Accuracy of cerebrospinal fluid biomarker ratios to determine amyloid positron‐emission tomography status: a diagnostic test accuracy meta‐analysis

All three CSF biomarker ratios (Aβ42/Aβ40, pTau/Aβ42, and tTau/Aβ42) analyzed were highly concordant with amyloid PET. However, the pTau/Aβ42 ratio consistently showed higher concordance with amyloid PET positivity than the Aβ42/Aβ40 or tTau/Aβ42 ratio across multiple analysis methods, suggesting that pTau/Aβ42 may be the preferred CSF biomarker ratio for confirmation of the diagnosis of AD.