Biomarker-Based Blood Test Does Not Completely Replace CT Scan for Diagnosis of Elderly Concussion Patients

Detection of intracranial injuries relies on head CT, which is an overused and resource intensive method. Blood-based brain biomarkers hold the potential to predict absence of intracranial injury and thus reduce unnecessary head CT scanning. The [U.S.] Food and Drug Administration has approved use of a blood test that identifies head injury patients who have brain tissue damage that needs to be assessed via CT scan. However, the performance of this test, which determines levels of the proteins serum glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal esterase L1 (UCH-L1) has not been characterized in elderly patients.

In this regard, investigators at the University of Maryland School of Medicine (Baltimore, USA) sought to characterize any difference in the predictive performance of the GFAP/UCH-L1 biomarkers-based test between younger patients, (less than 65 years old) and older patients (more than 65 years old).

For this work, the investigators retrospectively analyzed data from the Prospective Clinical Evaluation of Biomarkers of Traumatic Brain Injury (ALERT-TBI) study. In this study, 1,959 adult patients with a concussion underwent both a CT scan and blood test for brain tissue damage within 12 hours of their injury. Elderly mild TBI patients constituted 25.7% of the patient cohort (504/1959).

Results revealed that the GFAP/UCH-L1 blood test predicted which elderly concussion patients did not have brain tissue damage and did not need a CT scan with 100% accuracy. However, the test did not accurately identify elderly patients who had suffered brain tissue damage, suggesting that the test should only be used as a triage tool, not as a replacement for CT scans.

“This post-hoc analysis of the ALERT-TBI study further validates the utility of the [mild traumatic brain injury] serum assay as a rule-out test across the spectrum of adult ages, based on equivalent sensitivity and negative predictive value,” said senior author Dr. Robert H. Christenson, professor of pathology and medical and research technology at the University of Maryland School of Medicine. “However, the identified differences in specificity and serum GFAP/UCH-L1 values in elderly [traumatic brain injury] patients limits use as a rule-in test, and highlights age-specific characteristics that must be considered in the use of the predictive markers in elderly [mild traumatic brain injury] patients.”

The study was published in the December 30, 2019, online edition of The Journal of Applied Laboratory Medicine.

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University of Maryland School of Medicine