauma-induced coagulopathy and in venous thromboembolism, thrombin generation acceleration and its linkage in the development of venous thromboembolism (VTE) in the trauma population remains to be fully characterized in a broader multi-institutional clinical setting.3,4 This requires the standardized quantification of the kinetics of plasma thrombin generation in a trauma population.
The calibrated automated thrombogram (CAT) is a dynamic assay which quantifies plasma thrombin generation at a given point in time in response to tissue factor (TF) and procoagulant phospholipid (PS), capturing a cascade of events triggered by blood exposure to TF after trauma.2,4. Several of these thrombin generation assay parameters have been previously shown to independently predict symptomatic venous thromboembolism (VTE) up to 90 days post-injury.4
In spite of these benefits offered with quantification of thrombin generation, the CAT lacks high throughput and standardization, limiting its wide clinical adoption outside of research settings.5 More recently, the ST Genesia platform (Diagnostica STAGO SAS, Asnières sur Seine, Belgium) provides opportunities for a more automated assay with improved temperature control.6 Furthermore, this thrombin generation assay (TGA) platform offers further ability for processing multiple samples with specialized kits, including those for quality control and clinical conditions, via batch testing, similar to complete blood count (CBC) and other standardized laboratory tests.7,8
In this study, we analyzed thrombin generation profiles of trauma patients using a platform-based system, processing up to 10 samples at once, enabling batch sampling. We hypothesized that we would be able to analyze a set of thrombin generation profiles in trauma patients and identify that trauma patients who developed VTE would show accelerated thrombin generation profiles compared to those who did not, based on ST Genesia platform parameters.
METHODS:
This study was conducted in accordance with the STROBE-type study guidelines, which were used to ensure proper reporting of methods, results, and discussion, as shown in Figure 1. A STROBE checklist is available in the Appendix.
Figure 1: Diagram of Samples from Trauma Patients Obtained within 12 hours from Time of Injury (TOI).
Legend: Study flow-chart of samples collected for healthy volunteers and trauma patients obtained from TOI, separated into patients developing symptomatic venous thromboembolism (VTE) and those who did not. Analyzed number was limited by available reagent for analysis. VTE, venous thromboembolism. TOI, Time of Injury.
Study Design and Database
This is a sub-study of a single-center enrollment from an ongoing parent, multi-center prospective case-cohort (3 Level 1 Trauma Centers) study that is investigating thrombin generation profiles of trauma patients and other thromboinflammatory biomarkers predictive of VTE in trauma patients.9 The study was approved by the Institutional Review Board. Beginning in 2018, all level I and II trauma activation patients presenting to a Level I Trauma Center were considered for inclusion in this study.9 Exclusion criteria were: refusal or inability to obtain informed consent from a patient or their Legal Authorized Representative, therapeutic anticoagulation (e.g. dabigatran, etexilate, rivaroxaban, apixaban), an inherited or acquired coagulation disorder (e.g. including known history of VTE or inherited thrombophilia), presentation >12 hours after injury, active cancer, sepsis, renal failure, or burns.
Samples were collected on arrival to the Trauma Center, with time of injury recorded based on pre-hospital or emergency medical service reporting. Up to 3 time points of samples were collected per patient, within time windows of 0–3 hours, 3–9 hours, and 9–15 hours from time of injury (TOI), denoted as 0–3 hour, 6 hour, and 12 hour samples, respectively. A secure electronic REDCap database was constructed to house data on patient demographics, transfusion, surgical interventions, and hospital complications including infections and VTE from inpatient and outpatient medical records.
A diagnosis of incident DVT or PE, either in hospital or within 92 days (365/4, or about 3 months) after hospital discharge, required objectively-diagnosed, symptomatic DVT or PE. The diagnosis of VTE required symptoms or signs of acute DVT or PE and a positive diagnostic imaging study (i.e., whole leg compression venous duplex ultrasonography; pulmonary angiography, computed tomographic pulmonary angiography). Routine screening leg venous duplex ultrasonography in search of asymptomatic DVT was not performed, in line with institutional guidelines. We implemented a standard post-discharge follow-up to identify symptomatic VTE cases. The institution’s clinical practice guidelines for VTE prophylaxis are in line with Western Trauma Association guidelines clinical decisions algorithm, with goal to reduce venous thromboembolism in trauma patients by emphasizing early initiation of both mechanical and chemical prophylaxis, within 24 hours of injury.10
From October 2018 through September 2023, 1,194 patients had been enrolled in the parent study; at the time of this sub-study, 87 of these were known to have been diagnosed with a VTE within 92 days of injury and 1,107 were not. All VTE patients were selected for analysis in the parent study, in addition to three randomly selected (by number randomization) non-VTE patients per VTE patient from the month before or after each VTE enrollment ensuring temporal proximity. From this parent cohort, a laboratory technician selected subjects for analysis for this sub-study, based on sample availability (at least 5 aliquots available), while maintaining the 3:1 non-VTE to VTE ratio as in the parent study. There was no added statistical power to analyses by having greater than a 3:1 non-VTE to positive VTE sampling ratio. Selection and analysis were performed until the lot of available ST Genesia thrombin generation assay reagent was depleted, resulting in 254 samples being tested: 64 from VTE patients and 190 from non-VTE patients.
