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.

The microINR portable coagulometer: analytical quality and user-friendliness of a PT (INR) point-of-care instrument.

Regular measurement of prothrombin time as an international normalized ratio PT (INR) is mandatory for optimal and safe use of warfarin. Scandinavian evaluation of laboratory equipment for primary health care (SKUP) evaluated the microINR portable coagulometer (microINR®) (iLine Microsystems S.L., Spain) for measurement of PT (INR). Analytical quality and user-friendliness were evaluated under optimal conditions at an accredited hospital laboratory and at two primary health care centres (PHCCs). Patients were recruited at the outpatient clinic of the Laboratory of Medical Biochemistry, St Olav's University Hospital, Trondheim, Norway (n = 98) and from two PHCCs (n = 88). Venous blood samples were analyzed under optimal conditions on the STA-R®Evolution with STA-SPA + reagent (Stago, France) (Owren method), and the results were compared to capillary measurements on the microINR®. The imprecision of the microINR® was 6% (90% CI: 5.3-7.0%) and 6.3% (90% CI: 5.1-8.3) in the outpatient clinic and PHCC2, respectively for INR ≥2.5. The microINR® did not meet the SKUP quality requirement for imprecision ≤5.0%. For INR <2.5 at PHCC2 and at both levels in PHCC1, CV% was ≤5.0. The accuracy fulfilled the SKUP quality goal in both outpatient clinic and PHCCs. User-friendliness of the operation manual was rated as intermediate, defined by SKUP as neutral ratings assessed as neither good nor bad. Operation facilities was rated unsatisfactory, and time factors satisfactory. In conclusion, quality requirements for imprecision were not met. The SKUP criteria for accuracy was fulfilled both at the hospital and at the PHCCs. The user-friendliness was rated intermediate.

Marinimicrobium haloxylanilyticum sp. nov., a new moderately halophilic, polysaccharide-degrading bacterium isolated from Great Salt Lake, Utah.

A new moderately halophilic, strictly aerobic, Gram-negative bacterium, strain SX15(T), was isolated from hypersaline surface sediment of the southern arm of Great Salt Lake (Utah, USA). The strain grew on a number of carbohydrates and carbohydrate polymers such as xylan, starch, carboxymethyl cellulose and galactomannan. The strain grew at salinities ranging from 2 to 22% NaCl (w/v). Optimal growth occurred in the presence of 7-11% NaCl (w/v) at a temperature of 35°C and a pH of 6.7-8.2. Major whole-cell fatty acids were C16:0 (30.5%), C18:0 (14.8%), C18:1ω7c (13.1%) and C12:0 (7.8%). The G+C content of the DNA was 60 ± 0.5 mol%. By 16S rRNA gene sequence analysis, strain SX15(T) was shown to be affiliated to members of the gammaproteobacterial genus Marinimicrobium with pair wise identity values of 92.9-94.6%. The pheno- and genotypic properties suggest that strain SX15(T) represents a novel species of the genus Marinimicrobium for which the name Marinimicrobium haloxylanilyticum is proposed. The type strain is SX15(T) (= DSM 23100(T) = CCUG 59572(T)).