Comparison between ELISA and SIMOA assay for detection of serum neurofilament light chain in post-anoxic...

Neurofilament light chain (NfL) is a biomarker of neuronal injury that has been studied across various neurological conditions. It has emerged as a reliable and highly sensitive predictor of neurological outcome in post-anoxic encephalopathy following cardiac arrest. The clinical application of serum NfL (sNFL) detection is limited by the high costs and restricted availability of the SIMOA (Single Molecule Array), which is not routinely used and lacks clinical validation.

We measured sNfL levels using both ELISA (Enzyme-Linked Immunosorbent Assay) and SIMOA on the same blood samples (collected at 24 and 72 h after hospital admission) from a cohort of 50 post-cardiac arrest patients (91 samples).

sNfL concentrations, measured using ELISA, were able to predict mortality at hospital discharge with high accuracy (AUC = 0.99). At 72 h, the NfL cut-off corresponding to 100% specificity for mortality was 755.4 pg/mL with ELISA and 529.9 pg/mL with SIMOA (absolute difference: 225.5 pg/mL). The corresponding cut-off for survival at hospital discharge was 170.4 pg/mL with ELISA and 135.6 pg/mL with SIMOA (absolute difference: 34.8 pg/mL).

We found an overall agreement between the two methods of sNFL quantification with a correlation coefficient of 0.98 (95% CI: 0.98-0.99) but a proportional bias for high values. ELISA showed similar results in terms of outcome prediction after cardiac arrest.

Further studies are needed to confirm ELISA sNfL quantification as a promising and accessible alternative for neuro-prognostication of post-anoxic encephalopathy, impacting care and treatment decisions, with sustainable costs for the health system.