The “best balance” allocation led to optimal balance in cluster-controlled trials

Abstract Objective Balance of prognostic factors between treatment groups is desirable because it improves the accuracy, precision, and credibility of the results. In cluster-controlled trials, imbalance can easily occur by chance when the number of cluster is small. If all clusters are known at the...

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Bibliographic Details
Published in:Journal of clinical epidemiology 2012-02, Vol.65 (2), p.132-137
Main Authors: de Hoop, Esther, Teerenstra, Steven, van Gaal, Betsie G.I, Moerbeek, Mirjam, Borm, George F
Format: Article
Language:English
Subjects:
Biological and medical sciences
Clinical trial. Drug monitoring
Clinical trials
Cluster Analysis
Cluster randomized trial
Epidemiologic Research Design
Epidemiology
General pharmacology
Humans
Imbalance
Internal Medicine
Matching
Medical sciences
Medicine
Methods
Minimization
Pharmacology. Drug treatments
Prognosis
Prognostic factors
Random Allocation
Randomization
Randomized Controlled Trials as Topic
Stratification
Studies
Therapy
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Summary:Abstract Objective Balance of prognostic factors between treatment groups is desirable because it improves the accuracy, precision, and credibility of the results. In cluster-controlled trials, imbalance can easily occur by chance when the number of cluster is small. If all clusters are known at the start of the study, the “best balance” allocation method (BB) can be used to obtain optimal balance. This method will be compared with other allocation methods. Study Design and Setting We carried out a simulation study to compare the balance obtained with BB, minimization, unrestricted randomization, and matching for four to 20 clusters and one to five categorical prognostic factors at cluster level. Results BB resulted in a better balance than randomization in 13–100% of the situations, in 0–61% for minimization, and in 0–88% for matching. The superior performance of BB increased as the number of clusters and/or the number of factors increased. Conclusion BB results in a better balance of prognostic factors than randomization, minimization, stratification, and matching in most situations. Furthermore, BB cannot result in a worse balance of prognostic factors than the other methods.
ISSN:0895-4356
1878-5921
DOI:10.1016/j.jclinepi.2011.05.006