Table 3 Concerns and recommendations for informing the design and delivery of a definitive RCT

Motivation for taking part

Recruiting staff to recognise that not all people are motivated by altruism

Endorsement by stakeholders (clinicians and funders)

Required for identifying potential participants and starting the recruitment process; training for Participant Identification Centre (PIC) clinicians to be aware of their “gate-keeping” role

Desperation for improvement

PIC clinicians and recruiting researchers to ensure potential participants are informed and understand the need for equipoise through careful reiteration of the current state of knowledge and potential risks as well as benefits of participation with the aim to facilitate appropriate decision-making

Abandoned to the control group

Consider more active forms of comparator, or waiting list control. Careful inclusion of interviews to ascertain group preference

Negative effects on mental health (if allocated to the control)

PIC clinicians and recruiting researchers to be aware of the vulnerability of potential participants; more active monitoring of adverse events in the control group, ensure mental health deterioration included in monitoring and reporting of adverse events

Compensatory behaviour change (control group participants seek their own version of the intervention)

Consider more active comparator or waiting list control; better monitoring of control group activity. Consider alternative trial designs such as rigorous pragmatic or observational cohort studies.

Recommend process evaluations always include control group participants and update reporting check lists to this effect