Table 4 Specified factors that inform assessment of trial feasibility in addition to, or instead of, progression criteria

(n=33)

 Qualitative data

12 (36%)

  Process evaluation

5 (15%)

  Participant feedback^b

3 (9%)

  Qualitative interview data

3 (9%)

  Qualitative data about implementation

1 (3%)

 Trial design

6 (18%)

  Outcome measures

3 (9%)

  Data collection

1 (3%)

  Performance of trial pathways

1 (3%)

  Protocol adherence

1 (3%)

  Selection bias

1 (3%)

 Recruitment

5 (15%)

  Recruitment processes and ability to recruit

4 (12%)

  Difficulty with screening

1 (3%)

 Contextual challenges

4 (12%)

  COVID-19

2 (6%)

  Healthcare context

2 (6%)

  Changing policy

1 (3%)

 Implementation of the trial

3 (9%)

  Resources required

2 (6%)

  Enthusiasm of researchers

1 (3%)

  Number of recruiting sites needed

1 (3%)

 Funding considerations

3 (9%)

 Indication of efficacy or effectiveness

3 (9%)

 Interest, acceptability or uptake of intervention

3 (9%)

 Expectations of collaborators

1 (3%)

 Retention or attrition

1 (3%)

(n=32)

 Qualitative data

17 (53%)

  Acceptability to participants^b

11 (34%)

  Participant feedback^b

3 (9%)

  Qualitative data about implementation

3 (9%)

  Qualitative interview data

2 (6%)

  Acceptability to healthcare providers^b

2 (6%)

  Process evaluation

1 (3%)

 Recruitment

14 (44%)

  Recruitment rate

11 (34%)

  Recruitment processes

2 (6%)

  Consent rate

1 (3%)

  Recruitment time

1 (3%)

 Indication of efficacy or effectiveness

10 (31%)

 Trial design

10 (31%)

  Sample size required for the definitive RCT

5 (16%)

  Data collection

3 (9%)

  Ability to do internal pilot as part of future def RCT

1 (3%)

  Need to further development the intervention (not possible in an RCT)

1 (3%)

 Retention or attrition

9 (28%)

 Interest, acceptability or uptake of intervention

9 (28%)

  Intervention adherence or engagement

5 (16%)

  Completion or withdrawal rates

3 (9%)

  Willingness to be randomised

1 (3%)

 Implementation of the intervention

7 (22%)

  Intervention delivery

3 (9%)

  Intervention fidelity

2 (6%)

  Intervention feasibility

1 (3%)

  Complexity of the intervention

1 (3%)

 Implementation of the trial

4 (13%)

  Acceptability or willingness of healthcare professionals

2 (6%)

  Patient acceptability of study procedures

1 (3%)

  Resources required

1 (3%)

 Safety or adverse events

3 (9%)

 Contextual challenges

1 (3%)

  Healthcare context

1 (3%)

 Funding considerations

1 (3%)