Background: Glial Fibrillary Acidic Protein (GFAP) and Ubiquitin C-terminal hydrolase (UCH-L1) have been FDA-approved in adults to guide CT scan ordering but their ability to detect concussion in children or adults has not been determined. This study evaluated the diagnostic accuracy of GFAP and UCH-L1 to distinguish concussive versus non-concussive head and body trauma in pediatric and adult trauma patients with normal mental status (GCS Score 15).
Methods: This large prospective cohort study enrolled pediatric and adult trauma patients presenting to 3 Level 1 Trauma Centers within 4 hours of injury. All patients underwent rigorous screening to determine presence of concussion using a standardized definition. In adults, repeated blood sampling was conducted at 4, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168 and 180 hours post-injury. Control groups included trauma patients without concussion with head (head trauma control) or body trauma (body trauma control). Data is in means and AUC with 95%CIs.
Results: Of 3462 trauma patients screened, 712 were enrolled and a total of 1904 samples were drawn. Both GFAP and UCH-L1 were lowest in body trauma GFAP=0.021 (0.017-0.024)/UCH-L1=0.290 (0.242-0.337), and increased incrementally in non-concussive head trauma GFAP=0.051 (0.038-0.064)/UCH-L1=0.507 (0.382-0.633), with highest levels in concussion GFAP=0.241 (0.184-0.299)/UCH-L1=0.776 (0.647-0.904). AUC for GFAP for detecting concussive injury within 4 hours of injury in adults was 0.76 (0.71-0.80) and in children 0.80 (0.73-0.87). AUC for UCH-L1 was 0.69 (0.64-0.74) in adults and 0.62 (0.53-0.72) in children. GFAP demonstrated a diagnostic range of AUC’s for distinguishing concussion from body trauma of 0.75 to 0.89 and UCH-L1 0.54 to 0.78 over 7 days. For distinguishing concussive vs non-concussive head trauma the range of AUC’s for GFAP was 0.62 to 0.86 and for UCH-L1 0.13 to 0.61.
Conclusion: GFAP levels were negligible in both non-concussive control groups but UCH-L1 levels were elevated in both control groups. GFAP out-performed UCH-L1 in distinguishing concussion from both head and body trauma without concussion within 4 hours of injury in both children and adults. Mild elevations of both biomarkers in patients with head trauma without concussion may be reflective of subconcussive injury but its significance requires further study.