Cited by 97Statistical Methods in Clinical TrialsAdvanced Causal Inference TechniquesOptimal Experimental Design Methods

Minimization–reducing predictability for multi-centre trials whilst retaining balance within centre

Brown, Sarah, Thorpe, Helen, Hawkins, Kim, Brown, Julia·2005·Statistics in Medicine

Abstract

Minimization is often used to assign patients to treatment groups to ensure good balance in patient numbers within centre and other prognostic factors. Balance within centre is preferable since large imbalances between treatment arms may have logistical implications for centres, such as cost and resource implications. However, recent concern over high predictability of treatment allocation by centres when using minimization has caused this method to be questioned. We used data from current clinical trials to assess predictability and summarize subsequent within-centre imbalances with the aim of finding the most effective minimization method for reducing predictability whilst still retaining sufficient balance within centre, when randomization is to one of two treatments. We compared prediction rates and imbalances for deterministic minimization, and minimization incorporating various random elements, p (p=0.95,0.90,0.80,0.75,0.70). We also compared prediction rates and imbalance when centre was and was not included as a stratification factor. Incorporating a random element proved successful in reducing prediction rates whilst minimizing the inevitable increase in within-centre imbalance, whereas excluding centre as a stratification factor incurred major within-centre imbalance. We therefore suggest that minimization can still be used, and that centre can be included as a stratification factor, but a random element has to be incorporated into the minimization algorithm. Minimization incorporating a random element of 0.80 is the most efficient method to use based upon the simulations undertaken in this study of real clinical trial data using different probabilities of allocation.

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Crossref · 10.1002/sim.2391

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Authors
Brown, S., Thorpe, H., Hawkins, K., & Brown, J.
Affiliations
University of Leeds (GB)
Corresponding author
Brown, Sarah
Venue
Statistics in Medicine
Publisher
Wiley
Published
2005-11-30
Volume
24
Issue
24
Pages
3715-3727
ISSN
  • 0277-6715 (ISSN-L)
  • 1097-0258
OpenAlex
W2098974730
Cited by
97
References
8
Citations by year
2026: 3 · 2025: 2 · 2024: 10 · 2023: 6 · 2022: 2 · 2021: 9 · 2020: 4 · 2019: 4 · 2018: 7 · 2017: 7 · 2016: 6 · 2015: 8 · 2014: 7 · 2013: 4 · 2012: 5
FWCI
2.76
Type
journal article
Language
en
Open access
closed
Locations
  • Statistics in Medicine (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
  • Social Sciences › Decision Sciences › Management Science and Operations Research › Optimal Experimental Design Methods
Keywords
minimization, treatment allocation, predictability, multi-centre trials, randomization, stratification
MeSH terms
Algorithms, United Kingdom, Humans, Random Allocation, Models, Statistical, Multicenter Studies as Topic, Patient Selection

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