As part of the triangulation procedure, the results of all the analysis steps and data sources were merged and interpreted collectively. The results for identified factors that promote or inhibit the recruitment of healthcare providers will be presented first, followed by a brief overview of the results for the recruitment of patients by healthcare providers. The interviewees' suggestions for improvements to the recruitment process will be presented last. Additional File 3 details the final system of thematic categories.
Facilitators for the recruitment of healthcare providers
All the interviewees described the intrinsic motivation of healthcare providers as the most important factor for active participation in the trial. For example, one study coordinator provided the following assessment:
"For them, the focus is on perinatal programming, so they also know what responsibility the physician has [...] during pregnancy to address this [...] Yes, they have understood the importance of these topics and it is important for them. And that is the main motivation to participate in GeMuKi.” (study coordinator 1_paragraph 16)
Intrinsic motivation thus includes an interest in the trial topics and a perception of them as important and relevant to regular care. It indicates the physicians’ need to improve the care provided to their own patients and to contribute to the development of their profession. Additionally, intrinsic motivation involves a general openness and curiosity with regard to new learnings and being up to date. The respondents also addressed extrinsic motivational factors that led to participation in the trial. In particular, these included: financial compensation, continuing medical education credits, regional peer group dynamics, and professional-political mandates. However, the respondents claimed that these factors played only a secondary role in the decision on active participation. Although some statements indicated that the financial compensation should have been higher, there is an agreement that the financial aspect was not a decisive reason for whether or not a healthcare provider participated.
“No one would have taken part for the sake of money, in order to pimp their salary a bit. I do not see that at all”. (study coordinator 6_paragraph 8)
Some of the reported facilitating factors for recruitment relate to the general set-up of routine healthcare practice. For example, recruitment was reported to be easier if healthcare providers were already addressing the trial topic as part of their regular care prior to entering the trial. All the interviewees cited convincing healthcare providers to participate in the trial within a short time frame as their most difficult task during the recruitment process. For example, they mentioned the importance of highlighting different information in the intervention and control groups and adapting their communication strategy accordingly. The amount of information relayed was thus scaled down to a minimum for busy practices, while more detailed explanations on the trial were provided when there was more time. Overall, the study coordinators emphasized the importance of efficient and charming communication when it came to recruitment:
“When I was out and about a few times for cold calls, at the beginning you're still a bit shy and at some point you know what you have to say to somehow get the people. So I think there is a lot of intuition and also empathy, on whom you encounter there and whether it then just falls on deaf or on open ears.” (study coordinator 5_paragraph 44)
Interviewees agreed that, in terms of promoting the trial among gynecologists at the very beginning, visits to quality circles and Stammtisch events were beneficial for recruitment.
Barriers to the recruitment of healthcare providers
The major inhibiting factor was a lack of time. This factor results from the general set-up of healthcare practice. In many cases, the study coordinators reported that there was no time for additional tasks that went beyond standard care during a busy everyday care routine. In addition to this, many practices are working at the limit of their capacity, so additional time spent on individual patients due to trial tasks results in other patients not being cared for. The study coordinators therefore see the additional workload caused by the trial as the most critical barrier to recruitment. During the course of the recruitment activities, the gynecologists complained to the study coordinators about trial-related processes and additional workload – enrollment, documentation and counselling – which was perceived as not being manageable. In this context, the interviewees also mentioned that some healthcare providers considered the financial compensation for trial effort to be too low. Another factor reported in this category was the digital implementation of trial components (digital data collection platform), which in some cases led to a rejection of participation.
Additionally, the study coordinators describe barriers to recruitment that either arise from the relationship with the healthcare providers’ professional association or are related to professional policy. The factors mentioned here related to the relationship between community-based gynecologists and their professional association: The interviewees reported that the actual target group, community-based gynecologists, did not feel sufficiently involved in the planning of the trial. Community-based healthcare providers in the study regions were not involved during the planning phase, though members of the German Professional Association of Gynecologists (Berufsverband der Frauenärzte) were present at trial meetings. Furthermore, according to some study coordinators, the professional association should have invested more in the motivation of its members.
