A Technical Assessment of a Commercial GFAP Lateral Flow Assay to Establish Proof-of-Concept for Use in Traumatic Brain Injury

Glial fibrillary acidic protein (GFAP) is an emerging biomarker for the detection of acute intracranial pathology following acute brain injuries such as traumatic brain injury (TBI), stroke, and hypoxic-ischaemic encephalopathy. We undertake a proof-of-concept technical assessment of a commercial lateral flow test (LFT) for the detection of GFAP [the Upfront DX LVOne GFAP lateral flow assay (LFA)], against GFAP concentrations measured using a gold-standard assay [Single Molecule Arrays (Simoa®)-based Human Neurology 4-Plex B assay] in a TBI population. The ability of the LVOne GFAP LFA for identification of samples with GFAP concentrations above the manufacturer's reported lower limit of detection (≥ 0.2 ng/ml) was assessed, with further assessment of the association between the LVOne and a gold-standard assay made using Spearman's rank correlation coefficient and linear-mixed-effects modelling. Of the 50 samples, 39 had serum GFAP concentrations exceeding the reported lower limit of detection, with the LVOne GFAP LFA having a 95% (95% CI: 83%, 99%) sensitivity and a 64% (95% CI: 31%, 89%) specificity for detecting a serum GFAP concentrations over this lower limit. There was a significant positive correlation (Rho = 0.94, p < 0.001) between the Quanterix Simoa® GFAP level and the LVOne semiquantitative score, with a significant positive association seen using a linear-mixed-effects model (p < 0.001). In conclusion, the Upfront DX LVOne GFAP LFA is sensitive for the detection of elevated serum GFAP levels, and as such, may be a useful adjunct to the care of patients with acute brain injuries in the pre-hospital setting.