Clinical Evaluation of the TBI Assay in a Representative Emergency Department Cohort

Each year, millions of adults present to emergency departments (EDs) with suspected traumatic brain injury (TBI). While more than 80% undergo computed tomography (CT) imaging, the current gold standard for diagnosis, fewer than 10% are found to have acute intracranial abnormalities requiring immediate clinical intervention. This overuse of CT imaging increases costs, length of stay (LOS), and ED crowding. Immunoassays utilizing blood-based biomarkers associated with TBI have shown promise in identifying patients presenting with suspected mild traumatic brain injury (mTBI) who are at low risk for intracranial injury, potentially reducing unnecessary CT scans and ED LOS. The Abbott TBI assay may offer a scalable diagnostic solution; however, real-world performance data remain limited.

Remnant blood specimens were collected from ED patients being evaluated for mTBI with noncontrast CT imaging. These samples were analyzed using the Abbott TBI immunoassay on the Alinity i system, and patient charts were reviewed by 3 independent ED physicians. Analytical and clinical performance of the assay were evaluated.

The TBI immunoassay demonstrated a sensitivity (95% CI) of 100.0% (67.6, 100.0) and specificity of 32.6% (23.7, 42.9) overall, with a 100% negative predictive value and 12% (10, 13) positive predictive value. Stratification by age showed a higher specificity of 47.2% (34.3, 60.3) in patients <65 years compared to 11.0% (4.4, 25.3) for patients ≥65 years.

The TBI assay on the Alinity i platform demonstrated excellent sensitivity but showed limited specificity, particularly in patients >65 years. Our findings support the safe use of the TBI assay as a rule-out tool in the ED.