Engaging People and Co-Producing Research with Persons and Communities to Foster Person-Centred Care: A Meta-Synthesis

Introduction: Engagement and co-production in healthcare research and innovation are crucial for delivering person-centred interventions in underserved communities, but the knowledge of effective strategies to target this population is still vague, limiting the provision of person-centred care. Our research aimed to identify essential knowledge to foster engagement and co-production. Materials and Methods: A meta-synthesis research design was used to compile existing qualitative research papers on health communication, engagement, and empowerment in vulnerable groups in high-income countries (HICs) from 2008 to 2018. A total of 23 papers were selected and analysed. Results: ‘Design and recruitment’ and ‘engagement and co-production’ thematic areas are presented considering the factors related to researcher–communities attunement and the strategical plans for conducting research. The insights are discussed in light of the literature. Long-term alliances, sustainable structures, and strengthened bonds are critical factors for producing real long-term change, empowering persons and communities, and paving the way to person-centred care. Conclusions: The enhancement of the recruitment, involvement, and empowerment of traditionally disengaged communities and individuals depends on the awareness and analysis of social determinants, power differentials and specific tactics, and the capacity of researchers and individuals to apply all these principles in real-world practice.


Introduction
Co-production and engagement of individuals and communities are critical for designing person-centred care, and they are even more crucial if the service users are socially vulnerable groups (e.g., traditionally discriminated or marginalised minorities, including racialised groups, deprived communities, or sexual minorities, among others). Vulnerability is understood as the result of specific socio-economic, demographic, cultural, institutional, spatial, and environmental contexts [1] encompassing the susceptibility to hazards, and then, the diminished capacity to cope and/or to adapt. Thus, "vulnerability" is opposed to "resilience", or the capacity of social, economic, and environmental systems for coping with hazardous events, disturbances, and adverse events, being able to respond and to maintain, transform, or adapt their basic functions, identities, or structures [2].
Traditionally discriminated, marginalised, or excluded communities are considered vulnerable in this article: the historical power imbalance might diminish the ability of these communities and individuals to cope with adverse events due to structural reasons. Other vulnerability conditions that are included are: (i) rural areas, due to their partial isolation and lack of access to key results [3][4][5][6]; (ii) youngest and oldest persons, due to ageism [7,8]; (iii) persons with diagnosis of mental disorders and people with disabilities, due to structural discrimination (mentalism and ableism), stigma, stereotypes, Hard-to-reach

Selection Process and Eligibility Criteria
As Figure 1 details, initial results showed 4026 references (3559 after deleting duplicates; 2729 after deleting irrelevant and non-related results) from 2008 to 2018, comprising the period of the economic and financial crisis. Since financial crises imply limited resources devoted to health promotion, investigating how to foster health communication, literacy, self-management, empowerment, and co-production in a period of crisis has a clear intrinsic interest. Hard-to-reach

Selection Process and Eligibility Criteria
As Figure 1 details, initial results showed 4026 references (3559 after deleting duplicates; 2729 after deleting irrelevant and non-related results) from 2008 to 2018, comprising the period of the economic and financial crisis. Since financial crises imply limited resources devoted to health promotion, investigating how to foster health communication, literacy, self-management, empowerment, and co-production in a period of crisis has a clear intrinsic interest. Papers meeting the exclusion criteria were excluded from the analysis (see Table 1). As a result, 458 studies were scanned and assessed for the final selection, considering the inclusion criteria and the quality control through the Critical Skills Programme (CASP) questionnaire for qualitative research papers. Finally, 102 studies meeting all inclusion criteria and rated as excellent (CASP ≥ 8) were included in the final sample. Papers meeting the exclusion criteria were excluded from the analysis (see Table 1). As a result, 458 studies were scanned and assessed for the final selection, considering the inclusion criteria and the quality control through the Critical Skills Programme (CASP) questionnaire for qualitative research papers. Finally, 102 studies meeting all inclusion criteria and rated as excellent (CASP ≥ 8) were included in the final sample.

