S-100β protein-serum levels in healthy children and its association with outcome in pediatric traumatic brain injury

Objective: To describe normal serum levels of S-100β in healthy children and determine whether serum S-100β levels after traumatic brain injury are associated with outcome. Design: Prospective cohort study. Setting: Urban, tertiary care, children's teaching hospital. Patients: A total of 136 healthy children and 27 children with traumatic brain injury. Methods: Serum S-100β levels were measured in 136 healthy children. A total of 27 children with traumatic brain injury had S-100β levels collected within 12 hrs of injury. Other indices of severity of injury measured were admission Glasgow Coma Scale score, and Pediatric Risk of Mortality score at 24 hrs (PRISM 24). Outcome was measured by the Pediatric Cerebral Performance Category (PCPC) score at hospital discharge and 6 months postinjury or at death. Measurements and Main Results: S-100β levels in healthy children had a mean of 0.3 μg/L (90% confidence interval, 0.03-1.47) and inversely correlated with age, (r = -.32, p < .001). In children with traumatic brain injury, 6-month postinjury outcome inversely correlated with Glasgow Coma Scale score (r = -.47, p = .01) and correlated with PRISM 24 score (r = .83, p < .001) and S-100β levels (r = .75, p < .001). Six months postinjury, comparing good outcome (PCPC ≤ 3, n = 20) vs. poor outcome (PCPC ≥ 4, n = 7), median admission Glasgow Coma Scale scores were 8 (range, 3-15) and 3 (range, 3-7, p = .01), median PRISM 24 scores were 7 (range, 0-19) and 30 (range, 18-35, p < .001), and median S-100β levels were 0.85 μg/L (range, 0.08-4.8 μg/L) and 3.6 μg/L (range, 1.4-20 μg/L, p < .001), respectively. A serum S-100β level of >2.0 μg/L is associated with poor outcome, with a sensitivity of 86% and a specificity of 95%. The area under the receiver operating curve for S-100β was 0.94 (±0.05). Conclusions: Serum S-100β levels in healthy children have a moderate inverse correlation with age. After traumatic brain injury in children, the acute assessment of serum S-100β levels seems to be associated with outcome.