Table 3 Themes describing what constitutes retention and the associated belief statements; RET-00 = retention staff participant ID, REC-00 = recruitment staff participant ID

Retention is not an equal priority to recruitment

I think that what retention encompasses and why it is important is not emphasized to us (Knowledge)

“That just seems like a huge waste of everybody’s time, you know, we really need to do more to make sure that people understand about retention as much as they do about recruitment. But things don’t seem to be geared that way at the moment.” – RET-02, trial manager

We do/ do not always know what the alternatives are to full participant withdrawal (Knowledge)

“I did get quite a lot of, especially in the early days, there was quite a bit of grey area for patients withdrawing or simply changing status, or how did we find out, sometimes it was difficult to know if we just found out from a practice that a patient no longer wanted to take part on the trial, what did that mean exactly. And we weren’t sure if we would be able to actually contact the patient to ascertain what no longer taking part to them meant.” RET-03, trial administrator

I am not sure that how I try to retain participants is effective (Beliefs about consequences)

“R –Do you feel that discussing completing study follow-up with potential participants during recruitment, do you think it makes a difference to retention overall, in your trial?

P – I’m not actually sure. No, I’m not sure about that one actually. I don’t know. I’m trying to think of examples where I maybe have in the past, but I don’t know whether that’s been a specific thing that’s give patients on a trial or not.” – REC-06, research nurse

It feels that some of my colleagues do not consider retention as part of their role (Social professional role and identity)

“I think being upfront with sites because sites are the ones that are recruiting and make them more responsible for retention as well. Or more – not more responsible, making them work with you more because I think there is that cut-off where they recruit and then they think you retain. I think it’s maybe trying to work with sites a little bit more to try – because I definitely think there’s a them and us.” – RET-01, data coordinator

Training that focusses on retention should be provided to me and/or my colleagues (Behavioural regulation)

“I think it would be useful actually, I think it would be something that would be good for the whole department. I think that perhaps there may be a lack of understanding from some people about exactly what retention is, what it means in terms of the work that we do and just the implication that that can have. I think there could probably be some really good examples given to highlight the difference in what the end result might be from a trial.” – RET-02, trial manager

Effective relationships are key to retention

We should be able to establish and maintain effective relationships with participants over time (Skills)

“I guess, as well, part of the retention process is trying to be a sort of a contact point for people, so that hopefully if they have any worries, queries, concerns, throughout their time in the study, they have that central contact point off me as the research nurse. Hopefully, it puts more of a human spin on things for them, and hopefully makes them feel that this is not just them as a number, but that we do see them as an individual.” – REC-14, research nurse

When we maintain relationships with participants and emphasise the importance of their participation, it contributes to retention (Beliefs about consequences)

“So, there’s all those things going on but there is also that human element of the person who’s giving us their consent. Feeling comfortable with remaining with the trial, feeling that they are valued, feeling that they understand what they are giving us, and what’s happening to them. That’s very important […] that people feel valued and understand why they are important in the context of the trial … I think are important elements of retaining them.” – RET-04, trial manager

The relationships we establish and work to maintain with participants are crucial to retention (Social influences)

“Well I think probably like a psychological influence if you develop a nice rapport with the patient. A lot of patients I give them… they know my… although I’ve recruited them to the trial, that is my remit finished, that was my remit finished for [HOST TRIAL], everything was done from me collecting data on them rather than me seeing them throughout the trial, but I always make sure that they’ve got my contact number and if they’ve got any issues then they’re free to contact me, but I won’t be contacting them but they can contact me. I think if you develop that rapport with the patient and give the patient that bit of security, that they’ve got your number and they’ve got you as a back up, then I think they’re more likely to complete the trial for you.” – REC-15, research nurse

I enjoy my relationships with participants and that encourages me to retain (Social influences)

“And then, for me as a person as well, I always think it means… it gives you, as a researcher, the chance to go back to that participant, whether you’re seeing them in person for the follow-up or even it’s just on the phone. But just to know how they’ve got on, how they are, and to maintain that relationship with them. The follow-up allows for that relationship to continue, so that is an additional incentive and that’s a very important incentive for me too.” – REC-07, research fellow

I am motivated by positive interactions with participants and other staff (Reinforcement)

“Oh, to retain them. I suppose if they’re nice, it helps! It encourages me to retain them because I’m a nurse and I want to move things forward in clinical care. I wouldn’t like to think that we’ve put all this energy into trials and then we didn’t get the answer, that’s why we’re here.” – RET-05, senior research nurse

Support from my local colleagues and central trial staff improves my ability to retain (Social influences)

“I think I’ve gained… I genuinely feel that I’ve gained a better understanding of that through being faced with the muscular skeletal research unit here. I think because it’s an academic unit and you are working with so many different professionals who are all involved in a research programme, I think it gives you a bigger picture, as opposed to being a recruiter within… my other role, I guess, is more we are delivering studies but a lot of it is focused on recruitment and delivering, I don’t know, the day to day study processes.” – REC-14, research nurse

Communication is the cornerstone to promote retention

We should be able to communicate what participation involves early and explicitly (Skills)

