Table 2.

Progression criteria for the PolyPrime study

Criteria	Data source(s)	Progression criteria
		Stop (unless there are clear and modifiable contextual or design issues that account for thisa)	Amend	Go
GP practice recruitment	Recruitment records held by research nurse(s)	If ≤5 GP practices are recruited within 8 months	If 6–9 GP practices are recruited and/or it takes longer than predicted (6-8 months)	If ≥10 GP practices are recruited to take part in ≤ 6 months
GP practice retention	Retention records held by research nurse(s)	If ≤5 GP practices are retained for the required period	If 6-9 GP practices can be retained for the required period	If ≥10 GP practices can be retained for the required period
Patient recruitment	Recruitment records held by Research Fellow/Assistant	If ≤59 patients are recruited within 5 monthsb	If 60–95 patients are recruited within 5 monthsb	If ≥96 patients are recruited within 5 monthsb
Patient retention	Retention records held by Research Fellow/Assistant	If ≤49% of patients are retained for the required period	If 50–79% of patients are retained for the required period	If ≥80% of patients are retained for the required period
Completeness of outcome data	Data collected during the study (case report forms, questionnaires)	≤49% of each patient self-report and GP-reported outcome measure is complete	If 50-79% of each patient self-report and GP-reported outcome measure is complete	If ≥80% of each patient self-report and GP-reported outcome measure is complete

^aThis includes aspects of study and/or data collection procedures that may be modified in advance of a full-scale definitive cRCT

^bNote that if ethics amendments are made to study recruitment procedures during this time period, the 5-month recruitment period may be extended (up to 8 months’) to enable sufficient time to assess patient recruitment rates

^cBased on data collected from the 6 intervention arm GP practices