Diagnostic Accuracy of Plasma p-tau217 for Detecting Pathological Cerebrospinal Fluid Changes in Cognitively Unimpaired Subjects Using the Lumipulse Platform

Background Plasma biomarkers of Alzheimer’s disease (AD), especially p-tau217, are promising tools to identify subjects with amyloid deposition in the brain, determined either by cerebrospinal fluid (CSF) or positron emission tomography. However, it is essential to measure them in an accurate and fully automated way in order to apply them in clinical practice. Objectives To evaluate the diagnostic performance of the fully-automated Lumipulse plasma p-tau217 assay in preclinical AD. Design Cross-sectional analyses from a prospective cohort. Setting A population-based study. Participants Volunteers over 55 years without cognitive impairment or contraindications for complementary tests. Measurements Plasma p-tau217 was measured with the fully-automated Lumipulse assay, as well as CSF Aβ40, Aβ42, p-taul81, and t-tau levels. We correlated plasma p-tau217 with CSF Aβ40, Aβ42 and p-tau181, and assessed the differences in plasma p-tau217 according to CSF amyloid status (A−/+), AD status (AD+ being those subjects A+T+ and AD- the rest) and ATN group. We performed ROC curves and measured the areas under the curve (AUC) using CSF amyloid as result, and both p-tau217 and ApoE4 status as predictor. Results We screened 209 cognitively unimpaired volunteers with a mean age 64 years (60–69) and 30.2% of ApoE4 carriers. Plasma p-tau217 correlated significantly with CSF Aβ42/Aβ40 (Rho=−0.51; p-value