Blood Test May Reduce CT Use in Diagnosing TBI

Early measurement of glial fibrillary acidic protein and its breakdown products (GFAP-BDP) can contribute to diagnosis and triage of patients with traumatic brain injury (TBI), reducing the use of CT imaging, according to a study published in the Journal of Neurotrauma.

Researchers from the United States, the Netherlands, Belgium, and the United Kingdom performed a multi-center, prospective, cohort study to evaluate the use of GFAP-BDP in the diagnosis of intracranial injury in patients with a positive clinical screen for head injury.

The researchers analyzed blood GFAP-BDP levels in 215 patients, ranging in age from 16 to 93 (mean age, 42.1±18), who presented to an emergency department within 24 hours of a head injury and had a positive clinical screen for acute TBI. Eight-three percent suffered mild TBI, 4% moderate, and 12% severe. Other findings:

• Approximately 73% of patients were male

• 70% of patients had a documented loss of consciousness (LOC)

• 38% of patients had documented post-traumatic amnesia (PTA)

• Median Injury Severity Score (ISS) was 10 (IQR, 17), with 36% suffering significant polytrauma (ISS, ≥16)

The GFAP-BDP proved to have good predictive ability (AUC=0.87) and significant discrimination of injury severity, the researchers found. The use of GFAP-BDP yielded a net benefit above clinical screening alone and a net reduction in unnecessary scans by 12% to 30%: “GFAP-BDP level was the most accurate predictor of the presence or absence of intracranial injury detected by radiographic imaging (accuracy, 81%), as compared with accepted clinical predictors of intracranial injury (age, 65%; GCS, 62%; LOC and/or PTA, 54%; pupillary status, 52%).”

The researchers found that the accuracy of GFAP-BDP for injury prediction was superior to the ACEP/CDC recommended criteria for neuroimaging in TBI (81% versus 65%, respectively). “Used in conjunction with other clinical information, rapid measurement of GFAP-BDP is useful in establishing or excluding the diagnosis of radiographically apparent intracranial injury throughout the spectrum of TBI. As an adjunct to current screening practices, GFAP-BDP may help avoid unnecessary CT scans without sacrificing sensitivity.”