- Design
- Single-centre prospective diagnostic validation study
- Population
- 104 adults with suspected mild TBI undergoing head CT
- Primary outcome
- Accuracy for intracranial injury on CT
- Effect
- Sensitivity 0.91 (0.59-1.00); specificity 0.22 (0.14-0.31); NPV 0.95
A validation study in Annals of Emergency Medicine, published on 27 October 2026, tested an FDA-cleared plasma test combining GFAP and UCH-L1 in 104 adults with suspected mild traumatic brain injury undergoing head CT at one US trauma centre, with blood drawn within 12 hours.
Eleven had intracranial injury. The test identified 10 of them (sensitivity 0.91, 95% CI 0.59 to 1.00) with a negative predictive value of 0.95, but specificity was only 0.22, so 83 of the 104 results were raised. False positives were older, median age 72. Results were available about two hours before CT reports (1.1 against 3.3 hours). Pooled earlier data gave sensitivity 0.97 and specificity 0.28.
The test can support a decision not to scan in lower-risk patients, but with most older adults testing positive it will not reduce CT use much where falls in the elderly dominate. It does not replace a clinical decision rule, and the authors call for multicentre work on its effect on length of stay and cost.
- Consider the GFAP/UCH-L1 test as an aid to rule out intracranial injury in mild head injury within 12 hours, alongside a decision rule.
- Expect raised results in most older adults; a raised level alone is not an indication of injury.
- Keep anticoagulated and high-risk patients on the CT pathway regardless of the result.
- Audit CT use and missed injuries if you introduce it.
Why it matters
A fast blood test could shorten waits for low-risk patients, but its low specificity limits how many scans it saves.
Don't overread it
A single-centre study with 11 injuries; the sensitivity estimate is imprecise.
The statistics, in plain English
With only 11 positive CTs, the 95% interval for sensitivity runs from 0.59 to 1.00. Specificity of 0.22 means about four in five people without injury still had a raised result, so a positive test means little on its own.
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