Incomplete Stepped Wedge Designs: Methods for Study Planning and Analysis [Methods Study], United States, 2007-2023 (ICPSR 39743)

Version Date: Mar 23, 2026

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Principal Investigator(s):
John S. Preisser, University of North Carolina at Chapel Hill

https://doi.org/10.3886/ICPSR39743.v1

Version V1

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Summary

In a stepped-wedge cluster randomized trial, or SW-CRT, researchers compare new treatments to standard treatments in groups of patients, such as patients at different clinics, to look at the treatments' effectiveness. They assign groups by chance to switch from the standard to new treatment at different time points until all groups have received the new treatment. The different time points to switch treatments are called steps.

SW-CRTs take time and resources. If researchers know they can't collect data on all groups and all steps in a SW-CRT, they can plan to use an incomplete SW-CRT design. In incomplete SW-CRTs, researchers plan the study knowing that some clinics or steps will have missing data. But researchers need better guidance for planning incomplete SW-CRTs that still get accurate results.

Also, current methods for planning how many patients and groups should take part in SW-CRTs don't work well for large studies. They also don't work well with certain types of outcomes, like yes or no outcomes; outcomes that have counts, like number of hospital visits; or continuous outcomes, like a score from 0 to 100.

In this study, the research team developed and tested new methods to design and analyze SW-CRTs with different patterns of planned missing data, large data sets, and different types of outcomes.

Citation

Preisser, John S. Incomplete Stepped Wedge Designs: Methods for Study Planning and Analysis [Methods Study], United States, 2007-2023. Inter-university Consortium for Political and Social Research [distributor], 2026-03-23. https://doi.org/10.3886/ICPSR39743.v1

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Funding

Patient-Centered Outcomes Research Institute (PCORI) (ME-2019C1-16196)

Subject Terms

Geographic Coverage

Distributor(s)

Inter-university Consortium for Political and Social Research
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Time Period(s)

2007 -- 2023
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Study Purpose

To develop and evaluate new statistical methods and procedures for designing and analyzing SW-CRTs with planned missed data, large data sets, and binomial, count, or continuous outcomes

Study Design

The research team developed trial planning and analysis methods based on a generalized estimating equation (GEE). They first developed IC to determine which data elements, such as cluster, period, or cluster-period, contribute the least amount of information to the treatment effect estimation. IC helps researchers identify efficient incomplete SW-CRT designs. The team applied the new method to data from the Expedited Partner Therapy study to calculate IC across different scenarios. For each scenario, the team omitted different data elements for different outcome types.

Next, the research team adapted a GEE method for calculating statistical power for SW-CRTs. They used the fast GEE power method to compute power in six different SW-CRT designs, including the Connect-Home study, for binary, count, and continuous outcomes.

The research team developed a new formula to assess the influence of data from a cluster-period on estimated treatment effects in GEE analysis of SW-CRTs. Also, the team developed a GEE method for cluster period-level data to quickly analyze aggregate data from large numbers of patient records. The team developed software programs for these methods.

Data Source

"Complete SW-CRT data from the Expedited Partner Therapy study: women ages 14-25 with chlamydia or gonorrhea in 24 local health jurisdictions in Washington State from 2007 to 2009 Incomplete SW-CRT data from the Connect-Home study: rehabilitation patients transitioning from skilled nursing facilities to home care from 2018 to 2022

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Original Release Date

2026-03-23

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Notes

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