Intentional and actional components of engaged participation in public health research studies: qualitative synthesis of a recruitment and retention process into the theory-informed INTACT-RS framework

Successfully recruiting study participants and ensuring their motivated participation is a key challenge in planning and conducting health research studies [1‐3]. In clinical trials, recruitment often occurs through direct patient contacts, calls for participation by clinicians, or pre-existing databases. However, previous findings indicate that although these measures can improve participation, reaching an adequate sample size and representativeness remains difficult [4, 5]. In public health research, a range of options for recruitment are available, too, but limited resources– particularly in smaller, qualitative research projects – or the lack of direct benefits for participants make this process challenging [6, 7].

Unsurprisingly given the significance of this topic, there is a considerable body of research about the design and organization of recruiting processes: Various systematic and scoping reviews have summarized barriers and facilitators based on individual descriptions of what works and what does not [5, 8‐10]. Other studies have reviewed specific methods, e.g., the use of social media for recruitment [11‐13], or the development and application of recruitment incentives [14]. Others again have directly assessed target groups’ perspectives on recruitment, mainly trialists and principal investigators [15], doctors and other healthcare professionals (HCPs) [16‐19], and lay people [20‐22]. Further studies have analysed recruitment strategies qualitatively and quantitatively, looking at recruitment data retrospectively [23] and statistically [24, 25], reflecting on self-experienced recruitment barriers [26], and describing the use of modified recruitment processes [27].

Lastly, some studies suggest how recruitment could be improved, by tabular summaries of identified recruitment facilitators [17, 24, 28], structured recommendations for the recruitment process [16, 29], and ‘principles’ and ‘frameworks’ for specific aspects, e.g. sampling framework [30] and recruitment maximization [23]. A Cochrane review provides a “Will I take part” conceptual model, which, based on qualitative evidence synthesis, describes five decisive determinants (effective trial communication, feeling nothing to lose, chance to help others, feeling something to gain, encouragement of other people). The authors also provide a comprehensive list of questions recruiters and trialists can consider when planning for recruitment, e.g., “will trialists aim to minimize time commitments?” and “will trial information be delivered verbally with face-to-face contact?” [5].

These and related contributions seem first and foremost to draw their conclusions from the perspective of researchers based on current recruitment practice. The aim of our study is to take the perspective of potential study participants who are considering taking part in the study. For them to make a decision, their attention must be aroused, and they must develop interest and motivation to participate, based on the subjectively expected effort and benefit. Therefore, explicit clarification of what is important and persuasive to people is needed to elicit engagement, and there needs to be a better understanding of psychological processes determining how individuals decide. Thus, a theoretical basis is missing to describe decision-making processes of potential participants and to explain their influence on engaged study participation. This clarification is essential to develop target group-specific recruitment strategies. Further, previous research has shown that those who are intrinsically motivated participate with greater concentration and invest more time in their participation [31]. Hence, interested and motivated participation may be essential to the validity of collected research data [32, 33].

The research network (HELICAP) comprises six independent research studies, four of which involved recruitment activities (see Table 1 for details). Study 1 examined how pediatricians and midwives consider parental health literacy during their counselling on allergy prevention. Study 2 and study 3 investigated parental health literacy, by analyzing knowledge, (information) practices and needs regarding allergy prevention. Due to the pandemic, both added Covid-19 infection prevention as a second use case. Study 4 related to the accompanying research done by the research networks’ coordination centre, aiming to establish a “parent board” to facilitate patient and public involvement. Overall, while each recruitment entailed multiple formats and target groups, we relied on similar recruitment principles according to the framework described below, and aimed to create organizational synergies, for instance by applying a common contact management database.

In a first step, we developed the conceptual framework: We reviewed existing psychological models of health behaviour that explain the development of intentions and the planning and implementation of behaviors [40]. The social cognitive process model of health behavior [39] – confirmed many times subsequently – includes a health behavior theory that differentiates pre-intentional motivation (intention formation) and post-intentional volition (initiation, maintenance) [41]. This conceptualization relates to the topic of recruitment, as initial non-willingness needs to be changed to successful participation, and hence HAPA is a suitable theoretical basis for participation behaviour. Since more recent literature focuses directly on facilitators of study participation, we further specified the framework with respective constructs; i.e. we reviewed (recruitment) literature that includes conceptual approaches to (potential) participants’ consideration and appraisal processes [5, 7, 8, 27, 42, 43] and included these elements into the framework. For instance, the phase of intention formation relates to aspects of attention, credibility, extrinsic and intrinsic interest, and appraisal processes being determined by interaction with the social environment.

In a second step, to further define and inform the theoretical framework components with empirical evidence, we followed basic principles of thematic- and qualitative content analysis (QCA) [44‐46]. QCA is an established method for analysing qualitative data – here, participant responses – as it allows for structuring and assigning text-based data inductively or deductively and to identify patterns in the data. First, female and male researchers from all studies (Master or PhD degree in Public Health; JL, AH, JvS, AAS, CD, HA, GS) compiled all recruitment-relevant responses from study participants (study 1-4, Table 1), including the sources and (researcher’s) notes that documented the study and recruitment planning (step 1: initial text preparation). Also, we prepared the table of 15 framework components to serve as deductively-derived main categories (step 2: category building).

