Ethnic Specificities of S100B Protein Blood Level in Guadeloupe: Cross-sectional Study in Healthy Subjects

Overview

Numerous studies have demonstrated the significant contribution of S100B blood level measurement in the management of minor to moderate traumatic brain injuries, notably by reducing the number of cranial computed tomography (CT) scans by at least one-third. However, physiological blood concentrations of the S100B protein may be higher in individuals with a Black phenotype compared to those with Asian or, in particular, Caucasian phenotypes. Assessing S100B protein levels in healthy individuals will help confirm the variability of its physiological concentration according to skin phenotype.

Thanks to its excellent negative predictive value, the S100B protein has been defined as a reliable alternative to computed tomography (CT) in the management of traumatic brain injury (TBI). Validated by scientific societies in 2014, the use of this biomarker could reduce the number of cerebral CT scans by nearly one-third in cases of minor TBI. However, implementation of this blood test in routine clinical practice may present challenges. The extrapolation of findings from S100B studies to the context of Guadeloupe remains uncertain. The commonly accepted threshold of 0.1 μg/L for S100B protein, used to determine the need for CT imaging, has been established based on existing literature. Nevertheless, the study by Abdesselam (Clinical Chemistry 49, No. 5, 2003) suggests that S100B concentrations may vary by ethnic background: higher levels have been observed in individuals of Black phenotype (0.14 ± 0.08 μg/L) compared to those of Asian (0.11 ± 0.08 μg/L) and Caucasian (0.07 ± 0.03 μg/L) phenotypes. A closer analysis of Abdesselam's data reveals that approximately three-quarters of individuals with a Black phenotype may present physiological S100B levels exceeding 0.1 μg/L. Given that the majority of Guadeloupe's population is of Black phenotype, applying the 0.1 μg/L threshold for CT scan decision-making may lack accuracy for this population. Nonetheless, Abdesselam's study involved a limited sample size (46 individuals of Black ethnicity) and showed high interindividual variability in S100B levels. Further validation is therefore required in Guadeloupe and, more broadly, in Caribbean populations. The planned study will enroll hospital staff who meet predefined eligibility criteria. Prior to inclusion, eligible individuals will receive an information leaflet and consent form, both explained by a physician or a clinical research nurse. Upon obtaining signed informed consent, each subject will complete an anonymous questionnaire detailing ethnic background, age, sex, and weight. A blood sample will then be collected and sent to the biochemistry laboratory at the University Hospital of Guadeloupe for S100B protein analysis.