Table 3 Summary of progression criteria for study procedures

1. Feasibility to recruit and retain sufficient participants to meet targets within timeframe

Recruitment: percentage of eligible patients recruited; if > 30% recruited = proceed, if < 10% = unlikely to be feasible; if 10–30% = CI to consider feasibility of proceeding based on screening rate and possible steps to increase recruitment.

Retention: percentage of participants retained; if > 80% = proceed, if < 60% = unlikely to be feasible, if 60–80% = CI to consider feasibility of proceeding based on available data and possible steps to increase retention.

Recruitment: 45 were eligible (96 were screened); 16% of eligible patients (7% of those screened) were recruited. CI decision was ‘unlikely to be feasible’ based on lower than anticipated screening rate.

Retention: 71% of participants starting the intervention were retained. CI decision was ‘unlikely to be feasible’ based on lower than anticipated screening and recruitment rates.

2. Intervention adherence

Based on a hypothesised minimum dose; if > 80% = proceed, if < 70% = unlikely to be feasible, if 70–80% = CI to consider feasibility of proceeding based on available data.

Adherence was 72% (76 out of a possible 105 sessions completed) for all participants. Based on the 5 participants that did not drop-out, adherence was 97% (73 out of 75 sessions completed). CI decision was ‘proceed’ based on available data from participants that completed the study.

3. Intervention is acceptable to participants

Intervention acceptability was considered by measuring FS, RPE, and EES responses. Aggregate values for proceed were as follows: FS = > 0, RPE < 15; EES = > 3. Values below these thresholds = CI to consider feasibility of proceeding based on magnitude of values.

Acceptability of the intervention was good (see Table 2). Decision was ‘proceed’.

4. Randomisation processes acceptable to recruited participants

> 50% of recruited participants report agree about the acceptability of randomisation processes; the CI will apply discretion in judging whether this criterion has been met via discussion with participants.

Although planned, randomisation was not applied due to low recruitment. Control arm of the trial was abandoned.

5. Outcome measures acceptable to participants

Percentages of participants reporting acceptability of outcome measures on self-report questions. If > 80% = proceed, if < 50% = unlikely to be feasible, if 50–80% = CI to consider feasibility of proceeding based on available data and possible steps to increase acceptability.

Five out of 5 participants (100%) who completed the intervention recorded all measures and self-reported them to be acceptable. Decision was ‘proceed’.