Predicting outcome after severe traumatic brain injury using the serum S100B biomarker: results using a single (24h) time-point.

Background and Objectives: In recent years, biochemical markers have been employed to predict the outcome of patients with traumatic brain injury (TBI). In mild TBI, S100B has shown the most promise as a marker of outcome. The objective of this study in patients with severe TBI was to: show the range of serum S100B levels during the acute phase after trauma: determine if S100B has potential to discriminate favourable from unfavourable outcome in patients with similar brain injury severity scores and to establish an S100B 'cut-off' predictive for death.
Methods: All patients with severe TBI, admitted to this neurointensive care unit within 24h of injury were eligible for inclusion in the study. One serum blood sample was obtained from each patient at the 24h post-injury time-point. S100B levels were measured using enzyme-linked immunosorbent assay. Injuries were coded using an internationally recognised injury severity scoring system (ISS). Three-month follow-up was undertaken with outcome assessed using the Glasgow outcome score (GOS).
Results: One hundred patients were recruited. Serum S100B levels ranged from 0.08 to 12.62microgL(-1) S100B levels were significantly higher in patients with a GOS of 1 (death) 2 and 3 (unfavourable outcome) compared with those with GOS 4 and 5 (good recovery). In this study a cut-off point of 0.53microgL(-1) has sensitivity of >80% and specificity of 60% to predict unfavourable outcome and 49% to predict death.
Conclusion: In 100 patients studied with similar brain injury severity scores, serum S100B measured at the 24-h time-point after injury is significantly associated with outcome but a cut-off 0.53microgL(-1) does not have good prognostic performance.