Comparing CSF amyloid-beta biomarker ratios for two automated immunoassays, Elecsys and Lumipulse, with amyloid PET...

We evaluated for two novel automated biomarker assays how cerebrospinal fluid (CSF) amyloid beta (Aβ)_{1- 42}-ratios improved the concordance with amyloid positron emission tomography (PET) positivity compared to Aβ_{1- 42} alone.

We selected 288 individuals from the Amsterdam Dementia Cohort across the Alzheimer's disease clinical spectrum when they had both CSF and amyloid PET visual read available, regardless of diagnosis. CSF Aβ_{1- 42}, phosphorylated tau (p-tau), and total tau (t-tau) were measured with Elecsys and Lumipulse assays, and Aβ_1-40 with Lumipulse. CSF cut-points were defined using receiver operating characteristic (ROC) for amyloid PET positivity.

For both Elecsys and Lumipulse the p-tau/Aβ_{1- 42}, Aβ_{1- 42}/Aβ_{1- 40}, and t-tau/Aβ_{1- 42} ratios showed similarly good concordance with amyloid PET (Elecsys: 93,90,90%; Lumipulse: 94,92,90%) and were higher than Aβ_{1- 42} alone (Elecsys 85%; Lumipulse 84%).

Biomarker ratios p-tau/Aβ_{1- 42}, Aβ_{1- 42}/Aβ_{1- 40}, t-tau/Aβ_{1- 42} on two automated platforms show similar optimal concordance with amyloid PET in a memory clinic cohort.