What is a stepped-wedge cluster design?

The stepped wedge cluster randomised trial is a novel research study design that is increasingly being used in the evaluation of service delivery type interventions. The design involves random and sequential crossover of clusters from control to intervention until all clusters are exposed.

What is a stepped-wedge cluster randomized trial?

Abstract. The stepped-wedge cluster randomized trial (SW-CRT) involves the sequential transition of clusters (such as hospitals, public health units or communities) from control to intervention conditions in a randomized order. The use of the SW-CRT is growing rapidly.

What is a non randomized stepped-wedge design?

In NR-DD designs, all units start out untreated and are followed for a fixed number of visits; then, non-randomly chosen units are switched to the new policy or intervention and compared to controls continuing to be untreated. However, non-randomized stepped-wedge (NR-SW) designs have recently attracted researchers.

What is a cluster design?

Cluster randomised trials (CRTs) involve randomisation of groups (clusters) of individuals to control or intervention conditions.1 The CRT design is commonly used to evaluate non-drug interventions, such as policy and service delivery interventions.

How is the stepped wedge cluster randomised trial used?

The stepped wedge cluster randomised trial is a novel research study design that is increasingly being used in the evaluation of service delivery type interventions. The design involves random and sequential crossover of clusters from control to intervention until all clusters are exposed.

What is the design effect of stepped wedge?

Additionally, a design effect (used to inflate the sample size of an individually randomized trial to that required in a cluster trial) has been established, which has shown that the stepped wedge CRT could reduce the number of patients required in the trial compared to other designs.

What should be included in a step wedge study?

Comprehensive literature review of studies or protocols using a stepped wedge design. Data were extracted from the studies in three categories for subsequent consideration: study information (epidemiology, intervention, number of participants), reasons for using a stepped wedge design and methods of data analysis.

Which is better a parallel study or a stepped wedge trial?

When the clusters are relatively homogeneous (that is, the intra-cluster correlation is small), parallel studies tend to deliver better statistical performance than a stepped wedge trial.