Data Extraction and Analysis
PDFs (full texts of each article) were downloaded. Both the full paper as well as the section on Results were coded and analysed using MAXQDA (Verbi ®® v2018-2020) following a meta-synthesis method [29] based on the grounded theory. The grounded theory analysis is based on the lack of predefinition of the themes extracted: the rationale for this innovative approach is that the widely used principles of grounded theory could be applied to a large meta-synthesis in order to ensure that all meanings and metaphors are well captured, but at the same time, the structure of the information is comprehensive but still manageable in order to generate lines of argument and new models and implications for practice. Specifically, the grounded theory approach facilitated that codes and themes arising from the information and the materials were effectively related to each other, and then inter-translated and compared. The qualitative data was tagged according to those repeated ideas and emerging iterative concepts, following an inductive reasoning led by the materials themselves in order to generate the core lines of argument, and then middle-range theories [37].
The analysis was conducted on 102 selected studies. Among them, 23 studies were directly related to the following codes: 'recruitment for research', 'participating in research' and 'researching in the community'. Papers selected are cited within the Appendix B. Table 2 presents the studies' characteristics.  The sample analysed in the 23 studies selected covered qualitative data from 786 individuals. However, the figures behind the data remain unclear, since some research papers conducted a participatory observation of very large samples. The sample remains unclear because the audience of these meetings cannot be easily specified. Besides, 37 reports were included by the researchers, as well as 16 visits to stakeholders, and 10 organisations were studied.
It is worth noting that some studies included the general population and a vast range of healthcare users with different socio-economic and socio-cultural backgrounds-that may also entail traditionally discriminated persons and communities. These studies were included due to their conceptual richness and the inclusion of patients from all backgrounds. Table 3 sums up the sampled studies.   Aboriginal health. Health professionals from 2 urban and 1 regional Aboriginal Community Controlled Health Services (ACCHS) in New South Wales COMMUNITIES (*) Mental disorders, and in particular highly stigmatised ones (e.g., borderline personality disorder (BPD)), were considered as a vulnerability condition, due to the systemic discrimination that these individuals may suffer, but also because of their lower access to resources. In parallel, mood disorders and important emotional disturbances linked to the chronic condition were considered within these conditions. (**) Sexually transmitted infections (STIs) were considered a vulnerability factor for accessing healthcare and for participating in the research due to the stigma linked to these conditions, mediated by gender expression and sex. (***) Rural populations were considered vulnerable because of the difficulties in accessing healthcare and health literacy, lack of infrastructure, and tele-communications challenges, among other potential difficulties, such as impoverished or deprived socio-economic circumstances. [3][4][5][6]. (****) Caregiving for dependent persons had a direct impact on the household financial burden, as well as very particular employment and workload challenges, while also mediated by other structural factors mainly related to age and gender [38][39][40].

Results and Discussion
Twenty-three (23) papers matching the theme 'Research' were identified. The papers were related to:

1.
Designing and recruiting in research and healthcare innovation for person-centred care. This theme covered the first stages, from the design to the recruitment of individuals and leaders in the community, and how the plan itself, the participation, and the methods used during these phases could contribute to the improvement of the subsequent stages.

2.
Engagement and co-production as a means for empowering persons and communities. This covered the research and co-production conduction and how to engage individuals and engagement; thus, phases covered were implementation and, if applicable, evaluation, until the end of each study.
In addition, two analytic themes were used for classifying the information: facilitators and barriers. The constructed items also were classified as factors linked to 'communityresearchers attunement' and 'comprehensiveness of the strategic plans'. Each item contained into these two categories was re-interpreted and summarised to capture the key idea behind the statements analysed to make them operative for constructing middle-range theories (full quotations are shown in the complementary materials). Table 4 summarises the key facilitators and barriers (sources are quoted in lowercase letters to facilitate the distinction between the papers comprising the sample, cited in the Appendix B, and the general sources referenced).

Analysis of Design & Recruitment Factors
As facilitators, the texts analysed emphasised the importance of preparing the information with adequate and tailored content and format, adapted to the community to be reached during the design and recruitment phases (l)(m)(q)(t). It may also imply the cultural adequacy of materials, contents, and means used for their engagement. Enough information needs to be provided, always in an understandable way (l)(m)(q)(t). Community leaders and civil society organisations (CSOs) should be involved, and they can be essential to lead the recruitment, retention, designing of information materials, and dissemination of resources or the assessment procedures (q)(s)(t). It is also relevant to include in the design process an adequate budget planning, as long as the involvement of communities may imply a different allocation of resources compared with traditional methods (l)(p)(t). •

Researchers' factors:
Researchers able to involve the community from the design phase (l)(p)(q) Comprehensiveness of the strategic plans: • Knowledge and competencies for implementing methods aimed at ensuring an active involvement, and participation of key persons and leaders (q)(s)(t) •

Logistics and institutional factors:
Plan established for sharing results (p)(r)(t) Training foreseen or conducted for researchers in participatory research and co-production of healthcare innovation (p)(s)(t) Training foreseen or conducted for community members and participants involved (m)(p)

Barriers
Community-researchers attunement: • Individuals' co-determinants: Individual and personality factors that may undermine the participation, such as the lack of self-confidence (d)(q), or triggered by sensitive issues (i); fear of legal consequences (c) •

