Blood Test May Reduce CT Use in Diagnosing TBI

June 4, 2015

CT may be used less often in diagnosing TBI with early measurement of glial fibrillary acidic protein and its breakdown products (GFAP-BDP).

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.”