Long term clinical performance and analytical robustness of the Lumipulse plasma p‐tau217 assay in routine clinical practice

Abstract INTRODUCTION Plasma phosphorylated tau 217 (p‑tau217) immunoassays are increasingly being used to assess Alzheimer's disease (AD) pathology despite limited data affirming test reliability over time. METHODS Clinical performance of the Fujirebio Lumipulse G p‑tau217 assay was assessed in 744 Mayo Clinic patients presenting for evaluation of cognitive impairment between July 2024 and December 2025. Cerebrospinal fluid p‑tau181/amyloid beta 42 or amyloid positron emission tomography, within 1 year of p‐tau217 testing, were used as reference. Analytical robustness was evaluated by tracking result frequencies over time, conducting quality control checks, performing 10 lot‑to‑lot comparisons, and comparing two versions of reagents. RESULTS Diagnostic accuracy for detection of AD pathology was 93% (95% confidence interval 91–95) with 23% intermediate results. Reduced estimated glomerular filtration rate was associated with increased intermediate results among amyloid‐negative individuals. Result frequencies remained stable, average imprecision was 8%, and analytical bias between lots and version changes were ≤ 11%. DISCUSSION The findings support plasma p‐tau217 reliability in clinical practice for evaluation of cognitively impaired individuals.