Table 1 Summary of continuation criteria
aContinuation criteria | Measures used | Assessment of whether criteria have been met |
|---|---|---|
Feasibility to recruit and retain practices. | • Number of practices responding to a call for Expression of Interestb • Practice retention rates | If > 50 general practices within 2 months respond to call, then it is likely to proceed to full trial (green). If < 40 practices respond to call, then progression is unlikely to be feasible (red). If 40–50 practices respond within 2 month, then the Trial Steering Committee (TSC) will consider the feasibility of proceeding to the full-scale trial (amber) based on taking steps to improve response rate. If 8 practices are retained throughout a 6-month intervention period, then it is likely to proceed (green). If < 5 practices are retained, then a full-scale trial is unlikely to be feasible (red). If 5–7 practices are retained throughout the intervention period, then the TSC will consider feasibility of proceeding (amber) based on taking steps to improve retention. |
Intervention is implemented as planned; that is, audit and feedback, addition of electronic prompts and delivery of a reminder in any format and receipt of intervention by eligible population of people with diabetes in participating practices | • Exploration of implementation fidelity during practice staff and patient interviews • Practice self-report during research support phone calls • Percentage of eligible patients receiving intervention based on practice audit data | If all core intervention components (audit, prompts, reminders) have been delivered by > 75% of practices, then it is likely to proceed to full trial (green) subject to review of qualitative data. If < 50% have delivered components, then it is unlikely to proceed (red). If 50–75% have delivered core components, then the TSC will consider the feasibility of proceeding (amber). The TSC will consider both the quantitative and qualitative data to judge whether the intervention is has been implemented. |
Intervention is acceptable to patients and practice staff | • Percentages of staff reporting acceptability of intervention on self-report questionnaire. • Issues regarding acceptability of the intervention explored in qualitative interviews with staff and patients | If the intervention is acceptable to > 75% practice staff, then it is likely to proceed to full trial subject to review of qualitative data (green). If intervention is acceptable to < 50% staff, then it is unlikely to proceed (red). If the intervention is acceptable to 50–75% staff, then TSC will consider feasibility of proceeding (amber). The TSC will consider the quantitative and qualitative data and make an overall judgement on whether the intervention is acceptable. |
Intervention has potential effect on screening uptake and demonstrates potential cost savings which are likely to outweigh the direct cost of implementing the intervention; specifically, the intervention (1) increases the absolute number of patients registered for diabetic retinopathy screening and (2) increases the absolute number of patients attending or intending to attend screening, measured descriptively | • Number registered for diabetic retinopathy screening based on practice audit data • Number attending or intending to attend based on practice audit data • Potential savings calculated based on cost of delivering intervention compared to control, and absolute increases in number attending or intending to attend | The TSC will judge whether the intervention has some positive impact and demonstrates cost savings. |