In the results of a prospective observational trial published in Lancet Neurology, researchers found that a combination test consisting of ubiquitin C-terminal hydrolase-L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) features a high sensitivity and negative predictive value for detecting traumatic intracranial injuries on head computed tomography (CT) scan following a traumatic brain injury (TBI).
Adult patients with suspected and non-penetrating TBI and a Glasgow Coma Scale score of 9 to 15 were enrolled in the study (n=1959). All patients had received a head CT scan during emergency care and had blood collected within 12 hours of a TBI. Cut-off values for serum UCH-L1 and GFAP were 327 pg/mL and 22 pg/mL, respectively. The investigators compared head CT results with combination results of the UCH-L1 and GFAP in regard to sensitivity and negative predictive value for detecting traumatic intracranial injury.
Intracranial injuries were detected on head CT in 6% (n=125) of patients, whereas neurosurgically manageable injuries were found in <1% of patients. A majority of patients (66%) had positive UCH-L1 and GFAP test results, whereas a smaller percentage of participants (34%) had a negative result. In <1% of patients, results on a CT scan were positive when the combination test results were negative. The combination test of UCH-L1 and GFAP had a sensitivity of 0.976 (95% CI, 0.931-0.995) and a negative predictive value of 0.996 (95% CI, 0.987-0.999) for detecting intracranial injury.
A limitation of the combined UCH-L1 and GFAP test in the analysis was the lack of assessment of whether the test was predictive of other relevant clinical outcomes in this patient population.
The investigators concluded that their findings “support the potential clinical role of this biomarker test for ruling out the need for a head CT scan among patients with TBI presenting at emergency departments in whom a head CT is felt to be clinically indicated.”
Bazarian 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 [published online July 24, 2018]. Lancet Neurol. doi:10.1016/S1474-4422(18)30231-X