Fig. 2

Trial profile showing school and child recruitment and retention. N refers to the number of schools (clusters) and n refers to the number of children (individual participants). Two schools that had been allocated to cohort 2 withdrew whilst waiting to commence the trial and so were subsequently replaced with two of the four schools on the waiting list, prior to cohort 2 commencing. All schools that started the trial remained within the trial and so all the randomised clusters are present at baseline and at each follow-up point. The percentage in brackets for the proportion of children with data at both baseline and follow up is calculated from the total number of recruited children in the schools at baseline. Not all children with a follow-up measure necessarily had a corresponding baseline measure (or vice versa) due to different children being absent on the day of the main and additional assessments for each of the time points, and/or due to children leaving or moving between schools. In all the analyses, children were analysed in the group (intervention or control) to which the school they were enrolled in at baseline was randomized