Table 2 CReDECI 2 [31] checklist for QRI-Two

1 Description of the intervention’s underlying theoretical basis

Theoretical basis of QRI-Two from two underlying theories:

a) RCTs are Complex Adaptive Systems and local sites and recruiters implement the RCT protocol with some freedom, necessitating understanding of contextual factors influencing behaviour [32]

b) QRI methods identify known ‘clear obstacles’ and unknown or underestimated ‘hidden challenges’ to recruitment that can be revealed and understood in phase I, and then addressed in phase II through targeted remedial actions [17]

3

2 Description of all intervention components, including the reasons for their selection as well as their aims / essential functions

QRI-Two phase I comprises: Analysis of RCT documents and accrual data to identify barriers to recruitment, especially hidden challenges revealed by QRI-analysis; plus workshop to present diagnosis of recruitment barriers and discuss remedial actions

9, 10

3 Illustration of any intended interactions between components

Workshop facilitates discussion of recruitment barriers in the context of the RCT team’s clinical knowledge and enrolment experiences

10

4 Description and consideration of the context’s characteristics

Each RCT’s documents and accrual data provide context. The QRI researcher draws on knowledge and experience of other QRIs

10

5 Description of the pilot test and its impact on the definitive intervention

Four RCTs confirmed the feasibility of undertaking the streamlined process of analysis rapidly and the value of the workshop discussion with the RCT team.

7

6 Description of the control (comparator) and reasons for the selection

Six RCTs at the start-up stage (control) were compared with RCTs underway with enrolment shortfalls. This clarified that the QRI-Two had greater relevance for actively-enrolling RCTs with accrual data.

7

7 Description of the strategy for delivering the intervention within the study context

QRI-Two is delivered by two QRI researchers. The analysis and workshop can be undertaken within 2-6 weeks of receipt of RCT documents and accrual data.

10

8 Description of all materials or tools used to deliver the intervention

RCT team need to supply RCT documents (protocol and patient-information materials) and all available accrual data. QRI researchers undertake analysis and present findings for discussion at workshop.

10

9 Description of fidelity of the delivery process compared with the study protocol

All RCTs provided the documents and accrual data as required. The QRI-Two analysis and workshop were delivered according to protocol in all cases.

7

10 Description of a process evaluation and its underlying theoretical basis

The feasibility of the QRI-Two was assessed in terms of undertaking the analysis and workshop rapidly, recruitment barriers identified, remedial actions proposed, QRI-informed training delivered, and feedback from RCT teams about the usefulness of the QRI-Two.

6, 7

11 Description of internal facilitators and barriers potentially influencing the delivery of the intervention

Scheduling the workshop and including the most appropriate members of the RCT team was sometimes difficult because of clinical or other commitments.

12 Description of external conditions or factors occurring during the study which might have influenced the delivery of the intervention or how it works

The variable quantity and quality of accrual data provided by the RCT teams meant a greater reliance on clues about the existence of recruitment barriers rather than evidence in some RCTs.

11

13 Description of costs or required resources for intervention delivery

QRI-Two analysis and workshop requires time-commitment of several days for senior researchers. The cost is a fee to cover this time, depending on scale and complexity of RCT.