The interviewees problematized particular organizational aspects within the team of study coordinators. Interviewees reported that it was often not possible to get clear approvals or rejections for trial participation from healthcare providers, even after repeated contact attempts. In these cases, there was a lack of clarity as to how many contact attempts should be made before a practice could be classified as not recruitable.
"So I couldn't tell the physician assistant anything more about it, she had already heard from me several times, HAD already presented everything to the physician [...], but there was no final feedback. Then [it] was just: Okay, do I remove them from the list? Better not do it? That was always the decision. I think many of the study coordinators then immediately deleted the practice." (study coordinator 1_paragraph 51)
Another main difficulty in the recruitment work was seen in information management on the part of the physicians’ assistants. This includes getting the information to the right person at the practice. In most cases, the initial telephone contact was made with physicians’ assistants. Often, the physician’s assistant acted as a gatekeeper. As a result of this, it was not possible to speak directly with the physician or practice owner. Frequently, the extent to which the information was passed on by the physician’s assistant was unclear.
"[...] then you just have some physician's assistant on the line. Well, they don't tell you their NAME on the phone, they simply say "Practice such-and-such" and until you somehow get through to the one who is responsible [...] That really sucks (laughs lightly) [...]? If you then called them, they didn't know about anything and until/ I was (...) VERY, VERY rarely put through to the physician at recruitment and [...]/ I don't even suggest that anymore. There's no point." (study coordinator 4_paragraph 10)
The interviewees also reported that characteristics of the respective patient clientele influenced the recruitment of healthcare providers. The responses revealed a contradictory picture: On the one hand, some interviewees reported that healthcare providers refused to participate because they did not see a need for the intervention among their own patients. On the other hand, participation was also rejected if a high need was seen. The physicians in the latter group assumed that there were too many other burdening factors in the patient's life situation, as a result of which the lifestyle intervention was not seen as useful.
“And the other one said he had mostly junkies […] and he said "They have such a social burden; I don't know at all where to start with counseling.” (study coordinator 4_paragraph 50)
The interviewees also discussed factors that led to the active recruitment of participants by healthcare providers. Since the focus of the article is on the recruitment of healthcare providers, results that relate to the recruitment of patients will only be presented in brief. Nevertheless, this information is important, as it has a considerable influence on the motivation and activity of healthcare providers during recruitment processes.
Facilitators for the recruitment of patients
The interviewees outlined aspects of practice organization that could have a beneficial impact on the recruitment of patients. Well-organized and efficient working practices in general and the involvement of the physicians’ assistants in the trial tasks were mentioned. In this context, most study coordinators believed that a division of the trial tasks among physicians and physicians’ assistants and a close exchange of information between these two stakeholders facilitated the recruitment of participants. Overall, all the interviewees reported that stakeholders recruit more actively the less effort the trial requires from them. They also assume that recruiting patients is easier if the study only implements minor changes to existing routines. One interviewee provided the following statement on this topic:
“In my opinion, what helped most was that we took the [digital] documentation off their hands, [...] because these [paper-based data documentation] are processes that work in practice, which are tested, like writing by hand and faxing things. [...] Yes, that was actually the main incitement.” (study coordinator 6_paragraph 38).
The option of including all patients with statutory health insurance and the paper-based data documentation option were described by the study coordinators as promoting patient recruitment. Other strategies for enhancing patient recruitment (see Recruitment in the GeMuKi trial) were rated as having little or no effect.
Barriers to the recruitment of patients
The study coordinators also named factors that impeded the recruitment of participants by healthcare providers. The major factor was rejection by potential patients. The reasons given for this included concerns regarding data privacy, a lack of interest in the trial topics, and the assumption of low benefits in return for high effort. The study coordinators reported that some healthcare providers lacked the requisite arguments and techniques to convince eligible patients to participate in the trial. Repeated refusals by patients have a negative impact on the motivation of the stakeholders, and lead to frustration and inactivity in the long term.
