Temporal Changes in Serum S100B Levels From Prehospital to Early In-Hospital Sampling in Patients Suffering Traumatic Brain Injury.

Background: The biomarker S100B is used for the rule-out of intracranial lesions in patients with mild traumatic brain injury (TBI) and is suggested for prehospital use in Europe. Early kinetics of S100B are not exhaustively investigated in human TBI. This post hoc descriptive study of the data from the PreTBI studies aimed to characterize the early temporal changes of S100B using two-sample timepoints. Materials and Methods: Two consecutive blood samples were taken prehospital and in-hospital after injury and assayed for S100B. The endpoint adjudication of the outcome intracranial lesion was done by the evaluation of electronic medical patient journals. The data were analyzed using descriptive statistics, scatterplots, and temporal changes estimated by the locally weighted scatterplot smoothing (LOWESS) regression line. Results: A total of 592 adult patients with TBI were included; 566 with Glasgow Coma Scale (GCS) 14-15, 20 with GCS 9-13, and 6 with GCS 3-8. Intracranial lesions were diagnosed in 44/566 (7.4%) of patients. In 90% of patients, S100B concentrations decreased from prehospital to in-hospital sampling. The mean decrease was-0.34 µg/L. S100B concentrations seem to decline already within 60 min. Patients sampled very close to trauma and patients suffering intracranial lesions may express a slight incline before this decline. Temporal changes of S100B did not differ in patients >65 years of age, in antiplatelet/-coagulant treatment, alcohol intoxicated, or suffering extra-cranial injuries. Conclusion: S100B concentrations may peak earlier than expected from previous studies of temporal changes in human TBI. Patterns of S100B stand robust to parameters stated as limiting factors to the use for early rule-out of intracranial lesions in the current guidelines. Further studies are needed to investigate the ultra-early temporal profiles of other novel TBI biomarkers to assess prehospital applicability and optimal diagnostic performance in TBI.

Diagnostic accuracy of prehospital serum S100B and GFAP in patients with mild traumatic brain injury: a prospective observational multicenter cohort study - "the PreTBI I study".

BACKGROUND: The biomarker serum S100 calcium-binding protein B (S100B) is used in in-hospital triage of adults with mild traumatic brain injury to rule out intracranial lesions. The biomarker glial fibrillary acidic protein (GFAP) is suggested as a potential diagnostic biomarker for traumatic brain injury. The aim of this study was to investigate the diagnostic accuracy of early prehospital S100B and GFAP measurements to rule out intracranial lesions in adult patients with mild traumatic brain injury. METHODS: Prehospital and in-hospital blood samples were drawn from 566 adult patients with mild traumatic brain injury (Glasgow Coma Scale Score 14-15). The index test was S100B and GFAP concentrations. The reference standard was endpoint adjudication of the traumatic intracranial lesion based on medical records. The primary outcome was prehospital sensitivity of S100B in relation to the traumatic intracranial lesion. RESULTS: Traumatic intracranial lesions were found in 32/566 (5.6%) patients. The sensitivity of S100B > 0.10 µg/L was 100% (95%CI: 89.1;100.0) in prehospital samples and 100% (95% CI 89.1;100.0) in in-hospital samples. The specificity was 15.4% (95%CI: 12.4;18.7) in prehospital samples and 31.5% (27.5;35.6) in in-hospital samples. GFAP was only detected in less than 2% of cases with the assay used. CONCLUSION: Early prehospital and in-hospital S100B levels < 0.10 µg/L safely rules out traumatic intracranial lesions in adult patients with mild traumatic brain injury, but specificity is lower with early prehospital sampling than with in-hospital sampling. The very limited cases with values detectable with our assay do not allow conclusions to be draw regarding the diagnostic accuracy of GFAP. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02867137 .

Influence of Simulated Pre-Hospital Transport, Time to Analysis, and Storage Temperature on S100 Calcium-Binding Protein B Values.

According to in-hospital guidelines, the biomarker, S100 calcium-binding protein B (S100B), is used to rule out intracranial lesions in mild-moderate traumatic brain injury (TBI). It is currently investigated whether S100B is applicable in a pre-hospital setting. The aim was to compare S100B values and hemolysis index in blood samples drawn and stored under simulated pre-hospital conditions to standardized blood samples. Thirty patients undergoing craniotomy at Department of Neurosurgery, Aarhus University Hospital (Aarhus, Denmark) each had six blood samples drawn. Two samples, drawn in in-hospital standardized Beckton Dickinson tubes and pre-hospital Monovette tubes, respectively, were stored as references at 21°C for 30 min. Two samples were stored at 15°C and 29°C, respectively, one sample was stored at prolonged time (60 min), and one sample was transported for 30 min before centrifugation. S100B values were compared by equivalence test with a pre-defined equivalence margin of ±8.5%. There was no clinically relevant difference between samples stored in different tubes, at various temperatures, or time to analysis compared to reference samples. Transported samples had an 11.5% (90% confidence interval [CI], 6.55; 16.61) higher median S100B value and a 430% (95% CI, 279.6; 661.4) higher median hemolysis index compared to reference samples. Three of 30 (10%) patients had an S100B value above guideline cutoff in the transported sample, which was not found in reference samples (false positive). There were no false negatives. In conclusion, S100B values were not influenced by different tubes, temperatures, and time to analysis. Transported samples had higher median S100B values and hemolysis, icterus, and lipemia index compared to reference samples.