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An alternative method for estimating efficacy of the AN1792 vaccine for Alzheimer disease
Koepsell TD, Chi YY, Zhou XH, Lee WW, Ramos EM, Kukull WA.. Neurology, 2007-11-01
Topic: Amyloid, tau and blood-test diagnosis
Background In a randomized trial of AN1792 vaccine against A beta in Alzheimer disease (AD), only 20% of vaccine recipients had an anti-AN1792 antibody response. The trialists sought to estimate the efficacy of the vaccine among antibody responders by comparing outcomes among antibody responders in the vaccine group with outcomes among all placebo recipients. Methods We describe why the method used may be biased. An alternative approach to estimating efficacy is described that compares outcomes between responders in the vaccine group and potential responders in the placebo group. Although potential responders cannot be identified individually, the distribution of outcomes among them can be inferred indirectly, under certain assumptions. Three methods for assessing vaccine effects are compared using data on the ventricular volume boundary shift integral (BSI) from the AN1792 trial and in simulations. Results Mean (+/- standard error) increase in BSI relative to controls was 0.16 (+/-0.065) by intent-to-treat, 0.61 (+/-0.116) in the published comparison, and 0.81 (+/-0.320) in the proposed approach. Simulations show that the published method can often yield biased estimates, while the proposed method does not. Conclusions Published results from the AN1792 trial may have underestimated the effect of vaccine on progression of cerebral atrophy among patients with an antibody response to the vaccine. For this and future similar trials, we suggest that intent-to-treat results always be reported, and that efficacy estimates be based on the proposed potential-outcomes method.
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APA 7th
Koepsell, T. D., Chi, Y. Y., Zhou, X. H., Lee, W. W., Ramos, E. M., & Kukull, W. A. (2007). An alternative method for estimating efficacy of the AN1792 vaccine for Alzheimer disease. Neurology. https://doi.org/10.1212/01.wnl.0000278226.96003.f8
Vancouver
Koepsell TD, Chi YY, Zhou XH, Lee WW, Ramos EM, Kukull WA. An alternative method for estimating efficacy of the AN1792 vaccine for Alzheimer disease. Neurology. 2007. doi:10.1212/01.wnl.0000278226.96003.f8. PMID: 17984455.
BibTeX
@article{koepsell2007-17984455,
author = {Koepsell, T. D. and Chi, Y. Y. and Zhou, X. H. and Lee, W. W. and Ramos, E. M. and Kukull, W. A.},
title = {{An alternative method for estimating efficacy of the AN1792 vaccine for Alzheimer disease}},
journal = {Neurology},
year = {2007},
doi = {10.1212/01.wnl.0000278226.96003.f8},
pmid = {17984455},
url = {https://doi.org/10.1212/01.wnl.0000278226.96003.f8}
}
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.
Key findings
- Results Mean (+/- standard error) increase in BSI relative to controls was 0.16 (+/-0.065) by intent-to-treat, 0.61 (+/-0.116) in the published comparison, and 0.81 (+/-0.320) in the proposed approach.
- Conclusions Published results from the AN1792 trial may have underestimated the effect of vaccine on progression of cerebral atrophy among patients with an antibody response to the vaccine.
- For this and future similar trials, we suggest that intent-to-treat results always be reported, and that efficacy estimates be based on the proposed potential-outcomes method.
Why it matters
This analysis re-examined data from the AN1792 vaccine trial and suggests the published method may have underestimated the vaccine's effect on brain atrophy among antibody responders. It is a statistical methods study, not new evidence that the vaccine is effective or safe.
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Study details
- Study designrandomized controlled trial
- Evidence strengthHigh
How this study scored 54/100
Published in a leading specialty journal, and it is a randomized 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 | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| Study design | 11 / 12 | A randomized 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 | 1 / 5 | 2007 — within 20 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) |
| Randomized / blinded | 1 / 2 | Randomized (as stated in the record) |
| Times cited | 2 / 7 | Cited 9 times (OpenAlex, 2026-10-10) |
| Citations per year | 0 / 5 | 0.4 citations a year over 21 year(s) since 2007 |
| Impact for its field and year | 1 / 6 | Cited 0.2× 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 1 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Walter A. Kukull: h-index 107 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | University of Washington: institution h-index 3,540 (OpenAlex) |
| Multicenter collaboration | 1 / 3 | OpenAlex lists 2 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 17984455) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 54 / 100 | — |
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