Literature Review

Blood test may reveal brain injury



In trauma patients with normal mental status, two blood biomarkers incrementally increase across three injury types, according to a study of more than 700 adult and pediatric patients. Levels of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) are lowest in patients with nonconcussive body trauma, higher in patients with nonconcussive head trauma, and highest in patients with concussion, researchers reported Aug. 26 in BMJ Paediatrics Open.

Linda Papa, MD, an emergency medicine doctor at Orlando Health Orlando Health

Dr. Linda Papa

“GFAP outperformed UCH-L1 in detecting concussion in both children and adults within 4 hours of injury,” reported lead author Linda Papa, MD, and collaborators. Dr. Papa is an emergency medicine doctor at Orlando Health. “UCH-L1 was expressed at much higher levels than GFAP in those with nonconcussive trauma, particularly in children. Elevations of these biomarkers in nonconcussive head trauma suggest possible subconcussive brain injury. GFAP could be potentially useful to detect concussion for up to a week post injury.”

In 2018 the Food and Drug Administration approved the use of these biomarkers to guide CT scan ordering in adults with mild to moderate traumatic brain injury, but investigators have not established their ability to detect concussion in children or adults. Clinicians lack an objective measure to diagnose concussion acutely.

To assess the ability of GFAP and UCH-L1 to detect concussion, Dr. Papa and colleagues conducted a prospective cohort study. The researchers enrolled trauma patients of all ages at three level I trauma centers in the United States. They included patients with and without head trauma who had a Glasgow Coma Scale score of 15 and who presented within 4 hours of injury. Investigators screened for concussion symptoms, obtained biomarker data from 712 trauma patients, and conducted repeated blood sampling in adults.

They grouped patients by those with concussion (n = 371), those with head trauma without overt signs of concussion (n = 149), and those with peripheral trauma without head trauma or concussion (n = 192). The study included 175 children. Injury mechanisms included car crashes, falls, bicycle accidents, and sports injuries.

Patients with concussion had significantly higher GFAP concentrations, compared with patients with body trauma and patients with nonconcussive head trauma. UCH-L1 levels did not significantly differ between patients with concussion and head trauma controls, however.

“Based on these results, the potential utility of GFAP to distinguish concussion from body trauma controls over 7 days postinjury was fair to excellent,” with area under the receiver operating characteristics curves (AUCs) of 0.75-0.89, the researchers said. “UCH-L1’s ability was guarded and variable with AUCs from poor to good depending on timing of samples.” UCH-L1 demonstrated AUCs that ranged from 0.54 to 0.78; earlier samples performed better.

GFAP elevations in head trauma controls “may represent milder forms of concussion that do not elicit typical signs or symptoms associated with concussion,” the authors wrote. “These injuries may be irrelevant, or they may represent important trauma that is just below the level of clinical detection and referred to as subconcussive trauma. ... Biomarkers (such as GFAP and UCH-L1) could provide a more objective measure of injury and potentially identify those at risk for neurocognitive problems.”

The study was supported by the National Institute of Neurological Disorders and Stroke. Dr. Papa is an unpaid scientific consultant for Banyan Biomarkers, which developed kits to measure the biomarkers, and coauthors receive contract research funding from Banyan Biomarkers.

SOURCE: Papa L et al. BMJ Paediatr Open. 2019 Aug 26. doi: 10.1136/bmjpo-2019-000473.

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