This research project is in progress. PCORI will post the research findings on this page within 90 days after the results are final.
What is the research about?
One way to see if a new treatment works is to compare it with a standard treatment already known to work. However, giving some people the treatment that works and others a treatment that may not work may pose an ethical dilemma. The stepped-wedge study design can help solve this issue. In stepped-wedge designs, all groups get the standard treatment. Then, at predefined times, called steps, the research team assigns groups by chance to begin the new treatment or continue taking the standard treatment. By the end of the study, all groups have received both the new and standard treatments. Stepped-wedge studies let researchers compare groups getting the new and standard treatments at each step. These studies also allow researchers to compare people over time, before and after they switch to the new treatment.
Most stepped wedge methods don’t apply to cohort studies, which are useful for following people over time. Also, most stepped-wedge methods assume that data collection will go smoothly. For example, the methods don’t plan for missing data or differences in study group size. However, data collection rarely goes perfectly.
In this study, the research team is developing and testing methods to improve the design and analysis of stepped-wedge studies that enroll people in different ways, with different types of outcomes and missing data patterns.
Who can this research help?
Results may help researchers conduct more rigorous studies using the stepped-wedge design.
What is the research team doing?
The research team is developing methods for conducting stepped-wedge trials. They are working with clinicians to prioritize concerns and problems with this type of trial. The team is developing
- A guide for conducting stepped-wedge studies
- Methods that researchers can use when there are missing data or when groups vary in size
- Software to help researchers review data after each step, which can help them know if they can or should stop a study early
The team is testing the new methods with two existing studies. One study is on colorectal cancer screening. The other is on the care of patients who have three conditions at once: high blood pressure, diabetes, and kidney disease.
Research methods at a glance
|Goal||To develop methods for conducting stepped-wedge trials that accommodate open and closed cohort and cross-sectional designs and account for data collected in real-world clinical settings|
The research team is using statistical methods and simulation strategies to develop methods for the stepped-wedge design that accommodate