International journal of stroke : official journal of the International Stroke Society
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Review
Illustrating problems faced by stroke researchers: a review of cluster-randomized controlled trials.
The cluster-randomized controlled trial is a design increasingly used in prevention and health care evaluation studies and is highly relevant to stroke research. However, there are methodological issues that make it complex to implement. These are not always fully appreciated, with reviews continuing to reveal deficiencies. ⋯ Several trials appeared underpowered because of problems in determining an appropriate sample size, defining appropriate clusters, and recruiting and retaining clusters and patients. Cluster-randomized controlled trials are difficult to design and perform due to the combination of methodological and practical difficulties. It is important that further improvements are made to reporting cluster-randomized trials and intraclass correlation coefficients should be estimated using a standardized approach and reported consistently; this would be beneficial for stroke researchers when designing future cluster-randomized trials.