Data from: Tau protein as a diagnostic marker for diffuse axonal injury

Background: Diffuse axonal injury (DAI) is difficult to identify in the
early phase of traumatic brain injury (TBI) using common diagnostic
methods. Tau protein is localized specifically in nerve axons. We
hypothesized that serum level of tau can be a useful biomarker to diagnose
DAI in the early phase of TBI. Methods & Results: We measured
serum tau levels in 40 TBI patients who were suspected of DAI within 6
hours after TBI to evaluate the accuracy of the tau level as a diagnostic
marker for DAI. Diagnosis of DAI was confirmed according to magnetic
resonance imaging (MRI) findings. The serum tau level in the DAI group
(n=13) was significantly higher than that in the non-DAI group (n=27) (DAI
vs. non-DAI, 25.3 [0 to 99.1] pg/mL vs. 0 [0 to 44.4] pg/mL, P=0.03)). A
receiver-operating characteristic curve to evaluate the diagnostic ability
of serum tau level within 6 hours for DAI showed an area under the curve
of 0.690 with 74.1% for sensitivity and 69.2% for specificity. Serum tau
level was not significantly higher in unfavorable outcome group (Glasgow
Outcome scale [GOS] score=1-3 at hospital discharge) compared with
favorable outcome group (GOS score=4-5) (P=0.19). Conclusions: Tau protein
may be a useful biomarker for diagnosis of DAI in the early phase of TBI.