Comparison of SIMOA and VEUS technologies for serum neurofilament light chain measurement in multiple sclerosis

Introduction: The gold standard for serum neurofilament light chain (sNfL) determination is the single molecule array (SIMOA), the use of which is limited by availability and cost. The VEUS method is a fully automated, userfriendly diagnostic system requiring no sample preparation, with high reported sensitivity, multiplexing capability, and rapid diagnostics. The aim of this study was to compare the SIMOA and VEUS methods for determining sNfL levels in patients with multiple sclerosis (MS). Methodology: A single-centre cross-sectional study was conducted at the MS Centre of University Hospital Ostrava. Patients were enrolled in the study from January 18 to January 31, 2024. Inclusion criteria were: 1) diagnosis of MS according to the revised 2017 McDonald criteria, 2) age >= 18 years, and 3) signed informed consent. The NF-light V2 diagnostic kit (SIMOA, Quanterix) and the Singleplex Neurology assay kit (VEUDx, EZDiatech) were used to determine sNfL concentrations. The two methods were compared by use of Spearman correlation, Passing-Bablok regression, and Bland-Altman analysis. Results: A total of 49 patients were included in the study, of whom 39 (79.6 %) were female. The median sNfL concentration was 7.73 (IQR 5.80-9.93) ng/L determined by SIMOA and 1.31 (IQR 1.18-1.65) ng/L by VEUS. We did not find a correlation between SIMOA and VEUS (rs = 0.025, p = 0.866). Passing-Bablok regression demonstrated a systematic and proportional difference between the two methods. A significant disagreement between them was also confirmed by the Bland-Altman plots. On average, sNfL values measured by SIMOA were 3.56 ng/L (95 % CI 0.78 to 6.34) higher than those measured by VEUS. Conclusion: Our investigation uncovered noteworthy disparities between the SIMOA and VEUS techniques in determining sNfL levels. Specifically, the VEUS technique systematically produces lower estimates of sNFL levels. This substantial variance emphasizes the importance of carefully evaluating assay methods when quantifying sNfL.