Clinical validation of S100B in the management of a mild traumatic brain injury: issues from an interventional cohort of 1449 adult patients

Background: This study's primary objective was to validate the routine use of S100B via a prospective study. The aim was a reduction of cranial computed tomography (CCT) scans by 30%. The secondary goal was to investigate the influence of age and associated risk factors on the reduction of CCT. Methods: S100B (sampling within 3 h postinjury) was used for patients with mild traumatic brain injury (mTBIs) presenting a medium risk of complications and requiring a CCT scan. Patients with negative S100B (S100B-) were discharged without a CCT scan. Results: Of the 1449 patients included in this study, 468 (32.3%) had S100B-with a sensitivity of 96.4% (95% CI: 87.5%-99.6%), a specificity of 33.4% (95% CI: 31%-36%) and a negative predictive value of 99.6% (95% CI: 98.5%-99.9%). No significant difference in serum levels or the S100B+ rate was observed if patients had retrograde amnesia (0.16 mu g/L; 63.8%), loss of consciousness (0.13; 63.6%) or antiplatelet therapy (0.20; 77.9%). Significant differences were found between the S100B concentrations and S100B positivity rates in patients > 65 years old and all the groups with patients < 55 years old (18-25, 26-35, 36-45 and 46-55). From 18 to 65 years old (n = 874), the specificity is 39.3% (95% CI: 36%-42.6%) compared to 18.7% (95% CI: 15.3%-22.3%) for patients > 65 years old (n = 504). Conclusions: The clinical use of S100B in mTBI management reduces the use of CCTs by approximately one-third; furthermore, the percentage of CCTs reduction is influenced by the age of the patient.