Then, two researchers assigned available material – mostly single sentences built the unit of analysis, more sentences were added when further understanding was required – from each study reported here to the 15 components (Supplement 1). To do so, we identified (coded) a keyword or key-phrase in each quote/quote passage, using a pre-defined data extraction template in Microsoft Word. Based on the keyword/code, we preliminarily assigned each quote to the most suitable framework component and resolved remaining and unclear quotes by discussion with three further researchers (step 3: coding). As a result of the assigned text material, we also identified main- and sub-components of the framework (see below).

Next, according to the category-based overview of the material, we drafted broad summaries of each framework component according to a) participants’ behaviour during recruitment, and b) actions taken by the recruiters. We then identified similarities and differences for each recruitment process (studies 1-4) and, based on that, iteratively refined and complemented each components’ description (step 4: analysis – component-related thematic summary). The analysis was carried out in accordance with the criteria for reporting qualitative research provided by Tong et al. [47].

The results section includes all framework components highlighted in grey, for which data from at least three studies described here could be applied. All other model components are summarized in Table 2, with a full description in Supplement 2.

The analysis of the target groups’ participation considerations revealed indicators for all components of the INTACT-RS framework. This provides exemplary information about motivational and actional processes, which are decisive for committed research participation from the perspective of participants. While parents and HCPs may not be perceived as “hard to reach” groups per se, we expected recruitment to be challenging [9, 23, 26] and aimed to understand this process.

The literature mostly addresses recruitment barriers and facilitators [25, 29, 50]. Regarding barriers, those that are repeatedly mentioned across studies relate to (insufficient) recruitment training, including communication skills vis-à-vis study participants, the complexity, length, and availability of study information, available recruitment resources, concerns within the target group about why and how to participate, cultural and/or language-related factors that hinder participation, and the availability and appropriateness of incentives [9, 15, 17‐19, 24, 28, 50]. These barriers are often grouped according to different levels for which barriers can occur, i.e. study-related, design-related, recruiter-related, and participant-related [15, 18, 24]. Our article instead focuses on overcoming obstacles to successful recruitment by setting starting points for action (supplement 3). Also, even though we identified barriers and facilitators in the pre-intentional phase, it can be assumed that they predict volitional abilities that only appear after intention formation [35, 39]. This is because barriers and facilitators determine when and under what conditions an action is initiated and formed. Hence, and according to the original HAPA model [39], this framework component may rather need to be located in the intentional and actional phase.

Besides factors such as recruitment channels, methods, and necessary prerequisites, INTACT-RS shows that there is a different way of understanding what can hinder an individual’s participation when going into more detail, e.g. insufficient attention to the opportunity to participate in research or a negative perception of one’s own ability to participate successfully. Hence, emphasizing psychological and behavioural aspects of ability, coping, motivation, interaction, decision making and action control can be important; in the context of citizen science, Lotfian et al. [43] mapped reasons that would motivate participation by individuals into a framework of intrinsic and extrinsic factors, which relate to the interest components (thematic, supportive, gratification-oriented) of our framework in a similar way. However, with our own findings we hope to demonstrate that motivation is (only) one, though important, part of a more holistic approach to better integrate psychological and behavioural aspects in the planning and conduct of research.

The analysis of barriers also typically centres the (ongoing) recruitment process, e.g. in terms of information material or communication with potential participants. However, when applying INTACT-RS, it became clear that participants’ appraisal and consideration may already happen prior to engaging in communication with the research team about how and when participation is possible, and a final decision e.g. about continuing in a follow-up is made with some (temporal) distance.

An even greater proportion of existing studies recommends recruitment ‘facilitators’. These often relate to retrospective descriptions of what researchers and recruiters considered helpful, i.e. experience-based recommendations [19]. While various facilitators have been identified for specific study settings and objectives, such as recruitment during unscheduled hospital admissions [29], reviews reveal various generic facilitators: cooperating with a HCP to approach target groups (doctors for clinical trials), directly and personally approaching potential participants, strengthening recruitment skills of those who do the recruiting, sufficient allocation of resources for recruitment, and selecting a specifically suitable recruitment site. Research has also identified participant-related reasons for joining research studies, particularly the desire to help others, face-to-face interaction with recruiters, and receiving a recommendation from peers. However, such rationales are mostly inferred from researchers’ observations and experience, and without taking a more structured, inclusive perspective of the spectrum of (all) potential determinants.

In our research, we related potential recruitment facilitators to each component within INTACT-RS to enhance understanding of the perspective of (potential) study participants. In fact, there have been valuable previous efforts to incorporate participants’ perspectives about recruitment in a framework, for instance for “Rationale for research participation framework” by Weller et al. [51]. While this specific framework example entails reasons for participation, e.g. participation to help others, we focus on the steps and phases potential participants go through, so that researchers can directly align their respective measures and steps for recruitment and study conduct to each component. In that sense, using empirical insights about what facilitated recruitment and retention, we formulated a total of 41 recommendations alongside the framework components, i.e. considerations that may be taken up by researchers (Table 3). The component ‘barriers and support factors’ is considered separately from this checklist in supplement 3.