Communities' factors:
Distrust of community leaders and civil society organisations (CSO) based on the fear of more stigmatisation and stereotyping (k) ( •

Researchers' factors:
Conflicting agendas between researchers and communities (p)(t) Use of jargon, specialised terms, and, in general terms, non-adapted information (q)

Comprehensiveness of the strategic plans
• Previous training conducted for researchers in co-production and participatory approaches (l)(q) • Lack of leadership, support, and opportunities in the research institution (b)(q) • Logistics and institutional factors: Administrative issues related to workload, allocation of resources (b)(l)(m)(q) Logistical problems in accessing the sample (q) Role conflicts in the same person researching; e.g., clinician and researcher (q) Unaffordable scientific demands such as deadlines, calls, or due dates (m) Lack of financial resources and strong dependency on funds by patients' organisations (l) The emerged topics show that a real concern, knowledge, and interest in the community is important during this phase (l)(p)(q). To plan how to establish trust and rapport with the participants and, if needed, leaders, is key to ensure their short-and medium-term The qualitative data also reflect that during the recruitment, it is essential to clarify how the study meets the community needs and preferences (g)(x), and to ensure the relevance by finding practical applications of the research and/or its outcomes (p)(x), In some cases, health education or enhancement of this type of literacy should be provided (g)(x). Questionnaires and tools, if not standardised, may need to be adapted, including the terms, language, and jargon (g). To facilitate recruitment, the research and co-production process should be designed with individuals in a flexible way, ensuring adaptability of schedules, meetings, questionnaires, and any other research resource. (i)(q).
The improvement of the cultural competencies and openness of the researchers (g)(x) has been mentioned as a requirement. In particular, the study (x) includes the confidence in narratives (of the community members) and the acknowledgement of their contributions. Once more, trust in researchers appears as a key factor (x)(v).
Scepticism and mistrust are significant barriers to accessing the sample (p)(v)(x)(c), and the difficulty for reaching and engaging the right persons for the recruitment (q). However, in early stages, the main barriers are given by individual factors, such as a lack of self-confidence (d)(q), feeling triggered by sensitive issues (i), or being afraid about legal consequences (c). The lack of information fosters distrust and imbalance of power (t). Fear to disclose private information also appears (i) and, from the side of patients or community organisations, fear of worsening the current stigmatisation of some persons (p). Lastly, the distrust in some communities limits the recruitment scope (v). Other barriers to consider, depending on the group/s targeted, are a disproportionate vulnerability to punitive legal/policy consequences (the fear of persecution may prevent persons and groups from participating (c)), the fear of being further demonised or stigmatised (p), or the previous reluctance to seek medical care (g).
Administrative barriers, highlighting the socio-political environment, are based on the conflicts around the definition of the research agenda, appearing early in the design, even during the proposal stages (p)(t): the lack of resources and the excessive workload to meet specific patients' and communities' needs may be an additional source of conflicting agendas (b)(l)(m)(q). These may also prevent the implementation of interventions, programmes, or research projects (b)(l).

Analysis of Engagement and Co-Production Factors
Facilitators and barriers emerging from the texts' interpretation concerning the engagement and co-production processes are summarised in Table 5. Table 5.
Facilitators and barriers during the engagement of participants and the co-production process.

•
Community-researchers attunement: • Communities' factors: Individuals encouraged for engaging in discussions, feeling confident to talk and explain their views (l)(q)(r)(s)(v) (e) Trust and rapport built between communities and researchers/institutions (p)(s)(x)(c) Safety, security, and anonymity (i)(c)(r)(v) Meaningful co-production, used for meeting community goals and needs (g)(p)(q) To feel as being heard, valued, and seen (u) To perceive empathy from the researchers (i) To give participants a sense of responsibility (v) To provide opportunity for producing shifts in thinking (e) To conduct collaborative efforts and deliberations (s) •

Researchers' factors:
Trust and rapport built between communities and researchers/institutions (p)(s)(x)(c) To provide opportunity for producing shifts in thinking (e) To conduct collaborative efforts and deliberations (s)

