Concordance of CSF measures of Alzheimer's pathology with amyloid PET status in a preclinical cohort: A comparison of Lumipulse and established immunoassays.

INTRODUCTION: We assessed the concordance of cerebrospinal fluid (CSF) amyloid beta (Aß) and tau measured on the fully automated Lumipulse platform with pre-symptomatic Alzheimer's disease (AD) pathology on amyloid positron emission tomography (PET). METHODS: In 72 individuals from the Insight 46 study, CSF Aß40, Aß42, total tau (t-tau), and phosphorylated tau at site 181 (p-tau181) were measured using Lumipulse, INNOTEST, and Meso Scale Discovery (MSD) assays, and inter-platform Pearson correlations were derived. Logistic regressions and receiver-operating characteristic analysis generated CSF cut-points optimizing concordance with 18F-florbetapir amyloid PET status (n = 63). RESULTS: Measurements of CSF Aß, p-tau181, and their ratios correlated well across platforms (r 0.84-.94, P < .0001); those of t-tau and t-tau/Aß42 correlated moderately (r 0.57-0.79, P < .0001). The best concordance with amyloid PET (100% sensitivity and 94% specificity) was afforded by cut-points of 0.110 for Lumipulse Aß42/Aß40, 0.087 for MSD Aß42/Aß40, and 25.3 for Lumipulse Aß42/p-tau181. DISCUSSION: The Lumipulse platform provides comparable sensitivity and specificity to established CSF immunoassays in identifying pre-symptomatic AD pathology.