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Study of the utility and impact of a plasma p-tau181 Alzheimer's biomarker (SUITABLE)
O'Brien K, Coykendall C, Harkins K, Wang X, Perelman A, Zhang M, Karlawish J. Alzheimer's & Dementia: Translational Research & Clinical Interventions, 2026-03-13
Topic: Amyloid, tau and blood-test diagnosis
Introduction Blood-based Alzheimer's disease (AD) biomarkers are increasingly used in clinical care, but there are few real-world studies of their clinical utility. We evaluated the impact of plasma phosphorylated tau at threonine 181 (p-tau181) on the diagnosis and management of patients with cognitive impairment in a memory clinic. Methods Dementia specialists referred patients for plasma p-tau181 testing during clinical care. We used surveys and chart review to assess the impact of plasma p-tau181 testing on clinical care and patient and care partner wellbeing. We assessed co-primary outcomes of (1) change in diagnostic confidence before vs after testing, (2) change in diagnosis, and (3) change in management. A diagnosis or management change of greater than 30% was considered to be clinically significant. Secondary and exploratory outcomes included impact of plasma p-tau181 testing on the use of additional diagnostics and impact on patient and care partner psychological wellbeing, health behaviors, and future planning. Results One hundred patients completed plasma p-tau181 testing; 81% had an elevated result, and 19% had a non-elevated result. Clinician diagnostic confidence averaged 1.43 points higher after p-tau181 testing (95% confidence interval [CI] 1.02 to 1.84, p p = 0.31) of patients had a change in management and 17.2% of patients had a change in diagnosis - significantly lower than the 30% threshold (95% CI 9.5% to 24.9%, p = 0.004). Patients with elevated results were less likely to have a diagnosis changed after testing than those with non-elevated results (OR 0.08 [95% CI 0.01 to 0.47], p = 0.005). A non-elevated result was associated with decreased use of amyloid positron emission tomography (PET) (odds ratio [OR] 0.25 [95% CI 0.07 to 0.86], p = 0.028). Patients with an elevated result had higher anxiety at 2 to 3 months after disclosure ( p = 0.01). Discussion Non-elevated plasma p-tau181 results impacted the diagnosis and use of amyloid PET imaging in a memory clinic. There was increased anxiety in patients after testing, affirming the need for post-disclosure psychological support.
Key findings
- A diagnosis or management change of greater than 30% was considered to be clinically significant.
- Results One hundred patients completed plasma p-tau181 testing; 81% had an elevated result, and 19% had a non-elevated result.
- Clinician diagnostic confidence averaged 1.43 points higher after p-tau181 testing (95% confidence interval [CI] 1.02 to 1.84, p < 0.0001).
- Patients with elevated results were less likely to have a diagnosis changed after testing than those with non-elevated results (OR 0.08 [95% CI 0.01 to 0.47], p = 0.005).
- A non-elevated result was associated with decreased use of amyloid positron emission tomography (PET) (odds ratio [OR] 0.25 [95% CI 0.07 to 0.86], p = 0.028).
Why it matters
Plasma p-tau181 testing raised clinicians' diagnostic confidence, but changes in diagnosis and management were below the study's 30% threshold for clinical significance. This suggests limited impact on care in this memory clinic, and it is not a treatment or cure.
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Study details
- Study designcohort
- Participants100
- Effect sizeDiagnostic confidence +1.43 points; diagnosis changed in 17.2%, management in 27.7%
- Evidence strengthEarly
Limitations
The prevalence of AD at the memory centre is much higher than in general neurology or primary care, so few non-elevated results were observed; an elevated result could not be used as confirmation of the presence of pathology; and patients were referred by specialists using clinical judgment.
How this study scored 49/100
Published in a peer-reviewed 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 and free to read, so those were left out: it earned 46 of the 94 points we could judge it on, which is 49 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Alzheimer's & Dementia: Translational Research & Clinical Interventions) |
| 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 | 2 / 5 | Rated “early” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 2 / 4 | 100 participants |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| 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 | 0 / 7 | Cited 0 times (OpenAlex, 2026-10-10) |
| Citations per year | 0 / 5 | 0.0 citations a year over 2 year(s) since 2026 |
| Impact for its field and year | 0 / 6 | Cited 0.0× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 0 / 4 | Cited 0 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 3 / 4 | Last-listed author Jason H. Karlawish: h-index 88 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University of Pennsylvania: institution h-index 1,859 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 2 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 42254757) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 46 / 94 | Scored on 18 of 20 parts. We have no data for the rest, so they are left out: 46 of the 94 points we could judge it on is 49 out of 100. |
| Total | 49 / 100 | — |
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Read the original
Full text: free to read — PubMed Central lists this copy as free to read: the link above (checked 10 Oct 2026).
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. The record names 7 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
O'Brien, K., Coykendall, C., Harkins, K., Wang, X., Perelman, A., Zhang, M., et al. (2026). Study of the utility and impact of a plasma p-tau181 Alzheimer's biomarker (SUITABLE). Alzheimer's & Dementia: Translational Research & Clinical Interventions. https://doi.org/10.1002/trc2.70207
Vancouver
O'Brien K, Coykendall C, Harkins K, Wang X, Perelman A, Zhang M, et al. Study of the utility and impact of a plasma p-tau181 Alzheimer's biomarker (SUITABLE). Alzheimer's & Dementia: Translational Research & Clinical Interventions. 2026. doi:10.1002/trc2.70207. PMID: 42254757.
BibTeX
@article{obrien2026-42254757,
author = {O'Brien, K. and Coykendall, C. and Harkins, K. and Wang, X. and Perelman, A. and Zhang, M. and Karlawish, J.},
title = {{Study of the utility and impact of a plasma p-tau181 Alzheimer's biomarker (SUITABLE)}},
journal = {Alzheimer's \& Dementia: Translational Research \& Clinical Interventions},
year = {2026},
doi = {10.1002/trc2.70207},
pmid = {42254757},
url = {https://doi.org/10.1002/trc2.70207}
}
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