Table 3 Selected quotations illustrating the themes developed from interviewees’ descriptions of DCT participant engagement activities

  Relatability of study aims

“The recruitment rate was so high. So, we got an astounding response rate to a cold call letter…And it’s because of the subject, it's because it’s retinopathy, blindness is the number one fear of people with diabetes and these are people that have been told they’ve got changes to their eyes and there’s nothing we can do about it…And that must be terrifying.” Case study interviewee 0049 Trial Staff (clinical/research)

“We also put quite a lot of work into our websites ahead of time and we’ve got a video on the front page from Fred McCauley who I knew used to be on BBC Scotland for years and I know he’s still doing the tour as a comedian.” Case study interviewee 0041 Trial Staff (clinical/research)

  Useful feedback

“But the other thing also, the measure is satisfaction by the patients, we have a very comprehensive survey about that. We measured what features are important to them and how well did we do in that category? So, we discovered that, for example, that being able to see your own measures was really highly valued.” Case study interviewee 0015 Trial Staff (technology/data)

  Targeted recruitment

“My role…was really to go and recruit the patients, first of all, from lots of different GP practices. So, we had to go out and do a search so the IT team had a search that we could go out and run on the computers, so it was actually on, I think, a portal….Then once we found the patients, then we had to send out letters… Then we had check the replies, then…The ones that had wanted to take part, we would get in contact with them, either by phone or email and then we would need to go and organise to go back to the practice and to screen these patients.”

Interviewee 0008 Trial Staff (clinical/research)

“…Recruitment was done all through social media and we contacted support groups, and we the head representatives go out, they have an annual, one of the support groups has an annual conference so they went out, they set up a booth...”

Case study interviewee 0021 Trial Staff (clinical/research)

 Burden of DCT participation

“We said, why don’t we try throwing the kitchen sink at it? So, let’s do remote tele-health monitoring with some virtual devices. We had the patients take their blood pressure remotely, take their weight, their pulse, the glucose metre and… we developed an app for the study, the patients would use on their phone and the app had many functions but basically the patient could log on every day, do their e-diary and that would be reviewed when they were doing their remote vital signs, their other protocol procedures…it’s a lot”

Case study interviewee 0044 Trial Staff (management/administration)

“We got their feedback on the devices… nobody really loved the biosensor, that they had to wear it stuck on your chest, it had flashing lights on it, you could see the lights through your shirt.” Case study interviewee 0053 Vendor

  Familiarity with study activities and technology

“So, they were not always necessarily familiar with the technology, right? And so that could have been, could be a reason for challenging patient recruitment.” Case study interviewee 0029 Trial Staff (management/administration)

  Simple instructions and interfaces

“Yeah, so that was all in the patient portal. So, in the patient portal there was a graphic that showed them where they are, what to do next…Then there was a messaging function. So, through the messaging function there was a secure chat in the portal that they could use to reach out to the study team. They also had a phone mechanism to call if they have a question.”

Case study interviewee 0015 Trial Staff (technology/data)

“In the beginning we also had some issues and, for example of a bad practice, so when you go into the online environment people can easily misunderstand things and you have to be very careful with your wording… So, one of the questions we had in the pre-screener which made a lot of sense to us but not to our users.” Case study interviewee 0015 Trial Staff (technology/data)

  Participatory choice

“So, for patients that were comfortable using the internet they were able to complete the visits on their own. We didn’t want to restrict in a socioeconomic way…So there is a way for patients once they are enrolled for the central call centre at [...] to call and help facilitate completion of follow up visits. Just so that the patient either did not have consistent access to the internet, or was not comfortable using the internet, that they still had a method for participating in the study.”

Case study interviewee 0016 Trial Staff (management/administration)

 Trust

“What we found is successful…is even in a virtual study patients want to know that their clinicians…support them during the clinical study and support them doing something different… So even in a virtual study where you are able to identify patients probably you still need to engage clinicians and have that support and buy-in and be able to support that relationship between eligible patients and their providers.”

Case study interviewee 0016 Trial Staff (management/administration)

  Communication

“Our patient partners were also really critical in the design of the recruitment materials. So, again you think a lot of recruitment materials at least in the US, there's a lot of language… it's got a lot of text…they felt that if we were going to be approaching patients remotely, either through email or through regular mail, phone calls that we really had to let a patient know very quickly this is a clinical study, this is the goal of the clinical study and who we are looking to enrol...”

Case study interviewee 0016 Trial Staff (management/administration)

  Maintaining contact

“We made sure that we would help retention by keeping contact with the patient. They received letters from us every second month, they received Christmas greeting cards, newsletters, stuff like that. And we contacted them whenever there was suspicion of an end point.” Case study interviewee 0017 Trial Staff (clinical/research)

“Then for retention, we talked to our patient partners about how do we make sure that patients want to come back and complete follow-up visits? How do we keep them engaged when they are not going into the clinic and seeing people and building that personal relationship? And so, we developed a participant newsletter, and our patient partners helped to develop the different sections of the newsletters.” Case study interviewee 0016 Trial Staff (management/administration)