Table 4 Assessment of feasibility stop-go criteria

Stop criteria: Less than 70 children and adolescents have been recruited (∼ 70% of the target) and if the qualitative data collected suggest that recruitment cannot be improved any further.

80 participants were recruited to the study.

Go

Stop criteria: The 6-month follow-up is < 80% and if the qualitative data suggest that follow-up rates cannot be improved any further.

91.% (32) of participants completed their 6-month primary outcome measures

Go

Stop criteria: Data suggest the interventions are not acceptable to children and/or their parents.

All participants started the treatment that they were allocated. Three out of the 40 participants in the activity management arm (7.5%) and three out of the 40 participants in the GET arm (7.5%) discontinued treatment early (defined as discontinuing treatment within 6 months of randomisation).

Qualitative feedback supports the acceptability overall of both intervention arms.

Go,

Amendments:

1. Treatment sessions could be carried out via Skype.

2. Fitbits only offered routinely to younger children and those unable to manually measure their heart rate (subject to availability).

Stop criteria: If the Data and Safety Monitoring Committee (DSMC) and the Trial Steering Committee (TSC) recommend the trial is stopped for safety reasons.

The TSC, DSMC and TMG concluded that the trial methodology and interventions were acceptable and feasible, that no significant changes needed to be made to either the interventions or outcomes and that recruitment should continue seamlessly to the full trial. As participants have consented to the use of data in the full trial, and neither the interventions nor outcomes had changed; the decision was made (with the support of the DSMC, TSC and TMG) to use the outcome data collected during the feasibility RCT in the full trial.

Go