BY LIZETTE BORRELI
A high sensitivity blood test accurately determined whether a CT scan was necessary in patients with suspected traumatic brain injury (TBI), according to a large, multicenter observational trial published online on July 24 in The Lancet Neurology.
The diagnostic blood test, known as the Banyan Brain Trauma Indicator, or Banyan BTI, developed by Banyan Biomarkers Inc., correctly identified 99.6 percent of patients who did not have a TBI on the head CT scans. The US Food and Drug Administration (FDA) approved the blood test in February based on early, unpublished results of ALERT-TBI, now available in the current study.
The blood test measures ubiquitin C terminal hydrolase (UCH-L1) and glial fibrillary acidic protein (GFAP) levels—proteins released from the brain into the blood and measured within 12 hours of the initial head injury.
For the study, a team of international researchers measured the biomarker test's ability to predict traumatic intracranial injuries on head CT scan within 12 hours of TBI.
A total of 1959 patients underwent noncontrast head CT scanning and blood sampling within 12 hours of injury conducted at 22 sites; patients were at least 18 years old, and had to show suspected nonpenetrating TBI from external force. A Glasgow Coma Scale (GCS) score of 9 to 15—GCS scores range from 3 [deep coma] to 15 [full consciousness]—was also required.
The researchers found 98 percent of patients with TBI who had a head CT scan had a GCS score of 14 to 15; 6 percent had a traumatic intracranial injury on head CT, and less than 1.0 percent had neurosurgically manageable lesions.
Among those who were CT positive, both GFAP and UCH-L1 concentrations were significantly higher, compared to patients who were CT negative (median GFAP 135.0 vs 22.2 pg/mL (p<.0001). In all patients with TBI, 66 percent had a positive test and 34 percent had a negative test. Overall test sensitivity was 0.976 (95% confidence interval, 0.931 - 0.995), and the negative predictive value was 0.996 (95% confidence interval, 0.987 - 0.999) for acute intracranial injury, the researchers reported.
Notably, the test was 100 percent sensitive with a 100 percent negative predictive value for detecting neurosurgically manageable lesions.
Overall, the study revealed there were ten times as many positive GFAP and UCH-L1 tests as positive CT scans among patients with TBIs. This suggests that "these two proteins might be detecting more subtle degrees of injury not visible on CT scan," the researchers, led by Jeffrey Bazarian, MD, MPH, professor in the department of emergency medicine at the University of Rochester Medical Center in New York, wrote.
The findings warrant further research to compare this biomarker test to more sensitive indicators of traumatic axonal injury, including diffusion tensor imaging and to clinical recovery to develop novel techniques in TBI diagnostics, the researchers concluded.
Limitations presented in the study were a lack of ability to determine clinical outcomes, such as prolonged post-concussive symptoms, cognitive impairment, and decreased functional status; its failure to compare diagnostic accuracy with currently used biomarkers and clinical decision rules for triaging CT scanning; and running a separate test for each of the proteins separately to determine if one might perform as well as the two proteins combined.
For more insights into the blood test approved by the FDA in February, read Neurology Today's report, "In the Clinic-Traumatic Brain Injury: FDA Approves First Blood Test for Brain Bleeds After Mild TBI/Concussion."
The study was funded by Banyan Biomarkers and US Army Medical Research and Materiel Command.
The researchers discosed that Dr. Bazarian received funding from Banyan Biomarkers and research funding from BrainScope Company while the study was conducted. The other authors' disclosures are listed in the full paper.
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Baxarian JJ, Biberthaler P, Welch RD, et al. Serum GFAP and UCH-L1 for prediction of absence of intracranial injuries on head CT (ALERT-TBI): a multicentre observational study. Lancet Neurol 2018; Epub 2018 24 Jul.