Table 1

Checklist of items to include when reporting a cluster randomised trial (adaptations from standard guidelines in italic)

Paper section and topicItemDescriptor
Title and abstract
Design1*How participants were allocated to interventions (eg random allocation, randomised, or randomly assigned), specifying that allocation was based on clusters
Background2*Scientific background and explanation of rationale, including the rationale for using a cluster design
Participants3*Eligibility criteria for participants and clusters and the settings and locations where the data were collected
Interventions4*Precise details of the interventions intended for each group, whether they pertain to the individual level, the cluster level, or both, and how and when they were actually administered
Objectives5*Specific objectives and hypotheses and whether they pertain to the individual level, the cluster level, or both
Outcomes6*Report clearly defined primary and secondary outcome measures, whether they pertain to the individual level, the cluster level, or both, and, when applicable, any methods used to enhance the quality of measurements (eg multiple observations, training of assessors)
Sample size7*How total sample size was determined (including method of calculation, number of clusters, cluster size, a coefficient of intracluster correlation (ICC or k), and an indication of its uncertainty) and, when applicable, explanation of any interim analyses and stopping rules
Sequence generation8*Method used to generate the random allocation sequence, including details of any restriction (eg blocking, stratification, matching)
Allocation concealment9*Method used to implement the random allocation sequence, specifying that allocation was based on clusters rather than individuals and clarifying whether the sequence was concealed until interventions were assigned
Implementation10Who generated the allocation sequence, who enrolled participants, and who assigned participants to their groups
Blinding (masking)11Whether participants, those administering the interventions, and those assessing the outcomes were blinded to group assignment. If done, how the success of blinding was evaluated
Statistical methods12*Statistical methods used to compare groups for primary outcome(s) indicating how clustering was taken into account, methods for additional analyses, such as subgroup analyses and adjusted analyses
Participant flow13*Flow of clusters and individual participants through each stage (a diagram is strongly recommended). Specifically, for each group report the numbers of clusters and participants randomly assigned, receiving intended treatment, completing the study protocol, and analysed for the primary outcome. Describe protocol deviations from study as planned, together with reasons
Recruitment14Dates defining the periods of recruitment and follow up
Baseline data15*Baseline information for each group for the individual and cluster levels as applicable
Numbers analysed16*Number of clusters and participants (denominator) in each group included in each analysis and whether the analysis was by intention to treat. State the results in absolute numbers when feasible (eg 10/20 not 50%)
Outcomes and estimation17*For each primary and secondary outcome, a summary of results for each group for the individual or cluster level as applicable, and the estimated effect size and its precision (eg 95% confidence interval) and a coefficient of intracluster correlation (ICC or k) for each primary outcome.
Ancillary analyses18Address multiplicity by reporting any other analyses performed, including subgroup analyses and adjusted analyses, indicating those prespecified and those exploratory
Adverse events19All important adverse events or side effects in each intervention group
Interpretation20Interpretation of the results, taking into account study hypotheses, sources of potential bias or imprecision and the dangers associated with multiplicity of analyses and outcomes.
Generalisability21*Generalisability (external validity) to individuals and/or clusters (as relevant) of the trial findings
Overall evidence22General interpretation of the results in the context of current evidence
  • * Addition to CONSORT guidelines 20012