Systematic review of ethics committee approval and participant information and consent in reports of cluster randomized trials – author survey of handling participant information and consent.

Data are number (%).

An ethics committee approval was considered obtained any time the corresponding author specified having difficulties or not in obtaining its approval.

Information was considered as partial when (i) the study hypothesis was not specified or (ii) the nature of the control group and experimental group was not specified or (iii) the arm to which the participant would be allocated to was not specified (only for trials for which randomization of clusters took place before inclusion of participant).

Participant inclusion was declared after cluster randomization in 66 trials. The corresponding authors of 53 of those reports answered this question.