Logistics and institutional factors:
Organisations committed in their own internal policies to the research and/or the co-production process (  Concerning the key elements found relevant in the analysed papers for the engagement and co-production with vulnerable groups in health research, the most important facilitators were the active involvement of healthcare professionals (j)(p)(q)(r)(s), the early involvement in the process of researching and innovating (p)(q)(s)(x), the community and the leadership's trust in the researchers (c)(o)(p)(r)(t)(v)(x), and the provision of feedback and recognition of the contributors' role, even by acknowledging the co-ownership if possible (l)(s)(u)(v). One of the most important facilitators was to offer a long-term perspective: firstly, by developing community structures, which often involves a meaningful co-ownership (g)(p)(q); secondly, by acknowledging their contributions (l)(s)(u)(v); thirdly, by ensuring financial transparency (m); and fourthly, by offering long-term support by the research entity to the community or advocacy group (l) (p). Another facilitator mentioned was the sensitivity and confidentiality of the process, a requirement to encourage patients to participate in the discussions and feel confident to talk and explain their views (l)(q)(r)(s)(v)(e). To build trust and rapport among participants, community stakeholders, leaders (if any), and researchers is crucial for retaining persons (p)(s)(x)(c).
The researchers cultural and linguistic competencies were also essential. Terms should be adapted during the meetings, as well as in materials, questionnaires, or any other resource provided (l)(p)(x). The researchers characteristics were considered relevant: their expertise, availability, and social skills, as well as the reputation of their institution and the resources available, matter in engaging and co-producing with vulnerable groups in research (p)(v).
Critical barriers also were identified in the qualitative research, with special relevance of the lack of trust in the researcher (c)(o)(p)(r)(t)(v)(x), which might be mutual (c)(o)(p)(t). In addition, tokenism and technocratic approaches appeared to prevent adequate engagement and co-production processes (a)(f)(k)(l)(p)(q)(t). Communication problems were also emphasised in various studies (i)(k)(l)(p)(q). The issues reported included paternalistic communication, and dismission or rejection of experiential knowledge as subjective, private, and irrelevant (k); researchers also might have problems in communicating well with patients, being misunderstood (l). In (p) and (l), jargon and non-emotional communica-tion (e.g., a researcher dispassionately talking about his disease), and feeling ignored or unable to contribute to the project (l), including feeling disqualified and not listened to (q), were addressed.
Again, conflicting agendas between communities, researchers, and/or research institutions also play a limiting role in the successful engagement of communities and vulnerable individuals (k)(o)(p)(f). Moreover, the greater complexity of participative approaches in research, such as the co-production, is seen as a barrier. Finally, an additional barrier for the researchers to implement these approaches was their potential perception of lack of rigour, mainly due to two main pre-conceptions: firstly, the perceived lack of knowledge of the community in the scientific and/or health-specific topic (the community contributors are laypersons) (j)(k)(l)(p); and secondly, the involvement of the vulnerable groups could be understood as a loss of neutrality (p)(q)(s).

