Allocation concealment: a methodological review
Abstract
Rationale, aims and objectives: The accurate reporting of the trial methodology and results is essential for accurate judgement on the quality of the research. This review aims to assess the impact of the adequacy of allocation concealment on treatment effect estimates. Methods: A search was performed in MEDLINE (via the O vid platform) to identify all randomized controlled trials (RCTs) indexed in J anuary 2011 within its set of ‘core clinical journals’. Meta‐regression was undertaken on a subset of two arm trials to quantify the association between adequacy of allocation concealment and effect size. Results: Adequate allocation concealment methods were used in 27% (n = 23) of included trials. There was insufficient information given in 68% (n = 58) of trials to make a judgement on allocation concealment. Meta‐regression showed that there was a trend, not statistically significant, towards a smaller effect size between adequacy of allocation concealment and effect sizes. Conclusion: This review highlighted that research needs to be reported to a higher standard and there are many trials reporting poor methods of allocation concealment within the small sample of trials included in this review.
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Without adequate allocation concealment, even random, unpredictable assignment sequences can be subverted.
“Without adequate allocation concealment, even random, unpredictable assignment sequences can be subverted.336 346 347 348”
From SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials (2025) · cites this paper as [347]
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SPIRIT 2025 explanation and elaboration: updated guideline for protocols of randomised trials
Hróbjartsson, A., Boutron, I., Hopewell, S., Moher, D., Schulz, K. F., Collins, G. S., Tunn, R., Aggarwal, R., Berkwits, M., Berlin, J. A., et al. (2025) · BMJ · doi:10.1136/bmj-2024-081660 · Cited by 171 · see citing works
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- Authors
- Clark, L., Schmidt, U., Tharmanathan, P., Adamson, J., Hewitt, C., & Torgerson, D.
- Affiliations
- University of York (GB)
- Corresponding author
- Clark, Laura
- Venue
- Journal of Evaluation in Clinical Practice
- Publisher
- Wiley
- Published
- 2013-05-07
- Volume
- 19
- Issue
- 4
- Pages
- 708-712
- ISSN
- 1356-1294 (ISSN-L)
- 1365-2753
- OpenAlex
- W2137913700
- Cited by
- 12
- References
- 36
- Citations by year
- 2026: 1 · 2025: 3 · 2021: 2 · 2018: 1 · 2017: 1 · 2016: 2 · 2015: 1
- FWCI
- 0.20
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Evaluation in Clinical Practice (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Keywords
- allocation concealment, randomization, randomized controlled trials, trial methodology reporting, treatment effect estimation, meta-regression, methodological quality, reporting guidelines
- MeSH terms
- Humans, Random Allocation, Research Design, Randomized Controlled Trials as Topic
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