Nursing Care Coordination for Patients with Complex Needs in Primary Healthcare: A Scoping Review

Introduction: Millions of people worldwide have complex health and social care needs. Care coordination for these patients is a core dimension of integrated care and a key responsibility for primary healthcare. Registered nurses play a substantial role in care coordination. This review draws on previous theoretical work and provides a synthesis of care coordination interventions as operationalized by nurses for complex patient populations in primary healthcare. Methodology: We followed Arksey and O’Malley’s methodological framework for scoping reviews. We carried out a systematic search across CINAHL, MEDLINE, Scopus and ProQuest. Only empirical studies were included. We performed a thematic analysis using deductive (the American Nurses Association Framework) and inductive approaches. Findings were discussed with a group of experts. Results: Thirty-four articles were included in the synthesis. Overall, nursing care coordination activities were synthesized into three categories: those targeting the patient, family and caregivers; those targeting health and social care teams; and those bringing together patients and professionals. Interpersonal communication and information transfer emerged as cross-cutting activities that support every other activity. Our results also brought to light the nurses’ contribution to care coordination efforts for patients with complex needs as well as critical components that should be present in every care coordination intervention for this clientele. These include an increased intensity and frequency of activities, relational continuity of care, and home visits. Conclusion: With the growing complexity of patient’s needs, efforts must be directed towards enabling the primary healthcare level to effectively play its substantial role in care coordination. This includes finding primary care employment models that would facilitate multidisciplinary teamwork and the delivery of integrated care, and guarantee the delivery of intensive yet efficient coordinated care.


INTRODUCTION
Over the last two decades, integration has become a major concern for many governments and healthcare systems [1][2][3][4]. With limited financial resources, aging populations, and comorbid chronic diseases [5][6][7], many countries have recognized the need to move from fragmented and discontinued care towards a more integrated healthcare system [8]. Studies showed the potential of integrated care to improve continuity of care, accessibility, quality and safety of care, as well as cost effectiveness of services [9]. Care coordination around patients' needs has been acknowledged as a core dimension of integration that facilitates the provision of comprehensive and seamless care [10]. It has also been recognized as a key responsibility for primary healthcare [11].
As complexity grows, so does the need for a stronger primary healthcare able to deliver more care in the community and coordinate care within primary care and across care levels [12,13]. Millions of people worldwide have complex needs that span beyond what the healthcare system typically provides [14]. Fragmentation of health and social care services causes patients with complex needs to bear the major responsibility for navigating their own pathway through services and providers [15] and they experience systems as being confusing and overwhelming [16]. For these patients, care coordination and integration of health and social care services are even more relevant.
Although the aim of care coordination is widely agreed upon, there is still a lack of global consensus around a single conceptual model and much ambiguity in the definitions of care coordination [17]. The Agency for Healthcare Research and Quality defines care coordination as "the deliberate organization of patient care activities between two or more participants (including the patient) involved in a patient's care to facilitate the appropriate delivery of health care services" [18]. A variety of approaches has been adopted to deliver coordinated care in practice. Case management is perhaps the most intensive intervention for caring for people with complex health and social needs [19]. Case management has been established as a targeted, community-based and proactive approach to care that involves case finding, assessment, care planning, and care coordination [19]. Patient navigation is another approach that has emerged within primary care as a means to link patients and families to primary care services, specialist care, and community-based health and social services to provide holistic patient-centred care [20]. The Agency for Healthcare Research and Quality has identified several other approaches and terms that are often used synonymously or in conjunction with care coordination, namely collaborative care, disease management, care management, and the Chronic Care Model [18].
However, irrespective of the approach that is adopted, an essential dimension of effective care coordination is the involvement of a multidisciplinary primary care team that functions as a cooperative, cohesive unit to provide the right care in the right place at the right time [16].
Within primary healthcare, the role of care coordinator can be undertaken by professionals who come from various backgrounds, including nursing, social work, physiotherapy and occupational therapy, as long as they are equipped with and trained on the necessary skills [19]. The choice of a designated care coordinator is often dependent on contextual factors, the population of interest, and the goals of the program. Indeed, a foundational element of care coordination is a holistic care perspective that includes addressing clinical/ medical as well as the broader determinants of health [21]. It is this very perspective that gave both nurses and social workers their legitimate position in organizing and managing care for a complex population. However, one might be better equipped than the other depending on the patient's condition and the disciplinary expertise this condition primarily calls for. For instance, social care expertise is particularly important for patients in the rehabilitation and reablement phases and those with a functional decline [19], while nursing clinical expertise may be more relevant for patients suffering from serious pathologies such as cancer [22]. In either case, health and social care professionals still have to work collaboratively and use their unique skills and disciplinary expertise as needed. Primary care practices that have the capacity (e.g. structure, resources) have implemented a team-based model of care coordination where the social worker and registered nurse carry out a joint patient assessment. This care coordination model proved effective in increasing communication between health and social services and in improving care for complex patients such as older health consumers [23].
This scoping review focuses on the role of registered nurses in care coordination. Nurse-led care coordination interventions proved effective in improving access to appropriate treatment [24]; reducing costs [25][26][27]; improving clinical outcomes [27,28] and quality of care [29]; improving communication between staff [30]; increasing safety of vulnerable patients during transition [29]; and reducing their unplanned readmissions [19,31]. It should be noted that, depending on local needs and resources, nurses might be employed to undertake exclusive care coordination activities [32,33] or they might combine care coordination with wider team management responsibilities or with clinical care provision [34].
Despite the substantial involvement of nurses in care coordination efforts, their contribution still has to be clearly "defined, measured and reported to ensure appropriate financial and systemic incentives for the professional care coordination role" [35].
To date, there persists a lack of knowledge about interventions and activities performed by registered nurses for patients with complex health and social care needs in primary healthcare. An in-depth analysis of how the nursing care coordination role for patients with complex needs is operationalized is clearly needed. The Agency for Healthcare Research and Quality also stressed the need for care coordination frameworks to be enriched by empirical data. In 2010, the Agency developed a framework and specified that "this framework provides a starting place for understanding care coordination… and is intended to grow with the field… since care coordination is a rapidly growing evidence base field" [36].

