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Barnes Maze Testing Strategies with Small and Large Rodent Models
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Group sequential designs for stepped-wedge cluster randomised trials.

Michael J Grayling1, James Ms Wason1, Adrian P Mander1

  • 1MRC Biostatistics Unit Hub for Trials Methodology Research, Cambridge Institute of Public Health, Cambridge, UK.

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|June 28, 2017
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Summary
This summary is machine-generated.

Interim analyses in stepped-wedge cluster randomised trials can reduce sample size by up to 31% without compromising error rates. This adaptation of group sequential methods enhances trial efficiency and ethical considerations for stepped-wedge designs.

Keywords:
Stepped wedgecluster randomised trialerror spendinggroup sequentialinterim analyses

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Area of Science:

  • Clinical Trials Methodology
  • Biostatistics
  • Epidemiology

Background:

  • Stepped-wedge cluster randomised trials (SW-CRTs) are increasingly used.
  • Existing SW-CRT designs lack guidance on incorporating interim analyses.
  • Group sequential methods offer efficiency and ethical benefits in individually randomised trials.

Purpose of the Study:

  • To adapt established group sequential methodology for SW-CRTs with interim analyses.
  • To provide guidance on designing SW-CRTs that allow for early stopping.
  • To evaluate the performance of SW-CRTs with interim analyses.

Main Methods:

  • Utilised the error spending approach for group sequential design.
  • Detailed assumptions for SW-CRTs with interim analyses.
  • Applied methods to a linear mixed model and a completed SW-CRT.
  • Explored quantile substitution for unknown variance.

Main Results:

  • Incorporating early stopping reduced expected sample size by up to 31% (null) and 22% (alternative).
  • Type-I and type-II error rates were maintained.
  • Restricted error maximum likelihood estimation was crucial for Type-I error control.

Conclusions:

  • Interim analyses in SW-CRTs can prevent prolonged trials of ineffective treatments.
  • Early stopping can expedite the implementation of effective treatments.
  • Trialists should consider incorporating early stopping into SW-CRT designs.