Improved performance of Elecsys CSF Abeta measurement achieved using the simple, unified routine‐use protocol for CSF collection

Background Cerebrospinal fluid (CSF) biomarkers amyloid‐β1–42 (Abeta42), amyloid‐β1–40 (Abeta40), phospho‐tau (pTau) and total tau (tTau) can support the diagnosis of Alzheimer’s disease (AD); pre‐analytical handling differences are a known source of variability in measured levels of these biomarkers. An industry consortium chaired by the Alzheimer’s Disease Association developed a simplified Routine‐Use CSF sample handling protocol intended for universal adoption in clinical practice. Method CSF samples from patients with normal pressure hydrocephalus were collected per the Routine‐Use protocol for fresh CSF (n=3 aliquots per patient) and two clinical trial protocols (BioFINDER and Roche Trial) for frozen CSF (n=4 aliquots per patient). Abeta42, pTau and tTau concentrations were quantified by commercially available Elecsys® immunoassays; Abeta40 was measured using a research‐use only prototype immunoassay. Routine‐Use samples were measured for each biomarker within 48h of collection, and subsequently frozen and stored (–20°C; ≥1 week) and remeasured. BioFINDER and Roche Trial samples were stored (