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Prognostic heterogeneity within cognitive stages: a nationwide cohort study of everyday functional difficulties and mortality in 202,508 older adults
Chi W, Liou T, Wang W, Yen C, Liao H, Huang WW.. Research Square, 2026-10-23
Topic: Health services, long-term care and technology
Background Prognosis varies widely within a Clinical Dementia Rating (CDR) stage; everyday function may explain part of it. Aims To quantify how mortality differs within a CDR stage according to everyday functional difficulty. Methods Retrospective cohort of 202,508 adults aged ≥ 65 years with CDR 1–3 cognitive impairment in Taiwan’s disability registry (2012–2024), assessed with the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) and linked to death records. Cox models adjusted for age, sex, education, urbanicity, and CDR ranked eleven Mobility and Cognition items; the leading four were counted when rated at least moderately difficult. Mortality was estimated by Kaplan–Meier. Results Over a median 2.43 years, 96,130 (47.5%) died. The strongest independent associations were with rising from sitting, concentrating for 10 minutes, understanding speech, and standing for 30 minutes. Within every CDR stage, three-year mortality roughly doubled from none of these four difficulties to all four: 21.0% to 41.0% at CDR 1 and 26.8% to 59.0% at CDR 3; the adjusted hazard ratio per difficulty rose from 1.19 to 1.33. The count raised the C-index from 0.639 to 0.656. Unadjusted, mortality at CDR 1 with all four (41.0%) exceeded that at CDR 3 with none (26.8%). Discussion Cognitive staging and everyday function are not interchangeable. The gradient was steepest at the most advanced stage despite near-ceiling responses, and persisted, attenuated, in 2019–2024. Conclusions Four questions already recorded at assessment identify, within one cognitive stage, groups whose three-year mortality differs about two-fold.
Key findings
- Results Over a median 2.43 years, 96,130 (47.5%) died.
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Study details
- Study designretrospective cohort
- Participants202,508
- Effect size47.5%; 21.0% to 41.0%; 26.8% to 59.0%
- Evidence strengthModerate
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 50 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for 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 31 of the 62 points we could judge it on, which is 50 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 | 7 / 12 | A retrospective cohort study, reconstructed from past records |
| Strength of evidence | 3 / 5 | Rated “moderate” 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 | 4 / 4 | 202,508 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 | — / 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 | 31 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 31 of the 62 points we could judge it on is 50 out of 100. |
| Total | 50 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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APA 7th
Chi, W., Liou, T., Wang, W., Yen, C., Liao, H., & Huang, W. W. (2026). Prognostic heterogeneity within cognitive stages: a nationwide cohort study of everyday functional difficulties and mortality in 202,508 older adults. Research Square. https://doi.org/10.21203/rs.3.rs-11248817/v1
Vancouver
Chi W, Liou T, Wang W, Yen C, Liao H, Huang WW. Prognostic heterogeneity within cognitive stages: a nationwide cohort study of everyday functional difficulties and mortality in 202,508 older adults. Research Square. 2026. doi:10.21203/rs.3.rs-11248817/v1.
BibTeX
@article{chi2026-ca10c8ff,
author = {Chi, W. and Liou, T. and Wang, W. and Yen, C. and Liao, H. and Huang, W. W.},
title = {{Prognostic heterogeneity within cognitive stages: a nationwide cohort study of everyday functional difficulties and mortality in 202,508 older adults}},
journal = {Research Square},
year = {2026},
doi = {10.21203/rs.3.rs-11248817/v1},
url = {https://doi.org/10.21203/rs.3.rs-11248817/v1}
}
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