%V 14 %P 1470-1481 %D 2018 %O Copyright © 2018 The Authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). %K Amyloid PET concordance, Amyloid-β (1–42), Biomarker validation, CSF biomarkers, Clinical progression, Cutoffs, Phosphorylated tau (pTau), Total tau (tTau) %X INTRODUCTION: We studied whether fully automated Elecsys cerebrospinal fluid (CSF) immunoassay results were concordant with positron emission tomography (PET) and predicted clinical progression, even with cutoffs established in an independent cohort. METHODS: Cutoffs for Elecsys amyloid-β1-42 (Aβ), total tau/Aβ(1-42), and phosphorylated tau/Aβ(1-42) were defined against [18F]flutemetamol PET in Swedish BioFINDER (n = 277) and validated against [18F]florbetapir PET in Alzheimer's Disease Neuroimaging Initiative (n = 646). Clinical progression in patients with mild cognitive impairment (n = 619) was studied. RESULTS: CSF total tau/Aβ(1-42) and phosphorylated tau/Aβ(1-42) ratios were highly concordant with PET classification in BioFINDER (overall percent agreement: 90%; area under the curve: 94%). The CSF biomarker statuses established by predefined cutoffs were highly concordant with PET classification in Alzheimer's Disease Neuroimaging Initiative (overall percent agreement: 89%-90%; area under the curves: 96%) and predicted greater 2-year clinical decline in patients with mild cognitive impairment. Strikingly, tau/Aβ ratios were as accurate as semiquantitative PET image assessment in predicting visual read-based outcomes. DISCUSSION: Elecsys CSF biomarker assays may provide reliable alternatives to PET in Alzheimer's disease diagnosis. %A O Hansson %A J Seibyl %A E Stomrud %A H Zetterberg %A JQ Trojanowski %A T Bittner %A V Lifke %A V Corradini %A U Eichenlaub %A R Batrla %A K Buck %A K Zink %A C Rabe %A K Blennow %A LM Shaw %A . Swedish BioFINDER study group %A . Alzheimer's Disease Neuroimaging Initiative %T CSF biomarkers of Alzheimer's disease concord with amyloid-β PET and predict clinical progression: A study of fully automated immunoassays in BioFINDER and ADNI cohorts %J Alzheimer's & Dementia %C United States %N 11 %L discovery10051921