Discussion
This study identified several facilitators and barriers when promoting engagement and co-production of vulnerable communities to participate in health research and innovation. Since this study targeted the academic community, the Community-Engaged Dissemination and Implementation (CEDI) framework of domains and competencies [41] was also integrated within the discussion and, most importantly, in the generation of models. Besides, the social determinants of health, as characterised by Dahlgren and Whitehead [16,42], for researching and intervening in the community [42] were taken into account. The consideration of social determinants of health determines a typology and process for tackling social inequalities in health research, care and innovation [28]. Concerning participation, the classic Ladder of Citizen Participation [43] also is integrated jointly with more modern approaches for planning and executing patients and public engagement. Appendix A ( Figure A1). Graphically shows the relations between ladders of participation [43], community engagement, empowerment, and typologies of health research and health interventions in light of health disparities [16,42].
A summary of this meta-synthesis and of the themes that have emerged is presented, aligned with the CEDI model, as well as the main topics of this study: engagement and empowerment through person-centred health research, innovation, and co-production ( Figure 2). In particular, nine domains divided into 40 competencies comprised the CEDI model. These domains were reinterpreted within the most important constructs of this research: relevance (affecting the design and the recruitment and considered from the perspectives of researchers and the views from the communities-five domains), engagement (of communities and/or persons-two domains), and empowerment (which mostly involves co-production with the communities-two domains). Our findings as coded from the papers analysed were discussed accordingly (see Figure 2).
Firstly, concerning the first CEDI domain; i.e., the researchers' attitude towards the community engagement role in research, the analysis revealed the importance of showing sincere concern and interest in the community (p), with an open-minded, interested, and listening attitude shown by the research team (p). Non-participative traditional approaches are still sustained by the academic and healthcare entities involved in research and innovation. Usually, the process of participation is understood as a process of delivering information and then consultation [44], rather than establishing a more profound relationship and engaging in co-production processes. Sometimes, researchers may want too much control without considering the community organisations as co-owners, leading to reluctancy and making it more difficult to reach these traditionally reluctant communities (p). In addition, technocratic approaches and tokenism are barriers to researching the community, even for recruiting persons [44], as seen in (a)(f)(k)(l)(p)(q)(t), since these approaches represent a negative attitude concerning their capacities and/or skills to actively contribute to health research. The extensive training in quantitative analysis and manuscript writing skills dedicated to community members may be a barrier to the implementation of participatory processes in research [45]. In parallel, the researchers' perception of lack of rigour (j)(k)(l) (p) or lack of neutrality (p)(q)(s) in co-production processes were also identified as barriers for engaging communities in research.  Firstly, concerning the first CEDI domain; i.e., the researchers' attitude towards the community engagement role in research, the analysis revealed the importance of showing sincere concern and interest in the community (p), with an open-minded, interested, and listening attitude shown by the research team (p). Non-participative traditional approaches are still sustained by the academic and healthcare entities involved in research and innovation. Usually, the process of participation is understood as a process of delivering information and then consultation [44], rather than establishing a more profound relationship and engaging in co-production processes. Sometimes, researchers may want too much control without considering the community organisations as coowners, leading to reluctancy and making it more difficult to reach these traditionally reluctant communities (p). In addition, technocratic approaches and tokenism are barriers to researching the community, even for recruiting persons [44], as seen in (a)(f)(k)(l)(p)(q)(t), since these approaches represent a negative attitude concerning their capacities and/or skills to actively contribute to health research. The extensive training in quantitative analysis and manuscript writing skills dedicated to community members may be a barrier to the implementation of participatory processes in research [45]. In parallel, the researchers' perception of lack of rigour (j)(k)(l) (p) or lack of neutrality (p)(q)(s) in co-production processes were also identified as barriers for engaging communities in research.
Secondly, the introspection and openness of the researcher-and thus their ability to examine their preconceptions, self-reflection about their own cultural backgrounds, and pre-conceived notions about communities-while practising cultural humility was also found in this meta-synthesis. Community contributors and individuals may struggle in the research and how it potentially contributes to a further stereotyping or marginalisation (p) or even exploitation (t). The marginalisation of experiential knowledge sustained by the participants and community members sustained in the power imbalance must be considered (k)(p)(t). Conflicting realities between communities, even cultures, may arise that also are related to the requirements and duties of all parties involved (m). For instance, communities might not understand the scientific 'rhythms' (m), or culturally and linguistically diverse groups would prefer to engage with a researcher from their own community (o). Structural determinants should be integrated within the research and clinical knowledge, practices, and analysis to avoid revictimization, discrimination, and stigmas. In addition, the 'cultural trauma' could be addressed: analysis should be periodically conducted through multi-disciplinary meetings; the research and clinical staff should be committed and aware of these structural Secondly, the introspection and openness of the researcher-and thus their ability to examine their preconceptions, self-reflection about their own cultural backgrounds, and pre-conceived notions about communities-while practising cultural humility was also found in this meta-synthesis. Community contributors and individuals may struggle in the research and how it potentially contributes to a further stereotyping or marginalisation (p) or even exploitation (t). The marginalisation of experiential knowledge sustained by the participants and community members sustained in the power imbalance must be considered (k)(p)(t). Conflicting realities between communities, even cultures, may arise that also are related to the requirements and duties of all parties involved (m). For instance, communities might not understand the scientific 'rhythms' (m), or culturally and linguistically diverse groups would prefer to engage with a researcher from their own community (o). Structural determinants should be integrated within the research and clinical knowledge, practices, and analysis to avoid revictimization, discrimination, and stigmas. In addition, the 'cultural trauma' could be addressed: analysis should be periodically conducted through multi-disciplinary meetings; the research and clinical staff should be committed and aware of these structural determinants; and the wider community needs to be involved [46]. During the research design phase, the active involvement of individuals and communities led to more relevant objectives and person-centred care, integrated solutions, or, at smaller scales, user-friendly and understandable information, culturally-tailored interactions, or a richer interpretation of data; it may also enhance the dissemination of results [19].
Third, the knowledge of the community is crucial. The relationship with the community and the cultural awareness of the research team are also key elements (q)(s). The participation of a vast range of actors, a real power-sharing collaboration in co-production and partnership, bidirectional learning, inclusion within the research protocol, and intercultural competency, especially for underserved populations [47]. The role of patients and stakeholders seems to be critical for identifying patient-centred research agendas, priorities, inputs on research design, and strategies for increasing the participation and retention in trials [48].
When approaching hard-to-reach, hidden, or disengaged populations, mistrust appears (p)(v). Researchers may need access to a very specific sample through community leaders, who might be fearful of the consequences that giving access may have. There are not universally adopted strategies for recruiting. Most of them are focused on engendering patients and focused on individuals, while researchers working with minorities highlight the importance of involving the community as a whole [49] The level of communitarian disengagement appears in (c)(o)(p)(r)(t)(v)(x). To overcome these difficulties, a collaborative reflection embracing a sense of team ethos and community cohesion is required [5]. However, even when designing and executing a flawless protocol for ensuring co-production and community empowerment, to conduct participatory research does not lead to equal participation and cannot break the power imbalance between community members [19]. Participatory research and, specifically, CBPR is effective: (i) in increasing the participation of racial and ethnic minority subjects in research. It also showed to be a powerful tool for diminishing health disparities, determined by the involvement and the degree of engagement by communities; and (ii) for validating effective interventions among under-represented populations [45].
It is crucial to determine how to keep persons motivated to raise retention and engagement. Motivations should be based on advocacy (q). However, there is a lack of standard reporting guidelines and guidance regarding engagement of stakeholders and patients, as well as information on how to identify and recruit participants [48].
The disconnection between the community and the research entity (m)(p) must be prevented for an effective co-production process, and this is particularly important regarding transparency (p)(t). This disconnection might be produced because researchers or institutions are 'outside of the orbit' of the community, or if a new programme derived from the research is introduced into the quotidian practice of community workers and community boards (p), among other reasons. The recruitment of participants conducted by community members and leaders increases the recruitment rates and the retainment during the participatory research process [45].
Researchers must be willing to share knowledge with the community to learn about the community and the stakeholders involved, mapping representativeness, leaders, relationships, historical events, power dynamics, or customs to perform a realistic needs assessment focused on them and their priorities [44,45,50,51]. This appeared in (l)(p)(q). To know the community by showing real interest is key before selecting which means would work [13]: for instance, knowledge sharing activities with the communities are critical to ensure a truly participatory approach [45,51]. The role of patients and stakeholders seems to be critical for identifying patient-centred research agendas, priorities, and inputs on research design and strategies for increasing the participation and retention in trials [48]. Well-balanced and equalitarian partnerships in research involve users in all stages and focus on experiential knowledge and mutual learning, with openness and respectful attitudes from both sides [52]. Community empowerment may consist of skill-building, priority setting, action plans' strategical design and implementation, evaluation, managing budgets or raising funds, or making local management decisions [50].
At the individual level, to directly appeal to patients' empowerment or participatory methods and co-creation frameworks would help to maximise the recruitment (q)(v).
Fourthly, the appreciation of the communities and individuals' experiences is essential. The fear of further marginalisation appeared in (o)(p)(t), and trust of community key stakeholders and leaders was emphasised in (p)(s)(x)(c). In this concern, negative previous experiences in research have an impact on their attitudes, and therefore in their involvement in research processes (p) The fifth domain is to prepare the researchers-community partnership for a collaborative effort, thereby facilitating dialogue, coordination, and decision making. To integrate the formal and informal processes in the community for decision-making, collaboratively outlining the priorities and obtaining the commitment of organisations and leaders for the co-production process is crucial. These factors were mentioned in (r)(s)(t). Researchers should share results while focusing on contextual issues and avoiding re-stigmatisation of service users (p)(x). Both communities and patients need to be heard, valued, and seen (u). In the case of disengaged and highly stigmatised communities, two additional factors are essential for conducting ethical and safe research: (i) to build rapport; and (ii) to consolidate meaningful and safe relationships with the research team (c). A broad range of parties involved is required, including, but not restricted to, community leaders, advocates, community health workers, individuals, health professionals, public administration officers, and service users (e.g., patients). These groups should be carefully defined before designing the strategy for disseminating and implementing the co-production processes [20,22,47]. Activities for sustaining the community engagement should be demarcated as well, and these should include plans far beyond the mere passive receptiveness of information. It is also crucial to share results and provide relevant outcomes, considering their practical application or their potential for generating new resources in the community studied (g)(p)(x).
The multi-stakeholder approach (l), the need for putting in place formal agreements (m), to raise the potential for dialogue and shifting thinking in all parties involved (e), and collaborative efforts and transparency (m) were confirmed as facilitators of the recruitment in this meta-synthesis. Research showed that the motivation and disposition of community members to take part and engage in participatory processes were personal and professional growth, recognition and respect, sense of ownership and sense of confidence, development of leadership skills, knowledge acquisition, concurrence with prevalent cultural norms, appropriateness of the participatory process with local environment and needs, and perceived or experienced beneficial outcomes [50].
The co-production can minimise the power imbalances between researchers, communities, and institutions [44,48,50], as shown in (p)(r)(s)(t). The engagement and outcomes related to participation seemed to be greater for researchers willing to conduct their studies under a multi-disciplinary approach (s). This implied sharing results as soon as possible with community members (p)(r)(t) and providing ownership to communities themselves (r)(t).
All these factors under the fifth domain were also related to the sixth domain, which is the collaborative planning for the research design and goals. The involvement of the populations in the design phase [44,48] since the early beginning (l)(p)(q), as well as the importance of a jointly defined research agenda, were key facilitators (k)(o)(p)(f).
Seventh, the communication effectiveness is related to a clear presentation of ideas, listening attitude, and culturally sensitive and plain language. Our research showed the importance of the information being specifically prepared for the community, culturally tailored, from the design phase (l)(m)(q)(s)(t), using adequate terms (g)(p)(q); and how unclear information (t), jargon (q), or language barriers are problematic in these participative research processes. In sum, communication problems appeared as major barriers for researching involving vulnerable persons (i)(k)(l)(p)(q). Thus, sensitive communication when addressing the problems faced by participants and/or by communities is needed: communication problems in this regard arose as an important barrier [44].
The eighth factor is the equitable distribution of resources and credit, including financial resources, resource distribution, and role in media coverage and scientific publications. Planning how to share results (p)(r)(t) and provide ownership (l)(r)(s)(t)(u)(v) appeared. In addition, budget and resources were mentioned (r)(e), as well as financial transparency (m). In this regard, it is worth mentioning that collection, interpretation, and exchange and co-ownership of data are very complex issues that could be discussed in terms of the consequences of these processes for the groups themselves. Data gathering may be detrimental to deprived or marginalised communities. Besides, the indicators may be culturally inadequate, the stakeholders may be under-represented or disregarded, and the results are sometimes inaccessible for them [15,27].
Lastly, the ninth domain is the long-term relationship, sustaining the partnership and integrating the capacity building, the long-term funding, the self-sustainability of research and healthcare innovation projects and programmes, and the commitment of devoting time and efforts to addressing stakeholder needs beyond the research [52]. Long-term financial and organisational support (l)(p) appeared jointly with results sharing (q)(s)(t). Both factors seem to be linked to the dependency on funds by patient organisations (l) and the lack of long-term engagement of researchers perceived by the community (m). Organisational commitment and policies, budget, resources, time, and training (r)(e) are important for preventing a negative sense of exploitation (p)(t)(x) or abandonment (o). To overcome these difficulties and perceptions, structures to sustain the communities' empowerment in the long-term could be provided (g)(p)(x) while also considering the sharing of resources (p)(t) and raising policies and organisational commitment for ensuring the persons' participation (r)(e).
The goal of our study was to provide sound knowledge for research into personcentred care by empowering deprived communities to be part of research and innovation in health and social care. To achieve this empowerment, we must integrate the lessons learned and the findings exposed in these results, as well as the ladders of participation [43] and the typology of actions on health inequalities [42].