“No, I think it’s part of the interview and the consent that they understand there will be follow-ups and how many follow-ups and how long will they take, so when they consent it’s what I call a valid consent, they understand not just the study, but they understand what we want from them for the whole of the study.” – REC-10, research nurse

When we set realistic expectations with participants about what trial participation involves, it leads to improved retention (Beliefs about consequences)

“But I think it is managing expectations, really. If you’re going to tell people it’s a really quick questionnaire and then they’re going to get 30 pages plus, you know, it does affect their trust in you and their likelihood to want to carry on because they think, well, she said this. But now I’m having this. What’s it going to be like next time? So, yeah, I think it is managing expectations probably be the absolute main thing, really that you need to do.” – REC-03, research nurse

A sense of agency informs the belief that what you do matters to retention

We try to accommodate our participants in order to improve retention (Goals)

“And then other things like you know, for me I tried my best to accommodate patients if they weren’t able to attend an assessment, we, and as a team, we tried our best to go back to a practice, especially if the first set of assess… final assessments you know, there hadn’t been a good turnout we tried our best, and level best, to get as many people as we could to return for those assessments.” – RET-03, trial administrator

I think flexible follow-up options help with retention (Environmental context and resources)

“I think it’s pretty well set up in terms of… from recruitment it’s really quite flexible from being able to recruit patients virtually or face-to-face. In terms of retention, as well, everything’s done via the clinical pathways, so there’s nothing extra that they’re having to come in for, that we’re having to see them for, so because it’s done, we’ll see them at a visit that they’re into see either the surgeon or a nurse specialist. You know, we can catch up with them at that point: we’re not having to invite them in on top of that. And there’s things that we can do virtually as well: we can go over questionnaires on the phone with them, we can post things out, and they can post things back, so I think the design of the trial is quite good and it allows flexibility for patients to be able to sign up and not have that massive commitment where they have to attend hospital several times in the trial.” – REC-06, research nurse

I think there are changes to study documents that could better emphasise retention to both us as staff and participants (Behavioural regulation)

“I don’t consciously think, “I don’t need to worry about this bit, this is less important,” but I think the fact that it’s further down the consent form probably reinforces… these are the bits you really, really have to make sure go in first, these are the bits that you don’t need to worry about so much. I don’t mean you don’t need to worry about them, I just mean it feels like if you present me a consent form in this order, this is the order of priority as determined by the study designer. One thing that I do think about follow-up is that of all of the statements on the consent form, the follow-up is often the most convoluted.” – REC-13, research nurse

I think questionnaires are confusing/cumbersome for participants (Environmental context and resources)

“I mean, comparing [HOST TRIAL] to some other studies I’ve had which have been 30 pages of questionnaire on one side injury and then 30 pages on the same limb but on a different side. And they would get a lot of reminders to fill out these questionnaires. There would be a lot of questionnaires and I think you lost patients that way because they didn’t want to fill out the questionnaires it was boring. They were doing, you know, where there’s [HOST TRIAL] it’s not having that – fewer questions is definitely helpful.” – REC-03, research nurse

I think there are ways for us to deliver questionnaires to participants that would make it easier for them to complete and return them (Behavioural regulation)

“Yeah, but with [HOST TRIAL] all they had to do was fill in maybe ten pages of questions, tick box, the envelope was sent to them and they just posted it, they didn’t need to pay any postage, they got a voucher if they completed the questionnaires. So [HOST TRIAL] really you know, yeah, was a good study to recruit to and a good study for retention.” – REC-15, research nurse

I think participants’ competing priorities from ‘real life’ context can be a barrier to retention (Environmental context and resources)

“Plus, I think all of our trials are trauma studies so they’re not really the best situation to be giving somebody a lot of information. They’ve just had an unexpected injury, they’re probably in quite a lot of pain, probably also had some painkillers which might mean that they’re not thinking as straight, so I think there’s a lot of times where, actually, we’re giving these people all this information. I do think that often, the follow-up information can kind of get lost between everything else, because they’re more thinking about, ‘What treatment am I going to have right now?’ rather than, ‘Oh, you’re going to ask me some questions about it in a year’s time.’” – REC-02, research physiotherapist

It feels like our participants’ motivation to be in our trial, not necessarily how motivated we are, predicts whether we can retain (Intentions)

“Often, I’ve found participants are keen on the intervention, but they’ve been put off by the intensity of the work… of the burden of the follow-up – the questionnaires, interviews. Not so much the visits or the appointments, but when they’ve got to do things, like complete things, and send them back to you, or sit through an interview with you and things, and that can… I think if someone’s going to take part in, or… sorry, I think if someone’s going to decide to leave, they’re going to leave that process anyway irrespective of the researcher.” – REC-07, research fellow

Retention can be stressful/frustrating for me (Emotion)

“I feel happy if I can retain participants in trials. If we go to the effort of keeping patients in trials and they don’t turn up for visits, that makes me quite angry. It has a knock-on effect with every other trial that I do. I feel it should be reiterated to patients that it’s a hospital and they can’t just not turn up for appointments.“ – RET-05, senior research nurse