720 - Whole blood GFAP and LCH-L1 for prediction of absence of intracranial injury on computed tomography in pediatrics

Publication Number: 3697.720

Megan McChesney, University of Nebraska Medical Center, Omaha, NE, United States; James F. Buscher, University of Nebraska College of Medicine, Omaha, NE, United States; Jessica Lee, Children's Hospital & Medical Center, Omaha, NE, United States; Patrick B. Thomas, Childrens nebraska, Omaha, NE, United States; Suzanne B. Haney, University of Nebraska College of Medicine, Omaha, NE, United States; Arnett Klugh, Children’s Nebraska, University of Nebraska Medical Center, Omaha, NE, United States; Christopher North, Childrens Nebraska PRIDE, Omaha, NE, United States; Zebulon Timmons, University of Nebraska College of Medicine, Elkhorn, NE, United States; Grace Lai, Childrens Nebraska, Omaha, NE, United States

Background: Glial fibrillary protein (GFAP) and c-terminalhydrolase-L1 (UCH-L1) are biomarkers used to predict negative head CT (HCT) scans for traumatic brain injury (TBI) in adults. There is limited data on how these tests perform in the pediatric population.

Objective: The purpose of the study is to determine the specificity of GFAP and UCH-L1 in a pediatric population. Our aim is to determine if these might be effective clinical biomarkers to obviate the need for HCT in children with blunt head trauma, avoiding unnecessary exposure to ionizing radiation.

Design/Methods: GFAP and UCH-L1 testing was performed using the i-STAT Alinity test run on whole blood from children (aged 0-17) who presented to our hospital as a trauma activation with blunt trauma and who had a HCT and blood draw within 24 hours of injury as part of their standard care. Adult thresholds were applied, and a test was considered positive if either GFAP or UCH-L1 were elevated. Sensitivity, specificity, positive-predictive value (PPV), and negative-predictive value (NPV) were calculated for detection of intra-cranial injury on HCT.

Results: To date, 51 patients (age 0-17 years, median 9.5 IQR [1.1-14.1]) were recruited, 19 of whom had an intracranial injury on HCT. GCS ranged from 13-15 (median 15). Tests were run between 30 min to 11 hours of injury (median 3:36 [1:30-5:25]). For detection of intracranial injury, sensitivity and NPV value were 1.00 (95%CI 0.82-1.00 and 0.79-1.00, respectively). Specificity was 0.50 (0.32-0.68) and PPV 0.54 (0.37-0.71). There were no false negative results. Of the 16 true negatives, 6 (38%) were admitted to the floor and 1 admitted to the ICU for trauma to the eye. No patients required neurosurgical intervention.

Conclusion(s): Our preliminary results suggest that GFAP and UCH-L1 have high sensitivity and NPV for detection of intracranial injury in children using established adult cut-off values. Further analysis of normal values across ages is needed to establish true normal range for children. In our study, 16/51 (31%) of patients could have avoided HCT if decision making was based on the test. Clinical use of GFAP and UCH-L1 may allow for a reduction in the number of HCT scans obtained in children with blunt head trauma.