NEW YORK (360Dx) – Clinical guidelines err on the side of caution in cases of head injury, sometimes recommending a CT scan for anyone who shows altered alertness. Now, a study of more than 1,900 people suggests a test for two blood-based biomarkers may be useful to rule out traumatic brain injuries, obviating the need for CT scans in many patients.
The study, published yesterday in The Lancet Neurology, describes a multicenter observational trial called ALERT-TBI that was conducted in emergency departments in the US and Europe. The trial compared CT scans of patients to a blood test that measured two biomarkers thought to be released into the bloodstream after TBI.
The blood test evaluated was the Brain Trauma Indicator from Banyan Biomarkers, which measures levels of ubiquitin C-terminal hydrolase-L1 (UCH-L1) and glial fibrillary acidic protein (GFAP) released into the blood within 12 hours of injury. The ALERT-TBI study was funded by Banyan as well as by the US Army Medical Research and Materiel Command.
Banyan's Brain Trauma Indicator was cleared for marketing by the US Food and Drug Administration earlier this year through its de novo process for novel devices. However, the firm noted at the time that it was collaborating with Abbott and BioMérieux to incorporate UCH-L1 and GFAP in point-of-care concussion tests and panels those firms are developing.
In the US, TBI leads to 2.5 million emergency department visits each year, often for milder injuries like concussions, which account for three-quarters of all TBI cases, according to the US Centers for Disease Control and Prevention. To detect injuries, doctors currently rely on CT scans, but these reveal that patients have brain injuries, such as bleeding, in only a fraction of cases.
The blood-based test was compated to the standard of care CT scans. It was positive in about 98 percent of patients whose head CT scan showed a traumatic injury, and had a negative predictive value of more than 99 percent. The authors concluded that the ALERT-TBI study results suggest that patients with mild TBI who have no other indication for a CT scan, such as a neurologic deficit, and who have a negative Brain Trauma Indicator test, can safely avoid a scan.
"Routine use of the new biomarker test in emergency departments could reduce head CT scans by a third in acutely head-injured patients thought to be in need of CT scanning, avoiding unnecessary CT-associated costs and radiation exposure, with a very low false-negative rate," said Jeffrey Bazarian, a professor of emergency medicine at the University of Rochester School of Medicine and coauthor of the study, in a statement.
The ALERT-TBI study did not measure the value of the biomarker test, however, and this proved to be a major sticking point for the authors of a commentary article published with the study in The Lancet Neurology.
"The only clinically relevant question for any new diagnostic test in mild TBI is, does the test add value," for example, by yielding better outcomes or reduced costs, compared to current biomarkers and decision rules, wrote Andrew Maas and Hester Lingsma, professors at Antwerp University Hospital in Belgium and Erasmus University Medical Center in the Netherlands, respectively.
"Our interpretation is that the added value of the test in clinical practice might well be small or even absent, and we strongly encourage the authors to prove us wrong," they wrote, concluding "Scientific knowledge deserves primacy over marketing and regulatory aspects. Although we are strong advocates of early interaction with regulatory authorities, it would appear that in the case of ALERT-TBI, the pursuit of scientific knowledge might have suffered."
However, Robert Welch, corresponding author on The Lancet Neurology study, pointed out in an interview that while applying clinical decision rules may indeed be less costly than diagnostics, they only slightly reduced the number of CT scans performed in a recent comprehensive study, while the ALERT-TBI study showed a 35 percent reduction.
"We will be doing a cost analysis now that we have shown the test has diagnostic capability," he said, adding that this study is already in the early stages. Welch also noted that he and his coauthors followed guidelines for reporting studies of diagnostic tests as described by STARD, or Standards for the Reporting of Diagnostic Accuracy studies.Â