Tau Proteins in Serum Predict Outcome After Severe Traumatic Brain Injury

Background: The identification of reliable outcome predictors after traumatic brain injury (TBI) is crucial. The objective of our study was to investigate the role of tau protein as a serum marker of TBI.

Methods: Thirty-four patients with severe TBI (Glasgow Coma Scale [GCS] score at admission <or= 8) were considered. The tau protein level in the blood samples obtained at the time of admission was measured. The outcome was assessed by using the Glasgow Outcome Scale (GOS) at 6 mo post-injury. Demographic, clinical, and laboratory variables were analyzed to study their effect on the outcome.

Results: tau Protein levels were higher in the poor outcome group (436.2 +/- 473.6 pg/mL) than in the good outcome group (51.6 +/- 81.5 pg/mL) (P < 0.0001). Univariate analyses demonstrated that poor outcome was significantly associated with a poor GCS score (P = 0.001), higher serum tau protein levels (P < 0.001), abnormal pupil light reflex (P = 0.013), and basal cistern compression on computed tomogram (CT) (P = 0.026). Multivariate analyses revealed that a poor GCS score (P = 0.049) and higher serum tau protein levels (P = 0.043) were independent prognostic factors for poor outcome. The receiver-operating characteristic (ROC) curve demonstrated that a tau protein level >or= 114.5 pg/mL yielded 88% sensitivity and 94% specificity for predicting a poor outcome.

Conclusions: These results suggest that in addition to GCS; serum tau protein levels may serve as indicators for the prediction of outcome following severe TBI. However; it should be viewed with caution because of the small sample size and wide standard deviations.