Each patient’s earliest usable sample was analyzed. This was based on prior research that found that the first thrombin generation result within 12 hours of injury was approximately as predictive of VTE as the most hypercoagulable result within the same time period4, with Figure 1, following the STROBE guidelines, detailing the sample selection and analysis criteria. The selected VTE and nonVTE patients were representative of the larger cohort of enrolled VTE and non-VTE patients, respectively, with no significant differences in age, sex, race, BMI, ISS, or trauma mechanism between the analyzed and non-analyzed groups.
Sample Collection, Processing, and Storage
Whole blood was collected by venipuncture or via existing indwelling arterial or central venous catheters into 4.5 mL citrate Vacutainer® tubes (0.105M buffered sodium citrate, 3.2% Becton Dickinson, and Company Plymouth, UK) and processed (within 1 hour of collection) to platelet poor (cell-free) plasma by double centrifugation (3000g, 15 minutes), and stored in multiple aliquots at −80° Celsius until analysis as recommended by the International Society of Thrombosis and Haemostasis (ISTH) Vascular Biology Standardization Subcommittee.11
Thrombin Generation Using ST Genesia
Thrombin Generation (TG) was measured using the automated ST Genesia thrombin generation analyzer (Diagnostica Stago, Inc., Parsippany, New Jersey, USA). The ST Genesia measures the development of fluorescence of 7-amido-4-methyl coumaric acid (AMC) to detect thrombin activation calibrated once daily using a known thrombin concentration.7 The ST Genesia performs two or four TG measurements for each sample, depending on the trigger reagent, along with a separate set of two fluoSet (FS) cuvettes containing a fixed amount of the AMC fluorophore added to each plasma to correct for potential plasma color artifacts. The samples are preheated at 37°C with precise temperature control and the fluorescence is registered with a 377/440 filter set (excitation/emission). The kits contain dedicated quality control vials along with reference plasma for normalization of the TG values. All validation measures were performed using the same lot of reagents. Next, using STG-ThromboScreen (STG-TS) reagent kit, which consists of two activators of the same TF concentration and phospholipid content, the TG was measured without the addition of thrombomodulin (TM). Assays of trauma patient plasma samples were performed in duplicate, with TG-initiated and citrated platelet-poor plasma added to each cuvette. After an incubation period (5 minutes at 37°C), the FS reagent was added. Thrombin generation was recorded over time and produced by the ST Genesia analyzer. Key thrombin generation parameters include the LagTime [LT]; minutes, Endogenous Thrombin Potential (ETP; nM*minutes), Peak Height (PeakHeight; nM), time to peak (ttPeak; minutes), Velocity Index (Velocity Index; nM/minutes) and Start Tail (StartTail, minutes). An example representative thrombin generation profile with the depiction and descriptive definition of components of the TG parameters is available in Figure 2.12
Figure 2: Sample thrombin generation profile.
Legend: Representative thrombin generation assay curve, with key parameters identified, namely the time to initiation of thrombin generation; minutes (LagTime [LT]; minutes), the total amount of thrombin generated at a given point during the assay, known as the Endogenous Thrombin Potential (ETP; nM*minutes), the greatest level of thrombin reached on the thrombin generation curve in an individual’s plasma known as the Peak Height (PeakHeight; nM), the time to peak (ttPeak; min), reflecting the time of initiation up to the time of maximum thrombin generated in the individual’s plasma) and the rate of thrombin generation in an individual’s plasma known as the Velocity Index (reflecting the rate of thrombin generation; nM/minutes). Another variable, Start Tail, evaluates the time point where thrombin generation has come to an end and all the generated thrombin has been inhibited.
