Lack of association between four biomarkers and persistent post-concussion symptoms after a mild traumatic brain injury.

Approximately 15 % of individuals who sustained a mild Traumatic Brain Injury (TBI) develop persistent post-concussion symptoms (PPCS). We hypothesized that blood biomarkers drawn in the Emergency Department (ED) could help predict PPCS. The main objective of this project was to measure the association between four biomarkers and PPCS at 90 days post mild TBI. We conducted a prospective cohort study in seven Canadian EDs. Patients aged ≥ 14 years presenting to the ED within 24 h of a mild TBI who were discharged were eligible. Clinical data and blood samples were collected in the ED, and a standardized questionnaire was administered 90 days later to assess the presence of symptoms. The following biomarkers were analyzed: S100B protein, Neuron Specific Enolase (NSE), cleaved-Tau (c-Tau) and Glial Fibrillary Acidic Protein (GFAP). The primary outcome measure was the presence of PPCS at 90 days after trauma. Relative risks and Areas Under the Curve (AUC) were computed. A total of 595 patients were included, and 13.8 % suffered from PPCS at 90 days. The relative risk of PPCS was 0.9 (95 % CI: 0.5-1.8) for S100B ≥ 20 pg/mL, 1.0 (95 % CI: 0.6-1.5) for NSE ≥ 200 pg/mL, 3.4 (95 % CI: 0.5-23.4) for GFAP ≥ 100 pg/mL, and 1.0 (95 % CI: 0.6-1.8) for C-Tau ≥ 1500 pg/mL. AUC were 0.50, 0.50, 0.51 and 0.54, respectively. Among mild TBI patients, S100B protein, NSE, c-Tau or GFAP do not seem to predict PPCS. Future research testing of other biomarkers is needed to determine their usefulness in predicting PPCS.