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Cross-cohort validation and cutpoint estimation of the Janssen plasma p-tau217+ assay in predominantly cognitively normal community studies
Wasiu G Balogun, Xuemei Zeng, Gallen Triana-Baltzer, Anum Saeed, Happiness E Aigbogun, Alexandra Gogola, Brian J Lopresti, Victor L Villemagne et al.. Alzheimer's & dementia : the journal of the Alzheimer's Association, 2025-11
Topic: Plasma and spinal-fluid biomarkers
The cohorts had low pre-test probability (%Aβ positivity = 14.9-24.7) and were predominantly cognitively normal (> 73%). Plasma p-tau217+ had high accuracy for abnormal Aβ PET (areas under the curve [AUCs] = 81-86%), good correlation with Aβ-PET burden (0.336-0.397) that was highest in the cohort with the most Aβ-PET-positive participants, and the biomarker concentrations were highest in the joint Aβ-PET and tau-PET positive group. Negative predictive value (NPV) was high across cohorts (≤93%) but positive predictive value (PPV) was consistently poor (< 57%). Sensitivity and specificity averaged 75% and 84%, respectively. A combined cohort cutpoint of 0.05pg/ml gave AUC = 84.5%, NPV = 94%, PPV = 50%, sensitivity = 75%, and specificity = 84%. Plasma p-tau217+ can rule out Aβ pathophysiology due to Alzheimer's disease at the population level. Cohort-level %Aβ-PET positivity influences accuracies. HIGHLIGHTS: Plasma phosphorylated tau (p-tau) 217 assays have demonstrated potential to identify older adults with brain amyloid pathology due to Alzheimer's disease. Community-based studies are crucial for accessing the clinical validity of fluid biomarkers and their real-world applicability. We evaluated the Janssen plasma p-tau217+ assay in three community-based cohorts. Janssen plasma p-tau217+ identified amyloid-beta abnormalities across three diverse cohorts of community-dwelling older adults. High NPV indicates p-tau217+ as a good tool for initial screening to enrich for high-risk individuals particularly for cohort studies and clinical trial participation.
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APA 7th
Balogun, W. G., Zeng, X., Triana-Baltzer, G., Saeed, A., Aigbogun, H. E., Gogola, A., et al. (2025). Cross-cohort validation and cutpoint estimation of the Janssen plasma p-tau217+ assay in predominantly cognitively normal community studies. Alzheimer's & dementia : the journal of the Alzheimer's Association. https://doi.org/10.1002/alz.70916
Vancouver
Balogun WG, Zeng X, Triana-Baltzer G, Saeed A, Aigbogun HE, Gogola A, et al. Cross-cohort validation and cutpoint estimation of the Janssen plasma p-tau217+ assay in predominantly cognitively normal community studies. Alzheimer's & dementia : the journal of the Alzheimer's Association. 2025. doi:10.1002/alz.70916. PMID: 41273220.
BibTeX
@article{balogun2025-41273220,
author = {Balogun, Wasiu G and Zeng, Xuemei and Triana-Baltzer, Gallen and Saeed, Anum and Aigbogun, Happiness E and Gogola, Alexandra and Lopresti, Brian J and Villemagne, Victor L and others},
title = {{Cross-cohort validation and cutpoint estimation of the Janssen plasma p-tau217+ assay in predominantly cognitively normal community studies}},
journal = {Alzheimer's \& dementia : the journal of the Alzheimer's Association},
year = {2025},
doi = {10.1002/alz.70916},
pmid = {41273220},
url = {https://doi.org/10.1002/alz.70916}
}
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Key findings
- The cohorts had low pre-test probability (%Aβ positivity = 14.9-24.7) and were predominantly cognitively normal (> 73%).
- Plasma p-tau217+ had high accuracy for abnormal Aβ PET (areas under the curve [AUCs] = 81-86%), good correlation with Aβ-PET burden (0.336-0.397) that was highest in the cohort with the most Aβ-PET-positive participants, and the biomarker concentrations were highest in the joint Aβ-PET and tau-PET positive group.
- Negative predictive value (NPV) was high across cohorts (≤93%) but positive predictive value (PPV) was consistently poor (< 57%).
- Sensitivity and specificity averaged 75% and 84%, respectively.
- A combined cohort cutpoint of 0.05pg/ml gave AUC = 84.5%, NPV = 94%, PPV = 50%, sensitivity = 75%, and specificity = 84%.
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Study details
- Study designcohort study
- Participants441
- Effect sizeAUC = 84.5
- Evidence strengthModerate
How this study scored 77/100
Published in a leading specialty journal, and it is a cohort study following people over time. Scored zero for randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 43 of the 56 points we could judge it on, which is 77 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Alzheimer's & dementia : the journal of the Alzheimer's Association) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 7 / 12 | A cohort study following people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 2 / 4 | 441 participants |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41273220) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 43 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 43 of the 56 points we could judge it on is 77 out of 100. |
| Total | 77 / 100 | — |
What each of these 20 components measures, and what this score is not →
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