Doctors can detect evidence of a concussion up to one week after a patient is injured by using a simple blood test, according to a report published online ahead of print March 28 in JAMA Neurology. Researchers tested two blood biomarkers—glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1)—separately and together in patients with mild and moderate traumatic brain injury (TBI) within seven days of the injury. They examined the blood biomarkers with respect to diagnostic precision of TBI, presence of traumatic intracranial lesions detectable by CT, and need for neurosurgical intervention. Linda Papa, MDCM, MSc, and colleagues reported that GFAP performed consistently in detecting mild to moderate TBI, CT lesions, and the need for neurosurgical interventions across seven days. UCH-L1, they said, performed best in the early postinjury period.
Linda Papa, MDCM, MSc
“We have so many diagnostic blood tests for different parts of the body, like the heart, liver and kidneys, but there’s never been a reliable blood test to identify trauma in the brain,” said Dr. Papa, an emergency medicine physician at Orlando Health in Florid and lead author of the study. “We think this particular test could change that.”
Dr. Papa and colleagues designed a prospective cohort study that enrolled adults with trauma seen at a level 1 trauma center from March 1, 2010, to March 5, 2014. All patients underwent screening to determine whether they had experienced mild or moderate TBI, which was defined as blunt head trauma with loss of consciousness, amnesia, or disorientation and a Glasgow Coma Scale score of 9 to 15. Of 3,025 patients assessed, 1,030 met eligibility criteria for enrollment; 446 declined participation. Initial blood samples were obtained in 584 patients enrolled within four hours of injury. Repeated blood sampling was conducted every four hours up to 24 hours postinjury, and then every 12 hours thereafter until 180 hours postinjury.
A total of 1,831 blood samples were drawn from 584 patients (mean age, 40; 62% male) over seven days. Both GFAP and UCH-L1 were detectible within one hour of injury. GFAP peaked at 20 hours postinjury and slowly declined over 72 hours. UCH-L1 rose rapidly and peaked at eight hours postinjury, then declined rapidly over 48 hours.
Over the course of one week, GFAP demonstrated a diagnostic range of areas under the curve for detecting mild to moderate TBI of 0.73 to 0.94, and UCH-L1 demonstrated a diagnostic range of 0.30 to 0.67. For detecting intracranial lesions on CT, the diagnostic ranges of areas under the curve were 0.80 to 0.97 for GFAP and 0.31 to 0.77 for UCH-L1. For distinguishing patients with and without the need for a neurosurgical intervention, the range for GFAP was 0.91 to 100 and the range for UCH-L1 was 0.50 to 0.92.
“In the context of developing a point-of-care test, the early and rapid rise of UCH-L1 could be used to detect TBI immediately at the scene of injury in settings such as in the ambulance, on the playing field, or at the battlefield,” the researchers wrote. “The longer half-life of GFAP makes it a favorable biomarker to use in both the acute and subacute phases of injury because it is able to detect CT lesions for up to seven days after injury. Although its rise is not as rapid as [that of] UCH-L1, it performs well for detecting mild TBI and CT lesions within one hour of injury.”
—Glenn S. Williams