Clinical utility of concussion injury biomarkers

Cases of traumatic brain injury (TBI) have been steadily rising over the past decade with most common causes of injury observed among participants in contact sports, combat military personnel, and unintentional falls occurring in children and the elderly. These events can range from mild-to-severe injury in the affected individual. Brain imaging using computed tomography (CT) scan is the current gold standard for TBI testing and diagnosis. Mild TBI (mTBI), or concussion injury, is often the most difficult of these to detect because injury to the head region may not be observed on CT scan. Furthermore, CT scanners are not readily available outside of medical institutions. Functional scoring methods, like SCAT5 and Glasgow Coma Scale, may provide the clinician with some evidence of TBI at off-site locations (e.g., on the sports field or in combat zones). Biomarker testing for evidence of TBI has gained popularity as another means towards achieving a reliable diagnosis. A goal of this presentation is to describe TBI, summarize serum biomarkers tests that are used in both clinical and research settings, and suggest alternative means of test interpretation. Concussion biomarkers have shown good promise for ruling out injury (high negative predictive value), while positive test results are often equivocal. The classical way to interpret a biomarker test result is by comparing it to a population-based reference interval established in healthy individuals; the so-called “normal range”.  A potential remedy to improve positive diagnoses is to establish an individual’s own baseline concentration, then compare it with that person’s biomarker concentration after suspected TBI. Serial sampling is used to describe the comparison of two consecutive test results from separate blood draws. Establishing normal biological variation of the biomarker, along with statistical calculation of a “reference change value”, offers an alternative diagnostic strategy for interpreting serial sampling results.

Learning Objectives:

1. Identify current diagnostic tools for assessment of acute concussion/traumatic brain injury (TBI)

2. Describe clinical utility of serum biomarker proteins for detecting concussion injury in human subjects

3. Discuss serial sampling strategy, and reference change value (RCV), to identify a significant change in biomarker test results