Inactive practices are practices that enrolled in the trial but did not recruit patients. In the GeMuKi trial, this applied to 43% of all the enrolled practices (see Figure 1).
The interviewees reported a lack of intrinsic motivation and, in contrast, predominantly extrinsic motivational factors for initial trial enrollment, such as collegial obligations or the free continuing education credits for practices that were inactive from the very beginning:
"With the practices that (laughs lightly) only participate out of somehow a sense of duty, because they are regional leaders or something, because they have the feeling "Yes, okay, I have to enroll in a trial", yes, or, yes, "I'm doing this here because it HAS to be somehow for the research", but who don't have such a real passion behind it, with them it's going slowly." (study coordinator 6_ paragraph 34)
Study coordinators mentioned that the reasons for practices becoming inactive during the trial were repeated rejection from patients and the complexity of the trial, which led to implementation problems. Furthermore, they reported that participating active healthcare providers feel abandoned in their region and become inactive due to frustration regarding the lack of engagement on the part of their colleagues.
Study coordinators’ suggestions for improvements
The interviewees were asked for suggestions and ideas for successful recruitment. Some study coordinators suggested higher financial compensation for the trial efforts. However, all the interviewees pointed out that high compensation alone would not be sufficient to achieve successful recruitment rates.
Based on their experience in recruitment organization, some study coordinators recommended fostering marketing and communication skills within the trial team. This would provide them with the means to design recruitment materials (e.g. flyers and fact sheets) communicate directly with the physicians' practices in as efficient and successful a way as possible. This recommendation was based on the perception that undecided actors could still be recruited using good communication skills:
"Perhaps I would consider whether I a) bring people on board who simply have recruiting experience or whether I first train them, learn communication techniques, because I believe […] that you can really still get people with words and with arguments. I mean, of course, those who really have ZERO interest or zero time, you bite on granite. But those who are still a bit undecided and actually already have an interest in the topic, but don't really (know what they are doing?), I think you can get through that". (study coordinator 5_paragraph 79)
Additionally, the interviewees viewed engaging staff members with recruitment experience related to the intended target group as a desirable approach.
Most suggestions for improvement related to the trial design. Various interviewees emphasized the importance of carrying out a carefully conducted needs assessment among the target group prior to finalizing the trial concept. For this purpose, the study coordinators recommended that the status quo and possible shortcomings in current care should be discussed with community-based healthcare providers beyond the professional associations. Moreover, the study coordinators stressed that all the relevant stakeholders needed to be taken into consideration, both in the trial design and in advertising and communications. The interviewees mentioned that, as important key players, physicians’ assistants should have been more central in recruitment efforts.
Furthermore, some interviewees suggested that the inclusion criteria for trial participants should be determined not only using scientific considerations, but also based on practicability in everyday care. In order to prevent frustration among the healthcare providers due to rejection from patients, the provision of an attractive incentive for patients right at the start of the trial is recommended.
Some of the suggestions for improvement related to the trial preparation workshop, which is a prerequisite for participation in the trial. Study coordinators recommended preparing information as concisely as possible in order to ensure that the relevant topics could be covered within an appropriate time frame. Another suggestion was to consider online formats for trial preparation.
In terms of the content, one study coordinator called for the inclusion of patient recruitment strategies in the curriculum:
"Because this is a scientific trial, after all, but we also wanted to sell that somehow, that the physicians do that. [...] all these recruitment strategies, these recruitment tips, [...] but somehow also explaining [to the physicians]: How do you recruit for a trial in the first place? Because they have 0.0 experience on that, yes." (study coordinator 1_paragraph 75)
This aspect was also discussed in the context of the fact that physicians seem to be reluctant to "persuade" their patients to participate in a trial and/or cease recruitment if multiple patients decline.
 Categories of the thematic analysis are presented in bold letters within the text.
 The interviews were conducted and analyzed in German. Two researchers translated the quotes independently.