Computed tomography findings in 11,504 adult patients with traumatic brain injury: a large real-world cohort study with a S100B subgroup analysis

OBJECTIVE: The aim of this study was to characterize acute cranial CT findings in a large cohort of adult patients with traumatic brain injury and to explore the diagnostic performance of S100B in a selected subgroup. The hypothesis was that most cranial CT scans in adult patients with traumatic brain injury would not demonstrate acute traumatic abnormalities, and that, within a selected subgroup, negative S100B levels would be associated with the absence of such findings on CT. METHODS: This retrospective cohort study included 11,504 adult patients presenting with traumatic brain injury to a level I trauma center between 04/2016 and 05/2024. All patients underwent cranial CT, while serum S100B measurements were available in a selected subset. CT findings were classified as normal or showing acute traumatic abnormalities. In the S100B subgroup, biomarker levels were analyzed in relation to CT findings to assess their diagnostic performance for excluding acute pathology. RESULTS: A total of 11,504 adult patients with traumatic brain injury were included; 27.4% were inpatients and 72.6% outpatients. Overall, 81.9% of CT scans showed no acute pathology, while 10.7% demonstrated abnormalities. 7.4% of all cases were excluded. Acute TBI-related interventions were rare (3.7% of inpatients vs. 0.3% of outpatients). In patients with dementia and those receiving anticoagulation, CT scans remained normal in 81.7% and 81.9%, respectively. S100B was available in 483 patients (4.2%); negative values were associated with absence of CT pathology, with higher negative predictive value in outpatients (98%) than in inpatients (73%) (p < 0.001). CONCLUSION: In this large retrospective cohort of adult patients with traumatic brain injury, most cranial CT examinations were negative for acute pathology. In a selected subgroup, negative S100B levels were associated with the absence of CT abnormalities, with substantially lower performance in inpatients. These findings suggest a potential adjunctive role of S100B in selected low-risk patients, however further prospective studies with standardized testing protocols are required to define the diagnostic utility and clinical applicability of S100B more precisely in the evaluation of traumatic brain injury.