Topic: Brain imaging, connectivity and assessment
Risk prediction in Alzheimer disease can guide follow-up, biomarker testing, trial referral, and prognostic counseling. Clinical use of an estimated 24-month probability requires both useful ranking and a probability scale that retains its meaning when the population changes. We studied 1,002 ADNI participants with mild cognitive impairment using 11 age-adjusted models trained and calibrated in ADNI1 and transported to ADNI2, then reversed the experiment. In ADNI2, transported models had slightly higher AUC than locally developed models (0.840 vs 0.816) and substantially worse ICI (0.151 vs 0.043; slope 2.283). The reverse experiment produced the same separation in ADNI1 (AUC 0.727 vs 0.694; ICI 0.155 vs 0.045; slope 0.823). Removing ADAS strengthened the contrast: AUC rose by 0.229 while ICI worsened by 0.105. Ranking and absolute risk separated across study phases. The results extend calibration-drift research to Alzheimer disease and support revalidation of probability scales when recruitment, disease mix, or measurement practice changes.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Ewing, M. A. (2026). Alzheimer disease risk estimates lose clinical calibration across study phases despite useful patient ranking. Research Square. https://doi.org/10.21203/rs.3.rs-10898531/v1
Vancouver
Ewing MA. Alzheimer disease risk estimates lose clinical calibration across study phases despite useful patient ranking. Research Square. 2026. doi:10.21203/rs.3.rs-10898531/v1.
BibTeX
@article{ewing2026-6dd97f86,
author = {Ewing, M. A.},
title = {{Alzheimer disease risk estimates lose clinical calibration across study phases despite useful patient ranking}},
journal = {Research Square},
year = {2026},
doi = {10.21203/rs.3.rs-10898531/v1},
url = {https://doi.org/10.21203/rs.3.rs-10898531/v1}
}
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Key findings
- The results extend calibration-drift research to Alzheimer disease and support revalidation of probability scales when recruitment, disease mix, or measurement practice changes.
Study details
- Participants1,002
- Effect sizeAUC 0.727
- Evidence strengthLow
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 35 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for study design and randomised / blinded because the record does not state it. We have no data on 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 and multi-centre collaboration, so those were left out: it earned 22 of the 62 points we could judge it on, which is 35 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (Research Square) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 3 / 4 | 1,002 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 | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 22 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 22 of the 62 points we could judge it on is 35 out of 100. |
| Total | 35 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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