Blood-Based Biomarkers and Traumatic Intracranial Hypertension: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study

BACKGROUND AND OBJECTIVES: The role of blood-based biomarkers in guiding the acute management of patients with established traumatic brain injury is unclear. We sought to determine whether concentrations of glial fibrillary acid protein (GFAP) or ubiquitin C-terminal hydrolase L1 (UCH-L1) on hospital day 1 are associated with intracranial pressure (ICP) and therapeutic intensity level (TIL). METHODS: We conducted a retrospective cohort study using the Transforming Research and Clinical Knowledge in Traumatic Brain Injury data set, including patients age 17 years and older with traumatic brain injury and invasive ICP monitoring, excluding those undergoing decompressive craniectomy on admission. Patients were stratified into biomarker quartiles, and the relationships with ICP and TIL were analyzed descriptively. Multivariable linear regressions were performed to test the hypothesis that GFAP and UCH-L1 concentrations were independently associated with ICP and TIL after adjusting for a priori defined covariates. RESULTS: Two hundred twenty-nine patients with a median age of 39 years (IQR 26-56) were included. Geometric mean concentrations for GFAP and UCH-L1 were 4423 and 989 pg/mL, respectively. Patients in the lowest GFAP quartile had a median of 7.3% of ICP readings >22 mm Hg vs 23.2% in the highest quartile ( P < .001); secondary decompressive craniectomy was performed in 16% of the lowest quartile, compared with 39% of the highest quartile ( P = .008). After adjusting for covariates, GFAP was significantly associated with ICP burden (B = 8.05, P = .014) and median TIL over 5 days (B = 1.65, P = .009). No significant relationship was seen for UCH-L1. CONCLUSION: Day 1 blood concentration of GFAP is associated with elevated ICP and may be a useful adjunct when risk-stratifying patients for intracranial hypertension.