Blood Test Detects Traumatic Brain Injury Reducing Unnecessary Imaging

They evaluated the ability of the blood-based biomarker to predict intracranial injury as compared to the findings on an admission CT and a delayed MRI scan. A total of 215 patients were available for analysis and approximately 73% of patients were male.

Serum samples were collected within 24 hours of injury and were dated and time stamped to compare with time of injury. Blinded sample analysis was performed in a single laboratory (Banyan Biomarkers; Alachua, FL, USA) using a sandwich enzyme-linked immunosorbent assay (ELISA) to GFAP-BDP. The GFAP ELISA utilized a proprietary mouse monoclonal antibody for solid-phase immobilization, and a proprietary polyclonal rabbit antibody for detection.

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.

The authors reported a net benefit for the use of GFAP-BDP above imaging-based screening alone and a net reduction in unnecessary scans by 12% to 30%. Calculation of a cut-off value to maximize accuracy in the mild and moderate injury range specifically yielded a GFAP-BDP level of 0.6 ng/mL, with a sensitivity of 67%, a specificity of 89%, and a Brier score of 0.21. A cut-off value to maximize specificity was calculated at a GFAP-BDP concentration of 1.66 ng/mL, resulting in a sensitivity of 45%, specificity of 99%, and a Brier score of 0.29.

John T. Povlishock, PhD, a professor at Virginia Commonwealth University (Richmond, VA, USA) said, “Importantly, this study significantly expands upon other studies that speak to the usefulness of GFAP and, specifically, serum-derived GFAP-BDP in identifying those traumatically brain injured patients whose clinical course is complicated by intracranial injury, demonstrating that GFAP-BDP offers good predictive ability, significant discrimination of injury severity, and net benefit in reducing the need for unnecessary scans, all of which have significant implications for the brain-injured patient.” The study was published on April 7, 2015, in the Journal of Neurotrauma.

Related Links:
University of Pittsburgh Medical Center 
Banyan Biomarkers 
Virginia Commonwealth University