Table 2 Feasibility assessment

Feasibility of the study

Interviews (i.e. post-trial feasibility interviews)—e.g. acceptability of randomisation; recommended changes to procedures

Framework analysis (structured, purposive coding of qualitative content)

Formative (included to support design of a definitive trial, but no assigned progression criteria cut-offs)

Acceptability of intervention

Drop-out rate (and reasons for withdrawal)

Frequencies/percentages

≥80% of SMART group complete ≥6 sessions (green), 79-60% complete ≥6 sessions (amber), <60% complete ≥6 sessions (red)

Intervention progression and completion rates

Descriptive statistics/average percentage completion (and range)

Formative

Interviews

Framework analysis

Formative

Credibility of intervention

Interviews (plus relevant comments within session recordings)

Framework analysis

Formative

Feasibility of measures

Missing response-data

Percentage

Formative

Estimates of completion time

Descriptive statistics

Formative

Late completion

Percentage

Formative

Interviews

Framework analysis

Formative

Feasibility of framework for cost-effectiveness analysis

Missing data on intervention resource use

Percentage

Formative

Missing response data—QALY measures and service and resource use questionnaire

Percentage

Formative

Estimates of time taken to complete measures - QALY measures and service and resource use questionnaire

Descriptive statistics

Formative

Feasibility of framework for cost-effectiveness analysis (cont…)

Late completion of measures—QALY measures and service and resource use questionnaire

Percentage

Formative

Feasibility of recruitment and randomisation

Numbers of outpatients eligible

Frequencies/percentages

Formative

Numbers eligible who expressed interest/discussed w/researcher

Frequencies/percentages

Formative

Numbers consenting/randomised

Frequencies/percentages

≥80% of planned (green), 79–60% of planned (amber), <60% of planned (red)

Reasons for non-participation? (e.g. online modality as barrier? Unwilling to be randomised?)

Frequencies/percentages

Formative

Interviews

Framework analysis

Formative

Feasibility of retention within the study

Number completing baseline and outcome assessments at Follow-up 1 (3 months)

Frequencies/percentages

≥80% completing to follow-up 1 (green), 79–-60% completing (amber), <60% completing (red)

Signal of efficacy

Indicative estimation of intervention effects

Estimates of (group-level) effect sizes with 95% CIs and proportions achieving reliable/clinically significant change

Red: 95% CIs exclude the possibility of a meaningful effect size for our screening measures (based on reliable-change criteria)