Second-generation Elecsys cerebrospinal fluid immunoassays aid diagnosis of early Alzheimer’s disease
Kaj Blennow, Erik Stomrud, Henrik Zetterberg, Niels Borlinghaus, Veronika Corradini, Ekaterina Manuilova, Laura S. M. Müller, Frances‐Catherine Quevenco, Sandra Rutz, Oskar Hansson
Abstract
OBJECTIVES: CSF immunoassays (Roche Diagnostics International Ltd), and adjusted existing cut-offs, to evaluate their potential utility in clinical routine. METHODS: Analytical performance was assessed using CSF samples measured with Elecsys CSF Gen II immunoassays on cobas e analyzers. Aβ42 Gen I/Gen II immunoassay method comparisons were performed (Passing-Bablok regression). Cut-off values were adjusted using estimated bias in biomarker levels between BioFINDER protocol aliquots/Gen I immunoassays and Gen II protocol aliquots/immunoassays. Distribution of Gen II immunoassay values was evaluated in AD, mild cognitive impairment (MCI), and cognitively normal cohorts; percentage observations outside the measuring range were derived. RESULTS: The Gen II immunoassays demonstrated good analytical performance, including repeatability, intermediate precision, lot-to-lot agreement (Pearson's r: ≥0.999), and platform agreement (Pearson's r: ≥0.995). Aβ42 Gen I/Gen II immunoassay measurements were strongly correlated (Pearson's r: 0.985-0.999). Aβ42 Gen II immunoassay cut-offs were adjusted to 1,030 and 800 ng/L, and pTau181/Aβ42 ratio cut-offs to 0.023 and 0.029, for Gen II and I protocols, respectively. No observations were below the lower limit of the measuring range; above the upper limit, there were none from the AD cohort, and 2.6 and 6.8% from the MCI and cognitively normal cohorts, respectively. CONCLUSIONS: Our findings suggest that the Gen II immunoassays have potential utility in clinical routine to aid diagnosis of AD.