Implications for Practice
The implementation of co-production methods during the entire research process could offer a more tailored process and a more successful recruitment, raising the recruitment and retainment of traditionally disengaged communities. It is needed to engage participants, advocacy entities, and groups in the long term.
The checklist in Figure 3 summarises our findings translated into best practices, divided into the phases of the design and execution of a person-centred co-production.  On the one hand, at the individual level, to offer flexibility and to foster self-efficacy to ensure safety and confidentiality are key aspects. During the co-production, to engage participants, raise their confidence, adapt terms, and overcome the tokenism are essential to empowering vulnerable persons. Likewise, to prepare appropriate information addressed at individuals and communities to be involved, founded on a sound knowledge of the community, is needed. On the other hand, at the community level, it is required to consider the disengagement, the need for structures, and long-term alliances to empower communities at practical and real levels. Vital factors include tackling the power imbalance during the early stages, involving health professionals and key stakeholders during the execution of co-creation processes, and building trust. Trust and acknowledgement of community contributors are decisive during the design and recruitment stages, as well as during the execution phases. The acknowledgement of their contributions, even co-ownership (whenever possible or pertinent), should be considered. The role of the research and the co-production for studied communities depends on their capacity to produce a real and long-term change that translates into meaningful empowerment of persons and communities, therefore paving the way to more efficient person-centred care. There are some important considerations when fostering personcentred care through the engagement and empowerment of individuals and communities.
On the one hand, at the individual level, to offer flexibility and to foster self-efficacy to ensure safety and confidentiality are key aspects. During the co-production, to engage participants, raise their confidence, adapt terms, and overcome the tokenism are essential to empowering vulnerable persons. Likewise, to prepare appropriate information addressed at individuals and communities to be involved, founded on a sound knowledge of the community, is needed. On the other hand, at the community level, it is required to consider the disengagement, the need for structures, and long-term alliances to empower communities at practical and real levels. Vital factors include tackling the power imbalance during the early stages, involving health professionals and key stakeholders during the execution of co-creation processes, and building trust. Trust and acknowledgement of community contributors are decisive during the design and recruitment stages, as well as during the execution phases. The acknowledgement of their contributions, even coownership (whenever possible or pertinent), should be considered.

