- Between 2000 and 2023 TBI affected over 499,852 service members worldwide, with 82.2% of those injuries being classified as mild (mTBI), also known as concussion.1 Common sequelae after mTBI include: headache, visual impairment, Post-Traumatic Stress Disorder (PTSD), depression and cognitive disorders; individuals with a mTBI are at increased risk of posttraumatic stress.2-4 Secondary to these effects, only 70% of individuals diagnosed with mTBI return to full duty.5
- Individuals with mTBI typically have a normal (or negative) head CT. The purpose of head CT in an individual with suspected mTBI is to rule out a more severe injury requiring a higher level of care. For example, intracranial hemorrhage requires inpatient observation and, if severe, neurosurgical intervention. In civilian settings, approximately 6-8% of individuals with suspected mTBI at initial evaluation have evidence of intracranial hemorrhage and 1-2% require neurosurgical intervention.6,7
- CT scanners are typically available in theater at Role 3 facilities and select enhanced Role 2 facilities. The decision to transport a casualty from Role 1 /2 to Role 3 for a head CT can have significant implications for the safety of the flight crew and mission operations. Medical decision making should include an assessment of operational risk.
- An evaluation of the DoD Trauma Registry (DoDTR) suggests 68% of casualties identified as having mTBI were evacuated to the Role 3 for a head CT and 41% to Role 4, with approximately 78% of those Service Members being returned to duty.8 However, it is important to recognize the DoDTR only contains a subset of more severely injured Service Members with a mTBI in theater. Nonetheless, the data suggests that many evacuations for head CT may be avoided.
- The Military Acute Concussion Evaluation 2 (MACE2) provides guidance in the initial evaluation and management of individuals with Glasgow Coma Scale (GCS) score 13-15 in the deployed setting. It includes an assessment of “red flags” to determine the need for head CT and evacuation. The biomarker assay is not intended to replace the MACE2. In addition, the New Orleans Criteria and the Canadian Head CT rule also aid in identifying individuals most likely to benefit from head CT. None of these rules have been validated in the deployed setting.9,10
- Glial Fibrillary Acidic Protein (GFAP) and Ubiquitin Carboxyl-terminal Hydrolase L1 (UCH-L1) are contained within cells in the central nervous system and released upon neuronal damage. Higher levels indicate worsening neuronal injury.
- In March 2024, the U.S. Food and Drug Administration (FDA) approved a whole blood biomarker test for TBI, the i-STAT TBI WB Cartridge with the i-STAT Alinity System. This semi-quantitative assay detects levels of GFAP and UCH-L1 in venous whole blood. A result of “not elevated” on this test has a Negative Predictive Value approaching 100% for determining the absence of acute traumatic intracranial lesions on head CT imaging. (See Appendix C Figure 1 for further information.) This assay is also known as the Analyzer, Traumatic Brain Injury (ATBI) System.
- Key logistical requirements include on-site refrigerated and frozen storage for cartridges and calibration fluids, respectively. Ongoing product development efforts are focused on assessing whether the test cartridges can be stored frozen; simplifying storage requirements and potentially supporting future shelf-life extension activities.

NOTE: Related clinical practice guidelines (CPGs): VA/DoD Clinical practice Guideline for Management of Concussion-Mild Traumatic Brain Injury, JTS Traumatic Brain Injury Management and Basic Neurosurgery in the Deployed Environment CPGs