Glial and neuronal proteins in serum predict outcome after severe traumatic brain injury

Objective: To study the ability of glial ( glial fibrillary acidic protein [GFAP] and S100b) and neuronal ( neuron specific enolase [NSE]) protein levels in peripheral blood to predict outcome after severe traumatic brain injury. Methods: Eighty-five patients with severe traumatic brain injury ( admission Glasgow Coma Score [GCS] less than or equal to 8) were included. Blood samples taken at the time of hospital admission were analyzed for S100b, GFAP, and NSE. Data collected included demographic and clinical variables. Outcome was assessed using the Glasgow Outcome Scale (GOS) at 6 months post injury. Results: The median serum levels of S100b, GFAP, and NSE were raised 18.3 fold ( S100b), 4.6 fold ( GFAP), and twofold ( NSE) compared to normal reference values. S100b, GFAP, and NSE serum levels correlated significantly with the injury severity score and CT findings but not with age, sex, or GCS. S100b, GFAP, and NSE levels were significantly higher in patients who died or had a poor outcome 6 months post injury than in those who were alive or had good outcome. S100b level > 1.13 mug/L was the strongest predictor of death with 100% discrimination, but GFAP ( > 1.5 mug/L) and NSE ( > 21.7 mug/L) levels also strongly predicted death ( adjusted odds ratios 5.82 [ for GFAP] and 3.91 [ for NSE]). S100b, GFAP, and NSE all strongly predicted poor outcome ( adjusted odds ratios 5.12 [ S100b], 8.82 [ GFAP], and 3.95 [ NSE]). Conclusions: These results suggest that determination of serum levels of glial and neuronal proteins may add to the clinical assessment of the primary damage and prediction of outcome after severe traumatic brain injury.