Statistical Analyses
Descriptive statistics are presented as frequency and percent or median values and interquartile ranges (IQR). Wilcoxon rank-sum test and Chi-Square test were used to detect differences in thrombin generation parameters and clinical characteristics between VTE trauma patients and non-VTE trauma patients. Associations between the thrombin generation parameters and other clinical characteristics were assessed using Spearman correlation analysis or Wilcoxon rank-sum test. A P-value of less than 0.05 was considered significant. Data analysis was performed using R Statistical Software, version 4.2.2.
RESULTS:
Demographic characteristics and clinical characteristics of the VTE trauma patients compared to non-VTE trauma patients are shown in Tables 1 and 2.
Table 1:
Demographic features of trauma venous thromboembolism (VTE) and non-VTE patients.
| Trauma VTE (n = 64) | Trauma non-VTE (n = 190) | p-value | |
|---|---|---|---|
| Age (years) | 50.0 [35.8, 60.3] | 47.0 [30.0, 62.0] | 0.75 |
| Race (% white) | 56 (88.9%) | 180 (95.7%) | 0.047 |
| Sex (% male) | 47 (73.4%) | 136 (71.6%) | 0.77 |
| Body Mass Index (BMI, kg/m2) | 30.0 [25.0, 35.5] | 27.9 [24.0, 32.4] | 0.12 |
| Current smoker (%) | 14 (22.2%) | 44 (24.3%) | 0.89 |
Baseline demographic features of VTE (n=64) and non-VTE trauma patients (n = 190). Results presented as median with quartiles [Q1, Q3] or categorical counts with percentages (%). Wilcoxon rank-sum test or chi-square test for difference between groups. P-value < 0.05 significant. Data for race was unavailable for 3 patients (1 VTE, 2 non-VTE) and data for smoking status was unavailable for 9 patients (0 VTE, 9 non-VTE) and not included in reported numbers and percentages.
Table 2:
Clinical characteristics of injured patients, with VTE patients compared to non-VTE patients.
| Total (n=254) | VTE (n=64) | Non-VTE (n=190) | p-value | |
|---|---|---|---|---|
| Mechanism of Injury | 0.99 | |||
| Blunt (%) | 238 (93.7%) | 60 (93.8%) | 178 (93.7%) | |
| Penetrating (%) | 16 (6.3%) | 4 (6.2%) | 12 (6.3%) | |
| Injury Severity Score (ISS) | 17 [10, 29] | 27 [16, 38] | 17 [9, 25] | <0.001 |
| Surgery within 24 hours (%) | 133 (52.4%) | 50 (78.1%) | 83 (43.7%) | <0.001 |
| Blood products within 24 hours (%) | 84 (33.1%) | 41 (64.1%) | 43 (22.6%) | <0.001 |
| Long Bone Fracture (%) | 115 (45.3%) | 44 (68.8%) | 71 (37.4%) | <0.001 |
| Pelvic Fracture (%) | 33 (13.0%) | 13 (20.3%) | 20 (10.5%) | 0.044 |
| Spinal Fracture (%) | 89 (35.0%) | 23 (35.9%) | 66 (34.7%) | 0.86 |
| Traumatic Brain Injury (%) | 93 (36.6%) | 24 (37.5%) | 69 (36.3%) | 0.87 |
| Days in ICU | 2 [0, 6] | 6 [3, 13] | 2 [0,4] | <0.001 |
| Days on ventilator | 0 [0,2] | 2 [0,6] | 0 [0,1] | <0.001 |
| Chemoprophylaxis within 24 hours (%) | 82 (32.3%) | 17 (26.6%) | 65 (34.2%) | 0.26 |
| Mechanical Prophylaxis within 24 hours (%) | 106 (41.7%) | 25 (39.1%) | 81 (42.6%) | 0.62 |
| Chemoprophylaxis or Mechanical Prophylaxis within 24 hours (%) | 156 (61.4%) | 36 (56.2%) | 120 (63.2%) | 0.33 |
Characteristics of all patients, with comparison of characteristics of patients developing venous thromboembolism (VTE) to patients that did not develop VTE. Results presented as median with quartiles [Q1, Q3] or categorical counts with percentages (%). Wilcoxon rank-sum test or chi-square test for difference between groups. P-value < 0.05 significant. Data for injury severity score (ISS) was unavailable for 11 patients (3 VTE, 8 non-VTE).
No differences were found in age (p=0.75), sex (p=0.77), current smoking status (p=0.89) or BMI (p=0.12).
