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The FDA has approved for marketing the first blood test that could help determine whether an adult has a concussion (i.e., mild traumatic brain injury [mTBI]). The Banyan Brain Trauma Indicator measures the proteins UCH-L1 and GFAP in a patient's blood within 12 hours of head injury. Levels of these proteins can help indicate whether a patient has a low probability of intracranial lesions and thus does not need a computed tomography (CT) scan. Test results can take 3 to 4 hours.
In a study of nearly 2000 blood samples of adults with suspected mTBI, the Brain Trauma Indicator was 97.5% accurate in predicting intracranial lesions on CT and 99.6% accurate in ruling out lesions.
— Adapted from a Physician's First Watch article published on February 15, 2018
FDA authorizes marketing of first blood test to aid in the evaluation of concussion in adults [press release]. Rockville, MD: U.S. Food and Drug Administration; February 14, 2018. (https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm596531.htm)
Comment
According to the FDA news release, the test could help to avert CT scans in a third of patients with suspected mTBI. Although avoidance of unnecessary imaging is admirable, this is not a test for mTBI but rather one that correlates with positive findings on CT scan after an mTBI. In addition, obtaining test results takes several hours, and the cost is uncertain.
The vast majority of mTBIs have normal imaging results. The importance of acute CT imaging is to detect the presence of a brain hemorrhage that requires surgical intervention, not to diagnose an mTBI. Guidelines from the American College of Emergency Physicians suggest immediate CT scans for specific high-risk groups (Ann Emerg Med 2008; 52:714). It is difficult to imagine that clinicians would delay CT scans until these results come back in high-risk individuals. It is not clear how often individuals in this study required surgery. Most likely, very few individuals who are clinically stable will have CT results requiring immediate neurosurgical intervention. A careful evaluation that includes a cognitive, neurologic, visual, vestibular, and musculoskeletal examination remains the most important (and least expensive) assessment.