Stepped Wedge Cluster Randomized Trials: A Methodological Overview

Abstract

Background: Stepped wedge cluster randomized trials enable rigorous evaluations of health intervention programs in pragmatic settings. In the present study, we aimed to update neurosurgeon scientists on the design of stepped wedge randomized trials.

Methods: We have presented an overview of recent methodological developments for stepped wedge designs and included an update on the newer associated methodological tools to aid with future study designs.

Results: We defined the stepped wedge trial design and reviewed the indications for the design in depth. In addition, key considerations, including mainstream methods of analysis and sample size determination, were discussed.

Conclusions: Stepped wedge designs can be attractive for study intervention programs aiming to improve the delivery of patient care, especially when examining a small number of heterogeneous clusters.

Keywords: Cluster randomized trials; Intraclass correlation coefficient; Methodological review; Sample size determination; Statistical software; Stepped wedge design.

Figure 1.

A schematic of stepped wedge design for the Early Recognition and Response to Increases in Surgical Site Infection (Early 2RIS) Trial. The shaded cell indicates treatment status, and a white cell indicates control status. There are 12 randomization sequences (defined by the first time period during which each group of clusters crossover to intervention). There are in total 105 clusters and 13 time periods. In the Early 2RIS trial, the baseline period is one year, and each subsequent period is 3 months.