Cluster randomized trials of individual-level interventions were at high risk of bias

•Due to the risks of identification and recruitment bias, opting for a cluster design when individual randomization would be feasible needs a strong justification. Concerns around contamination are unlikely to be acceptable justifications; although estimation of indirect effects might be.•When cluster randomization is adopted, we recommend that authors provide a clear justification for the choice of cluster randomization and clearly outline strategies to mitigate increased risks of bias. This should include identification and recruitment by someone blind to the treatment allocation and minimal or objective individual-level eligibility criteria.•Other good conduct procedures which are routinely implemented in individually randomized trials should be followed. These include implementation of the randomization using an accepted method of allocation concealment, for example, by using an independent statistician to generate the allocation sequence; blind outcome assessment when outcomes are subjective; and clear pre-specification (in a protocol or trial registration site) of the primary outcome including primary assessment time and method of primary analysis.•All these aspects should be clearly reported as per CONSORT guidelines. To ensure particular clarity around identification and recruitment, authors should also provide a timeline-cluster diagram.