Table 4 CREST feasibility outcomes and the criteria for progressing to a future definitive randomised controlled trial

1

Number of participants (people with dementia and caregivers) who are screened, judged eligible and agree to take part in the study

30% of eligible participants (people with dementia & caregivers) can be recruited

2

Identification of optimal strategy for recruitment of participants for future definitive trial

Optimal recruitment strategy identified, informed by recruitment rates and qualitative data from key stakeholders

3

Identification of barriers and enablers to stigma change in dementia

A list of barriers and enablers to stigma change in dementia generated from the collection and analysis of the qualitative data from key stakeholders

4

Willingness of key gatekeepers (i.e., GPs, local Alzheimer Cafés, Western Alzheimer groups) to recruit participants

> 60% of key gatekeepers approached willing to support the recruitment of participants

5

Feasibility and acceptability of the intervention content, delivery and fidelity assessments

> 70% of participants attend ≥ 60% of intervention sessions. The intervention can be delivered in line with feasibility and fidelity targets (i.e. the content, frequency, and quality of the programmes are delivered in line with the programme manuals)

6

Follow-up rates, outcome completion and adherence or compliance rates

< 20% of participants lost to follow-up;

≥ 50% of people with dementia and caregivers adhere to the intervention

7

Reasons for non-recruitment, non-adherence or attrition

A list of the reasons for non-recruitment non-adherence or attrition generated from the qualitative data obtained from participants

8

Acceptability of the recruitment process, assessments, data collection tools, intervention content and delivery to participants

Recruitment processes, assessment, data collection tools, intervention content and delivery perceived as acceptable by > 70% of participants (people with dementia and caregivers)

9

Baseline score and variability of secondary outcome measures among participants to inform sample size estimates for a future definitive trial

Sample size estimates for required number of persons with dementia can be calculated, from baseline scores on the primary outcome measure of quality-of-life in people with Alzheimer’s disease (the QoL-AD). Variability of secondary outcomes to fall within acceptable parameters, when calculating sample size and possible attrition

10

Evaluation of cost analyses process

Economic data can be collected to inform the design of the economic component of any future trial.