Only 4 of 64 VTE patients and 12 of 190 non-VTE patients experienced penetrating trauma; the remaining VTE (n=60) and non-VTE (n =178) were blunt traumas (p=0.99). Injury Severity Score (ISS) was significantly higher in patients who went on to develop VTE than in those who did not (p<0.001). Furthermore, the percentage of patients who underwent surgery within 24 hours of injury was significantly higher in patients who developed VTE than in those who did not develop VTE (78.1% vs 43.7%, p<0.001). Sixty-four percent (n=41) of VTE patients required transfusion of blood products within 24 hours of injury, compared to just 23% (n=43) of non-VTE patients (p<0.001). Of the 84 patients who received blood transfusions within 24 hours of injury, 51 (61%) had their first transfusion prior to their first blood draw, including 41 (49%) prior to hospital arrival. More VTE patients than non-VTE patients experienced long-bone (p<0.001) and pelvic fractures (p=0.044), but rates of spinal fractures (p=0.86) and traumatic brain injuries (p=0.87) were similar. VTE patients also spent more time in the ICU (p<0.001) and on ventilator (p<0.001). Chemoprophylaxis and mechanical prophylaxis were administered at similar rates within the first 24 hours following injury.
VTE patients had a median time to VTE of 8 days, with 29 (45.3%) developing deep venous thrombosis (DVT), 24 (37.5%) with pulmonary embolism (PE), and 11 (17.2%) with DVT/PEs. Sixty-four percent of VTE patients had 0–3 hour samples, 31% had no 0–3 hour samples but had 3–9 hour samples, and 5% had only 9–15 hour samples, while the corresponding proportions for non-VTE patients were 52%, 39% and 9%, respectively.
A comparison of thrombin generation curve characteristics between patients who developed VTE and those who did not develop VTE yielded significant differences in Peak Height (p=0.001), ttPeak (p=0.021), ETP (p<0.001) and Vel Index (p=0.001), as shown in Figure 3. Other characteristics, namely LT (min) and StartTail (min), were not statistically significant, Table 3. The thrombin generation curve characteristics were further assessed to determine if there were any associations between them and the clinical characteristics associated with the development of VTE including ISS, surgery within 24 hours, and blood transfusion within 24 hours (Tables 4–6). Correlation analysis between ISS and the thrombin generation parameters revealed no significant associations. Lag time (p=0.010) and time to peak (p=0.016) were significantly shorter in patients who had surgery within 24 hours of injury than in those who did not. Time to peak (p=0.010) was also significantly shorter in those who received blood products within 24 hours of injury. Peak height, ETP, and Vel Index were not significantly different across the groups of patients who did and did not undergo surgery or receive transfusions.
Figure 3: Characteristics of thrombin generation profiles in VTE patients compared to non-VTE patients.
Legend: Comparison of measured key thrombin generation assay parameters between trauma patients developing venous thromboembolism (VTE) (n= 64) and those who did not develop VTE (n=190). VTE, venous thromboembolism.
Table 3:
Characteristics of Thrombin Generation Profiles in VTE patients compared to non-VTE patients.
| VTE (n = 63) | Non-VTE (n = 161) | p-value | |
|---|---|---|---|
| Start Tail (min) | 17.56 [16.37, 19.44] | 17.76 [16.05, 19.49] | 0.96 |
| LT (min) | 2.78 [2.48, 3.32] | 2.99 [2.63, 3.41] | 0.075 |
| Peak Height (nM) | 281.3 [248.8, 345.5] | 256.5 [194.1, 298.8] | 0.002 |
| ttPeak (min) | 4.95 [4.39, 5.66] | 5.30 [4.78, 6.06] | 0.027 |
| ETP (nM*min) | 1474 [1324, 1781] | 1324 [1135, 1544] | 0.001 |
| Vel Index (nM/min) | 180.9 [126.6, 241.6] | 147.6 [97.4, 195.5] | 0.003 |
Characteristics of thrombin generation profiles in patients developing venous thromboembolism (VTE) compared to patients that did not develop VTE. LT = LagTime= time to start of curve, Start Tail (min) = overall time to initiation of the tail of thrombin generation curve, ttPeak = time to peak, ETP = endogenous thrombin potential, Vel Index = velocity index. Results presented as median with quartiles [Q1, Q3]. Wilcoxon rank-sum test for difference between groups. P-value < 0.05 significant.
