Diagnostic Value of Serum S100B Protein in Anticoagulated Patients Admitted to the Emergency Department for Mild Traumatic Brain Injury

Background Mild traumatic brain injury (mTBI) is a common reason for emergency department visits. Its incidence is increasing, particularly among elderly individuals, who are often receiving anticoagulant therapy. Objective The aim of our study was to evaluate the diagnostic performance of serum S100B protein in anticoagulated patients admitted to the emergency department for mTBI. Methods We conducted a retrospective, single-center, observational study from January 1, 2014, to August 15, 2022, at the Emergency Department of Clermont-Ferrand University Hospital. We included all patients aged over 18 years who presented with mTBI, were on anticoagulant therapy, and underwent both S100B testing and a brain CT scan. Results Among the 46 patients included, 8 (17.4%) had an S100B level < 0.10 µg/L. Three patients (6.5%) experienced an intracranial hemorrhagic event; all had S100B levels > 0.10 µg/L. At a threshold of 0.10 µg/L, S100B showed a sensitivity of 100% (95% CI: 29.2–100), specificity of 93% (95% CI: 80.9–98.5), positive predictive value of 50% (95% CI: 11.8–88.2), and negative predictive value of 100% (95% CI: 91.2–100). The area under the ROC curve was 0.94 (95% CI: 86.67–100). Conclusion S100B protein shows promising and robust diagnostic value for evaluating the risk of intracranial bleeding in anticoagulated patients with mTBI. Further prospective studies with larger sample sizes are needed to confirm this hypothesis.