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Considering Questions Before Methods in Dementia Research With Competing Events and Causal Goals
Rojas-Saunero LP, Young JG, Didelez V, Ikram MA, Swanson SA.. American journal of epidemiology, 2023-08-01
Topic: Risk, prevention and care in population studies
Studying causal exposure effects on dementia is challenging when death is a competing event. Researchers often interpret death as a potential source of bias, although bias cannot be defined or assessed if the causal question is not explicitly specified. Here we discuss 2 possible notions of a causal effect on dementia risk: the "controlled direct effect" and the "total effect." We provide definitions and discuss the "censoring" assumptions needed for identification in either case and their link to familiar statistical methods.
Key findings
- Researchers often interpret death as a potential source of bias, although bias cannot be defined or assessed if the causal question is not explicitly specified.
- Here we discuss 2 possible notions of a causal effect on dementia risk: the "controlled direct effect" and the "total effect." We provide definitions and discuss the "censoring" assumptions needed for identification in either case and their link to familiar statistical methods.
- We illustrate concepts in a hypothetical randomized trial on smoking cessation in late midlife, and emulate such a trial using observational data from the Rotterdam Study, the Netherlands, 1990-2015.
- We estimated a total effect of smoking cessation (compared with continued smoking) on 20-year dementia risk of 2.1 (95% confidence interval: -0.1, 4.2) percentage points and a controlled direct effect of smoking cessation on 20-year dementia risk had death been prevented of -2.7 (95% confidence interval: -6.1, 0.8) percentage points.
Why it matters
This is a methodological paper discussing how to define and study causal effects on dementia risk when death is a competing event. It offers no treatment, cure, or prevention and is about research methods rather than patient care.
Study details
- Study designrandomized controlled trial
- Evidence strengthHigh
How this study scored 68/100
Published in a peer-reviewed journal, and it is a randomised controlled trial. Scored zero for sample size, effect reported and studied in people because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (American journal of epidemiology) |
| Journal's citation record | 3 / 4 | American Journal of Epidemiology: journal h-index 416 (OpenAlex, 2026-10-29) |
| Study design | 11 / 12 | A randomised controlled trial |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2023 — within 6 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 1 / 2 | Randomised (as stated in the record) |
| Times cited | 4 / 7 | Cited 71 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 14.2 citations a year over 5 year(s) since 2023 |
| Impact for its field and year | 4 / 6 | Cited 14.1× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 10 other studies in this library |
| Still being cited | 3 / 4 | Cited 64 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Sonja A. Swanson: h-index 22 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | Harvard University: institution h-index 3,235 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 7 institution(s) in 3 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 37139580) |
| Free to read | 2 / 2 | Free to read |
| Total | 68 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
- DOI: 10.1093/aje/kwad090
- PubMed: 37139580
- Original source →
- Free full text: American Journal of Epidemiology →
Full text: free to read — OpenAlex lists this copy as free to read: the link above (checked 6 Feb 1020).
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. Check the citation against the original before you use it.
APA 7th
Rojas-Saunero, L. P., Young, J. G., Didelez, V., Ikram, M. A., & Swanson, S. A. (2023). Considering Questions Before Methods in Dementia Research With Competing Events and Causal Goals. American journal of epidemiology. https://doi.org/10.1093/aje/kwad090
Vancouver
Rojas-Saunero LP, Young JG, Didelez V, Ikram MA, Swanson SA. Considering Questions Before Methods in Dementia Research With Competing Events and Causal Goals. American journal of epidemiology. 2023. doi:10.1093/aje/kwad090. PMID: 37139580.
BibTeX
@article{rojassaunero2023-37139580,
author = {Rojas-Saunero, L. P. and Young, J. G. and Didelez, V. and Ikram, M. A. and Swanson, S. A.},
title = {{Considering Questions Before Methods in Dementia Research With Competing Events and Causal Goals}},
journal = {American journal of epidemiology},
year = {2023},
doi = {10.1093/aje/kwad090},
pmid = {37139580},
url = {https://doi.org/10.1093/aje/kwad090}
}
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