Reporting of cluster randomised crossover trials: extension of the CONSORT 2010 statement with explanation and elaboration.

This article presents the CONSORT (consolidated standards of reporting trials) extension for cluster randomised crossover trials. A cluster randomised crossover trial involves randomisation of groups of individuals (known as clusters) to different sequences of interventions over time. The design has gained popularity in settings where cluster randomisation is required because it can largely overcome the loss in power due to clustering in parallel cluster trials. However, the design has many methodological complexities, requiring tailored reporting guidance. The guideline was developed using a survey and in-person consensus meeting, informed by a systematic review examining the quality of reporting in cluster randomised crossover trials and relevant CONSORT statements for individual, crossover, cluster, and stepped wedge designs. This article also provides recommended reporting items, along with explanations and examples.