Elecsys CSF biomarker immunoassays demonstrate concordance with amyloid-PET imaging

Background: beta-amyloid (A beta) positron emission tomography (PET) imaging is currently the only Food and Drug Administration-approved method to support clinical diagnosis of Alzheimer's disease (AD). However, numerous research studies support the use of cerebrospinal fluid (CSF) biomarkers, as a cost-efficient, quick and equally valid method to define AD pathology. Methods: Using automated Elecsys (R) assays (Roche Diagnostics) for A beta (1-42) (A beta 42), A beta (1-40) (A beta 40), total tau (tTau) and phosphorylated tau (181P) (pTau), we examined CSF samples from 202 participants of the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of ageing cohort, to demonstrate the concordance with pathological AD via PET imaging. Results: Ratios A beta 42/A beta 40, tTau/A beta 42 and pTau/A beta 42 had higher receiver operator characteristic-area under the curve (all 0.94), and greater concordance with A beta-PET (overall percentage agreement similar to 90%), compared with individual biomarkers. Conclusion: Strong concordance between CSF biomarkers and A beta-PET status was observed overall, including for cognitively normal participants, further strengthening the association between these markers of AD neuropathological burden for both developmental research studies and for use in clinical trials.