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Variance formulae for multiphase stepped wedge cluster randomized trial.

Pengyue Zhang1, Abigail Shoben2, Rebecca Jackson3

  • 1Department of Biomedical Informatics, Ohio State University, Columbus, Ohio, USA.

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|August 19, 2020
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Summary
This summary is machine-generated.

Multiphase stepped wedge cluster randomized trials (MSW-CRT) allow evaluating multiple interventions sequentially. Analyzing all study data enhances statistical power compared to intervention-specific analyses.

Keywords:
cluster-period mean autocorrelationlinear mixed modelmultiple interventionsseparate analysisstepped wedge design

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Area of Science:

  • Biostatistics
  • Clinical Trials Methodology
  • Epidemiology

Background:

  • Multiphase stepped wedge cluster randomized trials (MSW-CRT) are complex designs for evaluating multiple interventions sequentially.
  • While proposed, the statistical properties of MSW-CRT designs have not been thoroughly investigated.

Purpose of the Study:

  • To derive closed-form variance formulae for testing intervention effects in MSW-CRT.
  • To provide relationships between variances, design parameters, and statistical power.
  • To evaluate the impact of different analytical approaches on study power.

Main Methods:

  • Derivation of closed-form variance formulae for MSW-CRT.
  • Analysis of relationships between variance, sample size, power, and design parameters (e.g., autocorrelation, lag).
  • Illustrative examples to demonstrate power calculations and comparisons.

Main Results:

  • Identified conditions where variances for different intervention effects may be similar.
  • Described the impact of cluster-period autocorrelation and intervention lag on variance.
  • Demonstrated that using all study data yields higher power than intervention-specific analyses (relative power loss <15%).
  • Showed that decreasing total periods and lag simultaneously reduces power (relative power loss <20%).

Conclusions:

  • The derived variance formulae facilitate sample size and power calculations for MSW-CRT.
  • Comprehensive data utilization in MSW-CRT is crucial for maintaining statistical power.
  • Understanding design parameter effects is essential for optimizing MSW-CRT efficiency.