# A two-step workflow based on plasma p-tau217 to screen for amyloid β positivity with further confirmatory testing only in uncertain cases

Article · Brum WS, Cullen NC, Janelidze S, Ashton NJ, Zimmer ER, Therriault J, Benedet AL, Rahmouni N, Tissot C, Stevenson J, Servaes S, Triana-Baltzer G, Kolb HC, Palmqvist S, Stomrud E, Rosa-Neto P, Blennow K, Hansson O

- Archive id: doi:10.1038/s43587-023-00471-5
- Published: 2023-08-31
- Venue: Nature aging
- DOI: https://doi.org/10.1038/s43587-023-00471-5
- PMID: 37653254
- PMCID: PMC10501903
- Citations: 233
- Source URL: https://doi.org/10.1038/s43587-023-00471-5
- PDF: https://europepmc.org/articles/PMC10501903/pdf
- Provenance: europepmc

## Abstract

Cost-effective strategies for identifying amyloid-β (Aβ) positivity in patients with cognitive impairment are urgently needed with recent approvals of anti-Aβ immunotherapies for Alzheimer's disease (AD). Blood biomarkers can accurately detect AD pathology, but it is unclear whether their incorporation into a full diagnostic workflow can reduce the number of confirmatory cerebrospinal fluid (CSF) or positron emission tomography (PET) tests needed while accurately classifying patients. We evaluated a two-step workflow for determining Aβ-PET status in patients with mild cognitive impairment (MCI) from two independent memory clinic-based cohorts (n = 348). A blood-based model including plasma tau protein 217 (p-tau217), age and APOE ε4 status was developed in BioFINDER-1 (area under the curve (AUC) = 89.3%) and validated in BioFINDER-2 (AUC = 94.3%). In step 1, the blood-based model was used to stratify the patients into low, intermediate or high risk of Aβ-PET positivity. In step 2, we assumed referral only of intermediate-risk patients to CSF Aβ42/Aβ40 testing, whereas step 1 alone determined Aβ-status for low- and high-risk groups. Depending on whether lenient, moderate or stringent thresholds were used in step 1, the two-step workflow overall accuracy for detecting Aβ-PET status was 88.2%, 90.5% and 92.0%, respectively, while reducing the number of necessary CSF tests by 85.9%, 72.7% and 61.2%, respectively. In secondary analyses, an adapted version of the BioFINDER-1 model led to successful validation of the two-step workflow with a different plasma p-tau217 immunoassay in patients with cognitive impairment from the TRIAD cohort (n = 84). In conclusion, using a plasma p-tau217-based model for risk stratification of patients with MCI can substantially reduce the need for confirmatory testing while accurately classifying patients, offering a cost-effective strategy to detect AD in memory clinic settings.

_Abstract reproduced under CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)._

Topics: [Alzheimer's, Parkinson's & Neurodegeneration](https://space-kitty.com/topics/neurodegeneration)

Cited in dossiers:
- [Alzheimer's, Parkinson's & Neurodegeneration: State of the Field (October 2026)](https://space-kitty.com/dossiers/neurodegeneration)

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