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Using a distribution-based approach and systematic review methods to derive minimum clinically important differences
Watt JA, Veroniki AA, Tricco AC, Straus SE.. BMC medical research methodology, 2021-02-26
Topic: Risk, prevention and care in population studies
Background Clinical interpretation of changes measured on a scale is dependent on knowing the minimum clinically important difference (MCID) for that scale: the threshold above which clinicians, patients, and researchers perceive an outcome difference. Until now, approaches to determining MCIDs were based upon individual studies or surveys of experts. However, the comparison of meta-analytic treatment effects to a MCID derived from a distribution of standard deviations (SDs) associated with all trial-specific outcomes in a meta-analysis could improve our clinical understanding of meta-analytic treatment effects. Methods We approximated MCIDs using a distribution-based approach that pooled SDs associated with baseline mean or mean change values for two scales (i.e. Mini-Mental State Exam [MMSE] and Alzheimer Disease Assessment Scale - Cognitive Subscale [ADAS-Cog]), as reported in parallel randomized trials (RCTs) that were included in a systematic review of cognitive enhancing medications for dementia (i.e. cholinesterase inhibitors and memantine). We excluded RCTs that did not report baseline or mean change SD values. We derived MCIDs at 0.4 and 0.5 SDs of the pooled SD and compared our derived MCIDs to previously published MCIDs for the MMSE and ADAS-Cog. Results We showed that MCIDs derived from a distribution-based approach approximated published MCIDs for the MMSE and ADAS-Cog. For the MMSE (51 RCTs, 12,449 patients), we derived a MCID of 1.6 at 0.4 SDs and 2 at 0.5 SDs using baseline SDs and we derived a MCID of 1.4 at 0.4 SDs and 1.8 at 0.5 SDs using mean change SDs. For the ADAS-Cog (37 RCTs, 10,006 patients), we derived a MCID of 4 at 0.4 SDs and 5 at 0.5 SDs using baseline SDs and we derived a MCID of 2.6 at 0.4 SDs and 3.2 at 0.5 SDs using mean change SDs. Conclusion A distribution-based approach using data included in a systematic review approximated known MCIDs. Our approach performed better when we derived MCIDs from baseline as opposed to mean change SDs. This approach could facilitate clinical interpretation of outcome measures reported in RCTs and systematic reviews of interventions. Future research should focus on the generalizability of this method to other clinical scenarios.
Key findings
- However, the comparison of meta-analytic treatment effects to a MCID derived from a distribution of standard deviations (SDs) associated with all trial-specific outcomes in a meta-analysis could improve our clinical understanding of meta-analytic treatment effects.
- Methods We approximated MCIDs using a distribution-based approach that pooled SDs associated with baseline mean or mean change values for two scales (i.e.
- Results We showed that MCIDs derived from a distribution-based approach approximated published MCIDs for the MMSE and ADAS-Cog.
Why it matters
This methods paper used data from trials of cognitive-enhancing medications for dementia to estimate the smallest meaningful change on cognitive scales. It does not test a treatment or report new results about preventing or curing Alzheimer disease.
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Study details
- Study designsystematic review
- Participants12,449
- Evidence strengthHigh
How this study scored 71/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for effect reported because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (BMC medical research methodology) |
| Journal's citation record | 2 / 4 | BMC Medical Research Methodology: journal h-index 221 (OpenAlex, 2026-10-29) |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| 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 | 2021 — within 6 year(s) of the newest study here |
| Sample size | 4 / 4 | 12,449 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | 5 / 7 | Cited 160 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 22.9 citations a year over 7 year(s) since 2021 |
| Impact for its field and year | 1 / 6 | Cited 0.7× 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 | 3 / 4 | Cited 120 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Sharon Elizabeth Straus: h-index 114 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University of Toronto: institution h-index 1,923 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 5 institution(s) in 3 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 33637039) |
| Free to read | 2 / 2 | Free to read |
| Total | 71 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
- DOI: 10.1186/s12874-021-01228-7
- PubMed: 33637039
- Original source →
- Free full text: BMC Medical Research Methodology →
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
Watt, J. A., Veroniki, A. A., Tricco, A. C., & Straus, S. E. (2021). Using a distribution-based approach and systematic review methods to derive minimum clinically important differences. BMC medical research methodology. https://doi.org/10.1186/s12874-021-01228-7
Vancouver
Watt JA, Veroniki AA, Tricco AC, Straus SE. Using a distribution-based approach and systematic review methods to derive minimum clinically important differences. BMC medical research methodology. 2021. doi:10.1186/s12874-021-01228-7. PMID: 33637039.
BibTeX
@article{watt2021-33637039,
author = {Watt, J. A. and Veroniki, A. A. and Tricco, A. C. and Straus, S. E.},
title = {{Using a distribution-based approach and systematic review methods to derive minimum clinically important differences}},
journal = {BMC medical research methodology},
year = {2021},
doi = {10.1186/s12874-021-01228-7},
pmid = {33637039},
url = {https://doi.org/10.1186/s12874-021-01228-7}
}
Studies this one cites
Referenced by this study and also in the alzhub library, so you can read them here.