Table 2.

Progression criteria from feasibility trial to full randomised controlled trial

Progression criterion	Method of assessment
1. Is the intervention feasible to deliver and acceptable to participants and their helpers?	USE questionnaire Participant/helper interviews
2. Are participants willing to be randomised to the intervention?	Recruitment experiences of the study team and fieldworkers Insight from qualitative interviews with participants
3. Are appropriate and effective routes of recruitment available to achieve a powered sample size in a full trial?	Coming close to the sample size, as judged by the Trial Steering Committee (TSC), with reasonable expectations of being able to address any recruitment issues
4. Are identified barriers and challenges to implementation of the intervention planned for and surmountable?	Process evaluation which will present a SWOT analysis (Strengths, Weaknesses, Opportunities and Threats) and action plan
5. Are appropriate retention rates achieved at 12-month follow-up?	Measured using the following scale in both the intervention and control group at 12 months: if>70% followed up, proceed; if 50%–69% followed up, discuss with TSC; if<49% followed up, do not proceed
6. Do the majority (>50%) of participants within the intervention group visit the app at least twice or do 25% of participants randomised use it three or more times?	App usage statistics and/or participant interviews
7. Do the data collection procedures effectively collect the data required for a full trial? Successful completion of at least one data collection method (BMI, physical activity or healthy eating) at both baseline and at 12 months in those retained measured using the following scale:	If>90% of at least one data collection measure completed, proceed If 70%–89% of at least one data collection measure completed, discuss strategies for improvement in future trial with TSC If<70% of all three data collection measures completed, do not proceed without further modification and pilot
8. Are the intervention costs of a full trial covered?	Identification of a source to pay access and treatment costs