S-100 B protein was identified as a biomarker for traumatic brain injury, but studies suggest that extracranial injuries may also lead to increased S-100 B serum levels. In this study, we aim to quantify the impact of injury patterns on S-100 B levels in patients with suspected multiple trauma. Patients with suspected multiple trauma treated at a Level 1 Trauma centre in Switzerland were included in this retrospective patient chart review. Extent of injuries and severity was assessed and S-100

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... levels on admission measured. Potential predictors of increased S-100 B levels (>0.2 µg/L) were identified through uni- and multivariable analyses. In total, 1,338 patients with suspected multiple trauma were included. Multivariable logistic regression showed a significant association with increased S-100 B levels in long bone fracture (OR 2.3, 95% CI: 1.3-4.1, p = 0.004), non-long bone fracture (OR 3.0, 95% CI: 2.2-4.3, p<0.001), thoracic injury (OR 2.6, 95% CI: 1.6-4.2, p<0.001), and deep tissue injury/wounds (OR 1.9, 95% CI: 1.4-2.6, p<0.001). Head trauma with intracerebral bleeding was only weakly associated (OR 2.0, 95% CI 1.2-3.5, p = 0.01) and head trauma without intracranial bleeding was not associated with an increased S-100 B protein level (p = 0.71). Trauma severity was also related to increased S-100 B levels (OR per ISS: 1.1, 95% CI 1.0-1.1, p<0.001). S-100 B levels <0.57 µg/L had a high diagnostic value to rule out in-hospital mortality (negative predictive value: 1.0, 95% CI: 0.98-1.00). Fractures and thoracic injuries appeared as main factors associated with increased S-100 B levels. Head injury may only play a minor role in S-100 B protein elevation in multiple trauma patients. A normal S-100 B has a good negative predictive value for in-hospital mortality. S100-B levels were associated with trauma severity and might thus be of use as a prognostic marker in trauma patients.