Is plasma p-tau217 as useful as CSF for Alzheimer PET positivity?
In 114 Geneva memory-clinic patients, plasma p-tau217 identified amyloid/tau PET positivity (mean AUC 0.96) better than p-tau181/231 and similarly to CSF p-tau217 (AUC 0.95).
Source
Head-to-head study of diagnostic accuracy of plasma and cerebrospinal fluid p-tau217 versus p-tau181 and p-tau231 in a memory clinic cohort
Study at a glance
- Design
- Cross-sectional — Head-to-head diagnostic-accuracy study of plasma and CSF p-tau217 vs p-tau181 and p-tau231 against amyloid- and tau-PET in a Geneva memory-clinic cohort.
- N
- N=114 · 114 participants (CU 33, MCI 67, dementia 14); CSF subset n=36.
- Population
- Memory-clinic patients at Geneva University Hospitals spanning cognitively unimpaired, MCI, and dementia.
- Outcome
- Correlation with A/T-PET, group effect sizes, and ROC AUC for amyloid- and tau-PET positivity.
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Is plasma p-tau217 as useful as CSF for Alzheimer PET positivity?
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
114 participants: CU 33, MCI 67, dementia 14.
The study included 114 participants (CU = 33; MCI = 67; Dementia = 14).
Plasma p-tau217 mean AUC for A/T-PET positivity was 0.96 vs 0.76 and 0.79.
ROC curves to identify A-PET and T-PET positivity (AUC average : p -tau217 = 0.96; p -tau181 = 0.76; p -tau231 = 0.79)
What they did
Correlated plasma and CSF p-tau217/181/231 with continuous amyloid- and tau-PET, compared effect sizes across diagnosis and A/T groups, and ran ROC analyses for PET positivity.
What they found
Plasma/CSF p-tau217 correlated more strongly with A- and T-PET (r 0.64–0.83) than p-tau181 or p-tau231. Plasma p-tau217 had larger group δ (0.55–0.96) and mean AUC 0.96 vs 0.76 (181) and 0.79 (231). CSF p-tau217 AUC 0.95 did not significantly beat CSF 181/231 (0.88/0.89). Authors conclude plasma p-tau217 performed like CSF and could reduce invasive testing.
The limits
What it doesn't show
CSF n=36 is too small for a firm plasma-vs-CSF contest, and cohort-specific cut-offs plus a single memory clinic limit transportability.
Key terms
- p-tau217
- Tau phosphorylated at threonine 217; best plasma marker here for A/T-PET.
- p-tau181 / p-tau231
- Comparator phospho-tau epitopes with lower plasma AUCs in this cohort.
- A-PET / T-PET
- Amyloid and tau positron-emission tomography used as imaging standards.
- AUC
- Area under the ROC curve for PET positivity; plasma p-tau217 mean AUC 0.96.
- MCI
- Mild cognitive impairment; 67 of 114 participants.
- Simoa / MSD
- Homebrew Simoa (181/231) and Lilly MSD immunoassay (217) platforms.
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Memory-clinic n was:
Common questions
How many participants?
114 (33 cognitively unimpaired, 67 MCI, 14 dementia).
Plasma p-tau217 mean AUC vs PET?
0.96, versus 0.76 (181) and 0.79 (231).
Did CSF p-tau217 beat other CSF epitopes?
Not significantly (AUC 0.95 vs 0.88 and 0.89).
Main CSF limitation?
Only 36 people had CSF, limiting plasma–CSF comparison.
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