Limitations and Strengths
The great amount of literature reviewed, together with the qualitative perspective selected to analyse the discourse of key persons involved in the research, constituted a strength of the current research. Qualitative research allowed us to obtain a vast range of information about the participants' perspectives, solutions proposed, assumptions, beliefs, strengths, and structural problems in their own terms, which is crucial for designing well-tailored interventions attending to the targeted audiences' narratives. Likewise, the integrative perspective and the focus on the individuals' agency and the community empowerment for focusing the engagement was a meaningful strength of our study. The innovative methodology for analysing a vast amount of data through the integration of grounded theory principles were used, although the general structure was a meta-synthesis due to the huge number of papers and dissertations (102 in total; 23 of them were included in this study) included in the general dissertation. The innovative approach allowed us not to lose important information by: (i) facilitating the extraction of key thematic areas arising from the information; and (ii) not attaching to a single framework (e.g., the CEDI) delimiting the codes and the analysis of the information, but facilitating the comparison and the analysis with the literature.
The study also had some limitations that relied on the non-exhaustiveness of the literature sample included. As a matter of fact, this research was a part of a larger metasynthesis not entirely focused on research and co-production, but strongly linked to these topics. Conversely, the 'partial' nature ensured its integration into a wider frame, joining key themes on health communication and patient and community participation: decision making, self-management of health, or counselling were jointly treated in a comprehensive viewpoint, which supposed a great added value in terms of integrative perspectives able to inform practice.
Further research will be conducted on the prioritisation of factors and on the validation of the checklist and best practices extracted. The outputs will be tested in real research settings through qualitative research to validate and prioritise those that would be specifically needed for person-centred care. The research results will be disseminated to health and social care professional and workers in plain language.

