Clinical validation of S100B use in management of mild head injury

Background Despite validated guidelines, management of mild head injury (MHI) is still associated with excessive computed tomography (CT) scanning. Reports concerning serum levels of S100B have shown promise concerning safe reduction in CT scanning but clinical validation and actual impact on patient management is unclear. In 2007, S100B was introduced into emergency department (ED) clinical management routines in Halmstad, Sweden. MHI patients with low (<0.10 mikrogram/L) levels of S100B could be discharged without CT. Our aim was to examine the clinical impact and performance of S100B in clinical use for MHI patients. Methods Adult ([≥]18 years) patients with MHI (GCS 14–15, loss of consciousness and/or amnesia and no additional risk factors) and S100B sampling within 3 hours were prospectively included in this validation study. Patients were managed according to the adapted guidelines and management was documented. Outcome was determined with a questionnaire 3 months post-trauma and medical records to identify significant intracranial complications such as new neuroimaging, neurosurgery and/or death related to the trauma. Results 512 patients were included. 24 (4.7%) showed traumatic abnormalities on CT and 1 patient died (0.2%). 138 patients (27%) had normal S100B levels and 374 patients (73%) showed elevated S100B levels. No patients with a normal S100B level showed significant intracranial complication. 44 patients (32%) were managed with CT despite the guidelines recommending discharge (all these CT scans were normal) and 28 patients (7%) were discharged despite a CT recommendation (follow-up was normal in all these patients). S100B had a sensitivity of 100% (95% CI 83-100%) and a specificity of 28% (95% CI 24-33%) for significant intracranial complications. Conclusion The clinical use of S100B within our existing guidelines for management of MHI is safe and effective. Adult MHI patients, without additional risk factors and with normal S100B levels within 3 hours of injury, can safely be discharged from the hospital.