Blood Biomarkers Can Predict Outcome of Traumatic Brain Injuries

The test measures the concentration in the blood of the biomarkers glial fibrillary acidic protein (GFAP), which originates in glial cells and ubiquitin C-terminal hydrolase L1 (UCH-L1), which originates in neurons. These biomarkers are already in clinical use for decision making regarding whether brain CT should be performed after traumatic brain injury.

Investigators at the University of California, San Francisco (USA) and their colleagues conducted a study to determine whether levels of these biomarkers measured on the day of injury could predict the likely outcome of the trauma to the brain.

For this study, the investigators used an Abbott (Princeton, NJ, USA) i-STAT Alinity portable blood analyzer with the ARCHITECT assay series to analyze the day-of-injury blood tests of 1,696 patients with TBI. The results of these blood tests were compared at patients’ six-month assessments, using the Glasgow Outcome Scale Extended, which grades outcomes and quantifies levels of disability following TBI. These outcomes range from death to complete recovery with resumption of normal life but minor deficits in some cases.

The study included participants in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) observational cohort study aged 17-90 years who had day-of-injury plasma samples for measurement of GFAP and UCH-L1 and completed six-month assessments for outcome due to traumatic brain injury with the Glasgow Outcome Scale Extended. All patients underwent head CT at evaluation, had adequate visual acuity and hearing prior to the injury, and were fluent in either English or Spanish.

Results revealed that the day-of-injury blood tests demonstrated a high probability of predicting death within six months following the trauma, 87% for GFAP and 89% for UCH-L1; and a high probability of predicting severe disability at the same time point, 86% for both GFAP and UCH-L1. However, they were significantly less accurate in predicting incomplete recovery versus complete recovery: 62% and 61%, respectively.

Clinically, at six months following injury, 7% of the patients had died, 14% had an “unfavorable outcome,” with injuries ranging from vegetative state to severe disability requiring daily support. The remaining 67% had “incomplete recovery” ranging from moderate disabilities requiring assistance outside of the home to minor disabling neurological or psychological deficits.

Senior author Dr. Geoffrey Manley, professor of neurosurgery at the University of California, San Francisco, said, “These blood tests are both diagnostic and prognostic, as well as easy to administer, swift, and inexpensive. We believe this tool may encourage clinicians to be more aggressive in their decisions to begin or continue life-saving treatment. Modern trauma care can result in good outcomes in what we had once believed were non-survivable injuries.”

The study was published in the August 10, 2022, online edition of the journal The Lancet Neurology.

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