Conclusions
This qualitative study reviewed and showed the experiences of researchers, patients, and communities, as well as other relevant stakeholders, such as public administration officers. The knowledge captured in these experiences allowed us to identify facilitators and barriers, as well as provide best practices for conducting a culturally tailored and empowering co-production in research and healthcare innovation. Three challenges were addressed in the study design: (i) how to raise the recruitment of the disengaged; (ii) the potential for empowering persons and communities through research and/or co-production; and (iii) the engagement of deprived and disengaged groups in light of the social determinants of health. The co-production during all research phases offered a well-tailored process, and successful recruitment of participants and key stakeholders. The safety of the participants, the confidentiality of the information, and the awareness of power imbalances-both between researchers and communities and among participants-during the research was critical from the point of view of the effectiveness, engagement, and ethics of the study during its entire lifecycle. When designing innovation and/or interventions involving vulnerable communities, socio-economic and cultural settings and systemic co-determinants should be integrated within the co-production process. Collective empowerment depends on the access to basic services (among others, healthcare) and the material circumstances, equitable societal structures (policies, budget and funds, and approach and focus of the measures undertaken by decision makers), and structural determinants (again, socio-economic, cultural, and environmental conditions co-determining health inequalities at a macro level). Co-production processes could be approached for raising the individuals self-efficacy, skills, and access to services; the advocacy capacities of the community and civil society players; and for supporting long-term changes and promoting healthier policies able to change current vicious cycles of poverty and poor health outcomes. To collaborate with communities and to sustain or, at least, not interfere in the creation of sustainable structures and bonds will result in meaningful empowerment and an enhanced sense of agency of all participants. Funding: These results are part of wider research supported by the regional government through the Valencia Agency of Innovation (AVI) under grant INNTAL31/19/001, project COMSALUD (estrategias de alto impacto en COMunicación de la SALUD e implementación de proyectos socio-sanitarios con grupos psicosocialmente vulnerables-High-impact strategies in health communication and in implementing socially relevant health interventions with psycho-social vulnerable groups).

Institutional Review Board Statement:
This research was a review article and did not involve human and/or animal subjects. The study was conducted ethically and responsibly in full compliance with the eligible standards of integrity and relevance of the research and, specifically for review works, acknowledgement of all primary sources consulted and revised.