Glial Fibrillary Acidic Protein and Ubiquitin C-Terminal Hydrolase L1 for Acute Traumatic Intracranial Lesions: The PIONEER Diagnostic Accuracy Study.

OBJECTIVE To determine the diagnostic accuracy of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) for detecting clinically significant acute traumatic intracranial lesions in emergency department patients who undergo brain computed tomography (CT) after blunt trauma. METHODS We conducted a retrospective study of 1,867 patients aged more than or equal to 18 years, who presented with trauma-related complaints, underwent brain CT, and had residual samples collected less than or equal to 24 hours postinjury. We evaluated the diagnostic accuracy of GFAP and UCH-L1 using the Abbott i-STAT TBI Plasma test. Additionally, we assessed diagnostic accuracy within key clinical subgroups to define a proposed implementation cohort and assessed the diagnostic accuracy of the biomarkers within this cohort. RESULTS Among 1,867 patients, 49 (2.6%) had clinically significant traumatic intracranial lesions. Elevated GFAP or UCH-L1 demonstrated 96% sensitivity (95% confidence interval [CI] 86% to 99%), 30% specificity (95% CI 28% to 32%), positive likelihood ratio (LR+) of 1.38 (95% CI 1.29 to 1.47), and negative likelihood ratio (LR-) of 0.13 (95% CI 0.03 to 0.53). Two patients had clinically significant CT lesions without elevated GFAP or UCH-L1. In the proposed implementation cohort of adults aged more than or equal to 18 years without coagulopathy elevated GFAP or UCH-L1 had a sensitivity of 100% (95% CI 86% to 100%), specificity of 33% (95% CI 31% to 36%), LR+ of 1.50 (95% CI 1.44 to 1.56), and LR- of 0.00 (95% CI 0.00 to 0.95). CONCLUSION Plasma GFAP and UCH-L1 in combination, measured ≤24 hours postinjury, demonstrated high sensitivity for clinically significant acute traumatic intracranial lesions. Further research is needed to determine whether deploying these biomarkers in the proposed implementation cohort decreases avoidable brain CT scans.