Looking at pre-intention, we could relate this phase to some of the previously established facilitators, particularly the help of recruitment partners such as health- and social care facilities that are in close contact to target groups [17], or the benefits from direct, personal contact to desired participants [52]. However, firstly, public health research often relates to topics that are not inherently medical, which may be out of scope of those working in a healthcare practice. Secondly, (potential) participants strongly welcome feedback from institutions they trust [20] for instance to appraise credibility and utility. Nevertheless, we realised that, due to workload, e.g. pediatric practices can provide little assistance despite their proximity to parents, while (medical) umbrella associations were rather helpful to approach HCPs. Therefore, and somewhat in contrast to other ‘classic’ means to increase attention, such as the allocation of resources [15] and training [28], our own efforts focused on directly appealing to an individuals’ awareness, motivation, interest – for instance by relating the study’s topic more closely to current interests, questions and possible concerns prevalent among the (distinct) target groups.

As outlined above, (previous) recruitment research first and foremost addresses aspects related to recruitment planning and ongoing recruitment as such, including but not limited to the identification of effective recruitment channels, recruitment staff, methods for approaching individuals, and the design of recruitment information materials. While these factors relate to the crucial phase of raising attention, INTACT-RS attempts to enhance this step via the phases of intention formation and action. Regarding the former, we identified various aspects (framework components) that can no longer be ascribed to initial attention and awareness, but that only evolve when individuals plan for participation in more detail, e.g. handling of technical and organizational resources. The examples of facilitating an individual’s planning by providing participation alternatives (e.g. mode of participation) when necessary and reducing doubts about being able to participate successfully through personal and direct assistance, illustrate that individuals relate their successful participation in research to aspects beyond initial interest and that cannot be covered only by the allocation of recruitment resources, the support from recruitment partners, etc.

Regarding the latter – the actional phase – while participation already takes place at this stage, recruitment and retention are still relevant, particularly because of participants’ subsequent decisions: to continue with the study, for instance in subsequent data collection or follow ups, participants reconsider interest and motivation, i.e. compare expectations with actual participation. To recommend (or not) participation to others, participants require a clear understanding of the importance of this task for the success of the study and hence, specific advice on how they can contribute to this. Given the continuing discussions about effective recruitment strategies (e.g. [9, 25, 53]), it may be legitimate to integrate these and related aspects (see Table 2) into study planning, rather than (only) focusing on ‘how’, with what means to approach potential participants (e.g. [18, 26]). Previous work by Nov et al. [54] highlights how (initial) motivations, interest, etc. impact on the (subsequent) quantity and quality of participation, providing another argument for why it is important to use a more comprehensive framework.

INTACT-RS supports the validity of the collected data in addition to the general willingness to participate. In particular, the validity of questionnaire data that assess subjective judgment and perception is promoted by motivated and serious study participation. Response biases such as halo effects, self-serving biases and sequential effects occur especially when participants tend to answer in an unfocused, facile manner and in the mode of impression management [55]. Also in qualitative focus groups, the interest, motivation, and mutual perception of the communication partners moderates the validity, depth, and sincerity of the individual responses [56]. The better the process elements explicated in INTACT-RS are accounted for, the more likely the specific item contents may be processed in depth and seriously considered.

While INTACT-RS relies on a the previously established HAPA model [39], its further application will reveal new insights and its individual components, though justified by empirical evidence, may not be exhaustive. Based on the available data, some components could be characterized in more detail (e.g., interest) than others (e.g., maintenance motivation). Hence, QCA is useful to indicate an overview/spectrum of topics – here, recruitment challenges – but cannot fully validate a framework, also it implies some degree of giving meaning to participants’ statements as part of the coding process. Further empirical testing is needed to clarify which framework components are a) valid main indicators of active participation and b) predictors of a valid data situation. In addition, it still needs to be determined whether the components’ relevance differs depending on the target group. A structured assessment of the perspective of how study participants – and possibly researchers perceive each component, may induce changes to the framework. Since we advocate here for strengthening participants’ perspective on recruitment and retention, active involvement into the frameworks’ further development seems indispensable. This would also be important since the studies underlying the recruitment processes assessed parental information and prevention behaviour, not study participation intentions, decisions, etc. and could hence be interpreted as ‘secondary’ data. While for instance an assessment of non-response reasons – which this study does not entail – would further objectify the reasons for or against participation, even the responses gained from this research reveal the many hurdles of attracting (potential) participants’ attention. These desiderata constitute the prerequisite for identifying interventions that promote the motivation- and interest-related processes postulated here.

Though it is (potential) research participants who eventually agree to or decline study participation, previous research often emphasizes what research and recruiters can do to facilitate recruitment. Also, taking part in research does not only relate to successful recruitment, but entails phases before and afterwards. Therefore, INTACT-RS aims to increase the integration of basic behavioural and motivational components which inform an individual’s decision-making, to enable a systematic recruitment and retention approach.