The Scandinavian Guidelines for Initial Management of Minimal, Mild, and Moderate Head Injuries in Adults (Scandinavian guidelines) are the first to incorporate serum measurement of the S100 astroglial calcium-binding protein B (S100B) to emergency department (ED) triage of patients with head injury (HI). This prospective validation study was conducted in the ED of the Tampere University Hospital, Finland, between November 2015 and November 2016. All consecutive adult patients with HI presenting to the ED within 24 h from injury were eligible for inclusion. Venous blood for S100B sampling was drawn from all patients, and the result was available at the ED. Computed tomography (CT) scans of the head were performed according to the on-call physician's evaluation. Only the samples collected within 6 h after injury were used. A one-week follow-up was conducted to identify possible HI-related complications. A total of 295 patients (median age, 67.0 years, range, 18-100; women, 48.8%) were enrolled. Of those, 196 (66.4%) underwent scanning. Acute traumatic lesions were detected on 31 (15.8%) of the scans. Two of the CT-positive patients were scanned without a guidelines-based indication. These lesions did not require any specific treatment or repeated imaging. The guidelines-based sensitivity was 0.94 (95% confidence interval [CI], 0.77-0.99) and specificity 0.19 (95% CI, 0.13-0.26) for predicting traumatic intracranial CT abnormalities. The positive and negative predictive value for positive head CT was 0.18 (95% CI, 0.12-0.25) and 0.94 (95% CI, 0.78-0.99), respectively. In the mild-low risk group, no false negative S100B values were recorded. Thirteen patients (4.4%) were re-admitted to the ED, and two patients (0.7%) died one week after the primary HI. The deaths were unrelated to the injury. None of these adverse events were directly caused by a primarily undiagnosed intracranial injury. The Scandinavian guidelines incorporated with S100B are a valid means of screening clinically significant acute traumatic lesions after HI and have the potential to reduce unnecessary CT scanning.
Keywords: brain injury; computed tomography; emergency treatment; guideline; head injury.