Multicenter validation of plasma p‐tau217/ amyloid beta 1‐42 ratio in symptomatic Alzheimer's disease

INTRODUCTION: G pTau 217/β-Amyloid 1-42 Plasma Ratio to detect amyloid positivity in patients with cognitive decline symptoms. METHODS: The Lumipulse Plasma Ratio was evaluated using predetermined thresholds (≤0.00370 negative; ≥0.00738 positive) against cerebrospinal fluid (CSF) biomarker ratios or amyloid positron emission tomography (PET) imaging as references in 499 adults (≥50 years old) enrolled in prospective studies conducted across academic memory clinics and research centers. RESULTS: Amyloid status was determined by CSF in 347 patients (189 positive [54.5%]) and by PET imaging in 152 patients (66 positive [43.4%]). The Lumipulse Plasma Ratio was positive in 219 patients (43.9%), negative in 182 (36.5%), and indeterminate in 98 (19.6%). Positive and negative predictive values were 91.8% and 97.3%, with a sensitivity and specificity of 97.6% and 90.8%, respectively. DISCUSSION: The US Food and Drug Administration-cleared Lumipulse Plasma Ratio demonstrated high accuracy in identifying amyloid pathology and offers an alternative to CSF testing and amyloid PET imaging.