Table 4:
Associations Between Thrombin Generation Curve Characteristics and Clinical Risk Factors of VTE
| a. ISS vs. Thrombin Generation Curve Characteristics | ||
|---|---|---|
| Spearman Correlation Coefficient | p-value | |
| LT (min) | −0.065 | 0.33 |
| Peak Height (nM) | 0.026 | 0.69 |
| ttPeak (min) | −0.132 | 0.046 |
| ETP (nM * min) | −0.027 | 0.69 |
| Velocity Index (nM / min) | 0.118 | 0.075 |
| Start Tail (min) | 0.039 | 0.56 |
| b. Surgery within 24 hours vs. Thrombin Generation Curve Characteristics | |||
|---|---|---|---|
| No surgery within 24 hours of injury (n=121) | Surgery within 24 hours of injury (n=133) | p-value | |
| LT (min) | 3.09 [2.69, 3.47] | 2.83 [2.52, 3.33] | 0.010 |
| Peak Height (nM) | 262.6 [206.5, 310.6] | 263.2 [212.9, 318.9] | 0.85 |
| ttPeak (min) | 5.36 [4.87, 6.16] | 5.06 [4.52, 5.75] | 0.016 |
| ETP (nM * min) | 1361 [1165, 1597] | 1381 [1142, 1587] | 0.97 |
| Velocity Index (nM / min) | 148.4 [101.1, 205.4] | 157.5 [110.7, 218.0] | 0.33 |
| Start Tail (min) | 17.6 [16.0, 19.3] | 17.9 [16.3, 19.6] | 0.40 |
| c. Blood Transfusion within 24 hours vs. Thrombin Generation Curve Characteristics | |||
|---|---|---|---|
| No transfusion within 24 hours of injury (n=170) | Transfusion within 24 hours of injury (n=84) | p-value | |
| LT (min) | 3.00 [2.63, 3.39] | 2.76 [2.55, 3.35] | 0.061 |
| Peak Height (nM) | 262.8 [205.5, 311.4] | 266.0 [224.9, 319.3] | 0.63 |
| ttPeak (min) | 5.33 [4.84, 6.10] | 4.95 [4.44, 5.65] | 0.010 |
| ETP (nM * min) | 1348 [1141, 1588] | 1417 [1237, 1617] | 0.15 |
| Velocity Index (nM / min) | 151.3 [101.2, 208.4] | 160.3 [119.0, 230.2] | 0.093 |
| Start Tail (min) | 17.5 [15.9, 19.0] | 18.2 [16.4, 20.2] | 0.031 |
DISCUSSION:
This study is the first to document the use of a platform assessment of thrombin generation assays for trauma patients based on batch processing. Our research confirms with a platform-based assessment of thrombin generation profiles of trauma patient samples, similar to as reported previously from prior studies, that accelerated thrombin generation profiles are observed in the plasma of VTE trauma patients than in those without VTE.4
Existing literature outlines that post-traumatic injury results in early and sustained thrombin generation, which may contribute to a sustained prothrombotic risk and eventual development of VTE days to months after injury.13–16 This may result from an ongoing vascular endothelial inflammation after traumatic injury resulting from tissue injury, resulting in activated platelets, neutrophil and macrophage related activity, and cytokine release, resulting in a sustained thromboinflammatory state well after initial injury.17–19 Furthermore, thrombin generated excessively in the early hours of injury not only facilitates fibrin formation and crosslinking in a clot, but also injures endothelial cells. The endothelial injury initiates and propagates intrinsic coagulation on the surface of endothelial cells and causes thrombotic injury to the vessel wall, resulting in persistent fibrin deposition to the endothelium, which is a hallmark of venous thrombosis.
Further analysis showed that several thrombin generation parameters, in particular peak thrombin generation as quantified by Peak Height and overall thrombin generation as quantified by ETP, appear to be independent of severity of injury as quantified by ISS and surgical intervention within 24 hours. This merits further investigation by way of a broader multivariable VTE risk model that incorporates readily obtainable clinical risk factors with individual patient’s plasma coagulome as reflected by platform TGA parameters. Indeed, the ST Genesia platform-based TGA appears well-suited to identify accelerated thrombin generation. Given that it measures thrombin generation in a standardized manner and requires more limited laboratory handling, it may be better placed than its predecessor, CAT, to compare data between laboratories and institutions. As Ninivaggi et al. outlines, the ST Genesia use of a reference plasma enables normalization of data and provides a level of quality control enabling comparison between institutions and laboratories.8 Furthermore, with relatively minor modifications of its standard protocol, it can run a higher volume of patient samples at a given time, with more than 10 patient samples able to run within a given batch run. While analytical variation between reagent lots was not noted within our study, lot-based variability should be considered, with a similar variation to that of CAT, as noted by Kristensen et al.6
Our results, combined with prior published literature by Park et al, confirm the findings that dysregulation of the thromboinflammatory pathway appears to contribute to increased risk of VTE after injury, now shown in this platform TGA.4 The insult of trauma results in a quantifiable change to the patient plasma coagulome profile as reflected in the patient-specific thrombin generation curve assessed with a platform TGA, which has the advantage of ease of operator use and normalization of data. Furthermore, this may portend increased utility and functionality for incorporation in a translational risk tool to be used by clinicians to identify patients at high risk of VTE early after traumatic injury.
