Study validates FDA-approved blood test for traumatic brain injury
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Recent findings published in JAMA Network Open validate a blood test that uses biomarkers to determine the severity of a traumatic brain injury and whether a CT scan is warranted.
The blood test (Brain Trauma Indicator; Banyan Biomarkers) was approved by the FDA in 2018 for use in conjunction with clinical decision-making.
“We have very good clinical decision rules but the addition of a blood test as an objective measure of injury has an interesting appeal to it,” Linda Papa, MD, MSc, CCFP, FRCP(C), FACEP, the director of academic clinical research at Orlando Health, told Healio. “Adding the biomarker to what we are doing clinically could actually improve our management.”
For the retrospective cohort study, Papa and colleagues enrolled 377 adults with suspected mild to moderate traumatic brain injury (MTBI) who presented within 4 hours of an injury to a level 1 trauma center from March 16, 2010, to March 5, 2014. The researchers compared the diagnostic performance of serum glial fibrillary acidic protein (GFAP) and neuronal ubiquitin C-terminal hydrolase (UCH-L1) biomarkers with validated clinical decision rules for detecting intracranial lesions. The clinical decision rules included the Canadian CT Head Rule (CCHR), New Orleans Criteria (NOC) and National Emergency X-Radiography Utilization Study II (NEXUS II) criteria. Emergency physicians used the biomarkers and clinical decision rules to evaluate patients before CT scans.
The range of quantification for the GFAP assay was 30 pg/mL to 50,000 pg/mL, with a limit of detection of 8 pg/mL. The range of quantification for the UCH-L1 assay was 100 pg/mL to 9,000 pg/mL, with a limit of detection of 45 pg/mL.
Overall, 93% of patients underwent a CT scan and were included in the final analysis. The patients’ mean age was 40 years and 66% were men. Among these patients, 7% had positive CT scan results.
Clinical decision-making
Papa and colleague reported that the CCHR performed with a sensitivity of 100% (95% CI, 82-100), a specificity of 33% (95% CI, 28-39) and a negative predictive value (NPV) of 100% (95% CI, 96-100). For the NOC test, they reported a sensitivity of 100% (95% CI, 82-100), a specificity of 16% (95% CI, 12-20) and an NPV of 100% (95% CI, 91-100). For NEXUS II, the sensitivity was 83% (95% CI, 60-94), the specificity was 52% (95% CI, 47-58) and the NPV was 98% (95% CI, 94-99).
Biomarker blood testing
Comparatively, for the combined GFAP and UCH-L1 levels with cutoffs at 67 pg/mL and 189 pg/mL, respectively, Papa and colleagues reported a sensitivity of 100% (95% CI, 82-100), a specificity of 25% (95% CI, 20-30) and an NPV of 100%. Moreover, with cutoffs at 30 pg/mL and 327 pg/mL, respectively, sensitivity was 91% (95% CI, 70-98), specificity was 20% (95% CI, 16-24) and the NPV was 97%.
Overall, the CCHR test had the highest specificity, according to the researchers. However, they said a combination of the GFAP biomarker and the CCHR test produced the greatest diagnostic performance.
The study is “among the first to evaluate validated clinical decision rules, completed in real time by ED physicians during their clinical evaluations, against newly FDA-approved serum biomarkers GFAP and UCH-L1 in patients with suspected MTBI to detect intracranial lesions on CT scans,” Papa and colleagues wrote.
About 10% of patients with MTBI will have a lesion on their CT, according to Papa
“We want to make sure that our test is very sensitive,” she said. “On the other hand, we also want to be judicious in our use of CT scans. So if we could use the decision rule together with the blood test to reduce the number of scans in patients who don’t need one, then that would definitely be an important accomplishment.”