Reporting of cluster randomised crossover trials 2023: extension of the CONSORT 2010 statement with explanation and elaboration

In this report we present the Consolidated Standards of Reporting Trials (CONSORT) extension for the cluster randomised crossover (CRXO) trial. A CRXO trial involves randomisation of groups of individuals (‘clusters’) to different sequences of treatments over time. The design has gained popularity in settings where cluster randomisation is required as 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 CRXO trials and relevant CONSORT statements for individual, crossover, cluster and stepped-wedge designs. We provide recommended reporting items, along with explanations and examples.