P‐tau/Aβ42 and Aβ42/40 ratios in CSF are equally predictive of amyloid PET status
Michelle R. Campbell, Susan Ashrafzadeh‐Kian, Ronald C. Petersen, Michelle M. Mielke, Jeremy A. Syrjanen, Argonde C. van Harten, Val J. Lowe, Clifford R. Jack, Joshua A. Bornhorst, Alicia Algeciras‐Schimnich
Abstract
INTRODUCTION: Measurement of amyloid beta (Aβ40 and Aβ42) and tau (phosphorylated tau [p-tau] and total tau [t-tau]) in cerebrospinal fluid (CSF) can be utilized to differentiate clinical and preclinical Alzheimer's disease dementia (AD) from other neurodegenerative processes. METHODS: CSF biomarkers were measured in 150 participants from the Mayo Clinic Study of Aging and the Alzheimer's Disease Research Center. P-tau/Aβ42 (Roche Elecsys, Fujirebio LUMIPULSE) and Aβ42/40 (Fujirebio LUMIPULSE) ratios were compared to one another and to amyloid positron emission tomography (PET) classification. RESULTS: Strong correlation was observed between LUMIPULSE p-tau/Aβ42 and Aβ42/40, as well as Elecsys and LUMIPULSE p-tau/Aβ42 and Aβ42/40 (Spearman's ρ = -0.827, -0.858, and 0.960, respectively). Concordance between LUMIPULSE p-tau/Aβ42 and Aβ42/40 was 96% and between Elecsys p-tau/Aβ42 and both LUMIPULSE ratios was 97%. All ratios had > 94% overall, positive, and negative percent agreement with amyloid PET classification. DISCUSSION: These data suggest that p-tau/Aβ42 and Aβ42/40 ratios provide similar clinical information in the assessment of amyloid pathology.