Journal article

When should matching be used in the design of cluster randomized trials?

Patty Chondros, Obioha C Ukoumunne, Jane M Gunn, John B Carlin



For cluster randomized trials (CRTs) with a small number of clusters, the matched-pair (MP) design, where clusters are paired before randomizing one to each trial arm, is often recommended to minimize imbalance on known prognostic factors, add face-validity to the study, and increase efficiency, provided the analysis recognizes the matching. Little evidence exists to guide decisions on when to use matching. We used simulation to compare the efficiency of the MP design with the stratified and simple designs, based on the mean confidence interval width of the estimated intervention effect. Matched and unmatched analyses were used for the MP design; a stratified analysis was used for the strati..

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Funding Acknowledgements

Patty Chondros was supported by the Australian National Health and Medical Research Council Public Health Postgraduate Scholarship. Obi Ukoumunne was supported by the National Institute for Health Research Applied Research Collaboration South West Peninsula. The views expressed in this publication are those of the authors and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care.