BACKGROUND: Acute intoxication is common in patients evaluated for traumatic brain injury (TBI). However, the effect of elevated blood alcohol levels (BALs) on the diagnostic accuracy of FDA-cleared biomarkers for evaluating traumatic intracranial injury on computed tomography (CT) scan, namely, glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), has not been well studied. METHODS: We investigated the effect of significantly elevated (>
300 mg/dL) and modestly elevated BAL (81-300 mg/dL) at emergency department presentation on the diagnostic accuracy of GFAP and UCH-L1 for predicting a positive CT in patients presenting to 18 U.S. Level I trauma centers within 24 h of TBI as part of the prospective, Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. Plasma GFAP and UCH-L1 were measured using Abbott i-STAT Alinity and ARCHITECT assays. Discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). RESULTS: Of 2320 TRACK-TBI participants studied, 54 (2.3%), 332 (14.3%), 1209 (52.1%), and 725 (31.3%) had significantly elevated BAL, modestly elevated BAL, nonelevated BAL (0-80 mg/dL), and no BAL available, respectively
48.3% of the cohort had a positive brain CT. Those with significantly elevated and modestly elevated BAL were more likely to have positive CT (61.1% and 60.5% vs. 46.9% and 44.0%) and had higher plasma GFAP and UCH-L1 levels than those with nonelevated BAL and no BAL available. The AUC of GFAP and UCH-L1 combined for predicting CT positivity was higher in those with significantly elevated BAL (0.949) than those with modestly elevated BAL (0.858), nonelevated BAL (0.849), and no BAL available (0.883). CONCLUSIONS: Modestly and significantly elevated BAL does not lower the diagnostic accuracy of GFAP and UCH-L1 for predicting traumatic intracranial injury on CT. These biomarkers may be useful in decreasing avoidable brain CT imaging in persons with acute alcohol intoxication.