Emergency department physicians may soon be turning to a blood test, rather than a CT scan, to diagnose patients with suspected traumatic brain injury (TBI) after researchers discovered an increased blood level of a certain protein in such patients, according to a preliminary study published online in the Annals of Emergency Medicine.
Patients with traumatic brain injuries were shown to have significantly higher levels of glial fibrillary acidic protein (GFAP) than patients without such injuries, marking a promising step in the development of a blood test that could reduce the number of CT scans administered to the 1.4 million people treated annually for traumatic brain injury in U.S. emergency departments.
"This test has the potential for determining injury severity soon after injury, helping emergency physicians make decisions about performing CT scans, seeking neurological consultations and transferring patients to other facilities," Linda Papa, MDCM, MSc, of the department of emergency medicine at Orlando Regional Medical Center in Orlando, Fla., said in a statement. "We can perform blood tests now for heart attack, and hope to be able to do the same for traumatic brain injury.”
The researchers performed a prospective cohort study of 307 adult patients, 108 of whom were patients with traumatic brain injury and 199 of whom were control subjects who were either uninjured or presented with injuries other than traumatic brain injury. Patients with head trauma had Glasgow Coma Scale (GCS) scores between 9 and 15, with symptoms such as loss of consciousness, amnesia or disorientation.
Blood samples were obtained within four hours of injury.
Significant differences in the levels of GFAP were detected between patients with traumatic brain injuries and control patients. Receiver operating characteristic curves demonstrated early GFAP levels could distinguish patients with traumatic brain injury from controls with an area under the curve of 0.90, while the area under the curve for discriminating patients with CT lesions from those without was 0.79.
“GFAP [breakdown product] is detectable in serum within an hour of injury and is associated with measures of injury severity, including the GCS score, CT lesions and neurosurgical intervention,” wrote the authors.
According to the study’s background information, GFAP breakdown products are released from injured glia cells and likely the result of calpain overactivation following traumatic brain injury.
Papa said the GFAP blood test has greater specificity than other blood tests studied for their predictive value in traumatic brain injury, but said it won’t totally replace imaging.
“It is not a substitute for all CT scans, but it could possibly rule out patients who do not need them, as well as ensure that patients at risk get CT scans they need," said Papa.
The researchers said further study is necessary before recommending clinical application of a GFAP blood test.