Rollout trial designs in implementation research are often necessary and sometimes preferred

Area of Science:

• Health Services Research
• Clinical Trial Design
• Implementation Science

Background:

• Rollout designs, such as stepped wedge, involve staggered implementation of programs or services.
• Concerns exist about confounding effects in rollout designs, leading to recommendations for their limited use.
• However, rollout designs can be more suitable than parallel-group designs due to ethical, scientific, or practical considerations.

Purpose of the Study:

• To define and provide rationale for stepped wedge and other rollout trial designs.
• To illustrate the application of these designs with examples from recent trials.
• To summarize the advantages and drawbacks of rollout designs.

Main Methods:

• Investigating ethical, scientific, and practical reasons for employing rollout designs.
• Defining stepped wedge and broader rollout designs where all units eventually receive the intervention.
• Analyzing examples of completed and ongoing rollout trials.

Main Results:

• Staged implementation is ethically necessary when delaying an effective service is unacceptable.
• Stepped wedge designs offer increased statistical power compared to parallel-group designs.
• Rollout designs can accommodate comparisons across implementation phases and address logistical or community constraints.

Conclusions:

• Stepped wedge and rollout trial designs are effective for evaluating implementation strategies and policy changes.
• These designs are often necessary for practical, ethical, or scientific reasons in implementation trials.
• Understanding the specific advantages and disadvantages of rollout designs is crucial for appropriate application.