Our study has several limitations. This is a sub-study of a multi-center, prospective case-cohort study predominantly involving patients with blunt trauma, and hence the generalizability of our findings is limited at this time.
Additionally, we analyzed samples collected early after injury and will need to observe longer-term trends in the thromboinflammatory process as the development of VTE occurs, and thus samples collected at a broad range of time points will need to be evaluated. Furthermore, time variability of the samples drawn for individual patients can be evaluated to characterize the trajectory of thrombin generation profiles between patients and explore the assumption that early samples are equally predictive using the ST Genesia platform as found with the CAT platform.4,16
The impact of blood transfusions merits additional exploration, as transfusions may alter thrombin generation kinetics, secondary to bleeding and hemodilution.20,21,22 While prior studies have compared CAT vs ST Genesia based thrombin generation parameters in healthy volunteers7, to our knowledge, there has not been a correlation study evaluating the comparison of the two assays in trauma patients and this is an area for further study. Furthermore, this study did not evaluate the platform in comparison with healthy volunteers; while reference ranges for healthy volunteers in the ST Genesia platform have been reported in literature, further standardization of the platform among populations would increase clinical utility.7,8 Also of note, the risk profiles and characteristics of patients developing symptomatic VTE and asymptomatic VTE may differ, and this study did not seek to capture asymptomatic VTE trauma patients in terms of screening, and this may limit applicability to symptomatic trauma patients. The ratio of DVT:PE reported within the VTE trauma patients in this study was ~1:1, and we note that our trauma population does report a greater age and pre-traumatic comorbidity burden compared to other large epidemiological studies.23,24 This approach is based on Institution guidelines and protocols, including those outlined by the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines and the American Society of Hematology.25,26,27 In the future, our goal is to combine clinical and thrombin characteristics of trauma patients to provide a personalized VTE prediction using multivariable modeling. We are also currently evaluating other thromboinflammatory biomarkers, which is outside the scope of discussion in this current manuscript. Further work will evaluate the adoption and potential benefit of such as tool to guide thromboprophylaxis decision making to individualize care and reduce both the under-and overtreatment of trauma patients. Lastly, while we did not observe lot variability in this study due to using a single lot of reagent; however, there may be a variability noted with future lot-to-lot changes of reagents and further standardization of reagents may be needed. That said, lot to lot reagent variability has been reported to be similar to that reported within acceptable ranges previously for CAT.7,8
CONCLUSION:
Using this novel TGA platform, we found that trauma patients who develop VTE exhibit accelerated thrombin generation early after injury, compared to trauma patients who do not. It has the potential to rapidly identify patients at high risk of VTE via batch testing, enabling a translational tool to provide an individualized VTE risk assessment, pending further external validation.
Supplementary Material
Acknowledgments:
The authors gratefully acknowledge the Clinical Research Unit (CRU) of the Center for Translational Science Activities (CTSA) at Mayo Clinic for their 24-hour support in sample collection. We are grateful for the technical assistance received from Paul Riley and Diptesh Patel from ST Genesia for sample analysis.
Funding:
This study was supported by R38HL150086 (SMN), R01HL162729-02(MSP), and UL1 TR002377 (MSP) from the National Center for Advancing Translational Sciences (NCATS). The contents are the sole responsibility of the authors and do not necessarily represent the official views of the National Institute of Health (NIH).
Footnotes
Conflict of Interest: JTACS COI Disclosure forms for all authors have been supplied and are provided as supplemental digital content (SDC1).
Meeting Presentation: This paper was presented at the EAST Conference in Tucson, Arizona as an oral podium presentation, January 14–18, 2025, and will be considered for the Raymond H Alexander Resident Paper Competition Award.
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