AIM AND RESEARCH QUESTIONS
This scoping review draws on previous theoretical work and aims to provide a synthesis of care coordination interventions as operationalized by nurses for patients with complex health and social care needs in primary healthcare. Our research questions are: What care coordination interventions are currently performed by registered nurses in primary healthcare? Who are the target complex patient populations? What activities do these interventions involve?

CONCEPTUAL FRAMEWORK
In 2013, the American Nurses Association developed a framework for measuring nurses' contributions to care coordination [37]. This framework was based on several other theoretical frameworks including the one developed by the Agency for Healthcare Research and Quality for healthcare. The American Nurses Association's framework has the strength of providing a roadmap for how conceptualization of nursing's role in care coordination can be operationalized, quantified and measured, and includes thirteen constructs that comprise the nursing care coordination processes. Thus, we considered it a particularly suitable starting point for our review. However, care coordination activities described in the American Nurses Association Framework were cross-cutting, relevant to all settings of care and services, while we were specifically interested in the primary healthcare level and target complex patient populations.

METHODS
We followed the methodology proposed by Arksey and O'Malley [38] and further developed by Levac et al. [39]. This methodological framework offers six stages for carrying out scoping reviews: Identifying the research question; Identifying relevant studies; Selecting studies; Charting the data; Collating, summarizing, and reporting the results; Consulting experts.
1. Identifying the research questions (that we mentioned above).

Identifying relevant studies:
We performed a literature search using the many terms that were identified by the Agency for Healthcare Research and Quality to describe care coordination interventions: "care coordination; case management; disease management; care management; care navigation; patient navigation; patient-centred medical home; and integrated care". We combined these terms with "primary healthcare" or "primary care" and "nurses". The search strategy, developed in consultation with an experienced medical librarian, may be found in Appendix 1. We conducted our search across the following databases: CINAHL, MEDLINE, Scopus, and ProQuest (dissertations and theses), for articles published over the past 15 years (between 2004 and 2019).

Study selection:
In order to be included, articles had to report on an empirical study describing a nurse-led care coordination intervention in primary health care for adult patients with complex needs. Articles had to be written in English or French. Articles that described an advanced nursing practice, or a specialized (hospital, emergency department) level of care-based intervention were excluded. Articles were also excluded if the nurses activities and their distinct role within the multidisciplinary team were poorly described. No restrictions were set in relation to the nurses' employment arrangement. Two independent reviewers (MK and NG) assessed the selected abstracts for inclusion. Disagreements were resolved by a consensus-based discussion between both investigators, or by a third reviewer (CH). For the purpose of this selection, we had to clarify what we mean by "patients with complex health and social care needs". In the light of an extensive review of the existing literature on the subject, we put together a series of six areas of "vulnerability", the combination of which define complex needs (Figure 1). Consequently, we adapted Kuluski's definition of complex needs [14] as follows: "Complex health and social care needs result from multiple concurrent chronic conditions, functional and cognitive impairments, mental health challenges and social vulnerability, the individual's characteristics, or a major change in his life or care trajectory". Patients presenting either a combination of two or more elements, or a major vulnerability in one of these six areas (i.e. severe mental illness; transition to palliative stage) were considered as having complex needs. Very often, this combination of multiple elements (i.e. chronic conditions and social, mental health, and economic stressors) contributes to increased care utilization [40], therefore high-cost patients and frequent users were also included in our synthesis. 4. Charting the data: Two authors (MK and NG) extracted the following variables from each selected article: the study design, objectives, care coordination intervention, target population, and context. Care coordination activities were examined and extracted according to the American Nurses Association Framework for measuring nurses' contributions to care coordination [37].

Collating, summarizing and reporting the results:
We performed a thematic analysis using both deductive (using the American Nurses Association Framework) and inductive approaches. We used an initial list of predefined codes but also identified emergent codes through repeated examination of each care coordination intervention. We then identified patterns and relationships in order to organize codes into interrelated categories, then summarized the data [41]. Codes and categories were constantly discussed between investigators and evolved throughout the analysis phase. NVivo 12 software was used for data organization and management. 6. Consultation: Preliminary findings were presented and discussed on two separate occasions with senior and junior researchers in the field of integrated care during a face-to-face scientific meeting and a live videoconference. The latter also included a patient-research-partner. Researchers had a range of expertise (in nursing science, general medicine, mental health, social work and anthropology) and helped to refine the results and validate the implications for future research and practice.

RESULTS
Two hundred and thirteen full-text articles were screened; 34 articles met the inclusion criteria and were included in the synthesis. Our search results and the retrieval and selection of studies are presented in the flow diagram below (Figure 2). The 34 studies included in our synthesis reported on 26 different interventions. When the same care coordination intervention was reported in several articles, only the paper that provided a full description of this intervention was coded. However, the content of these other papers contributed to the consolidation and further clarification of the extracted data. Table 1 presents all included papers, their main features and results.

COMPLEX TARGET PATIENT POPULATIONS
The target patient populations identified in the included studies were also diverse. We have gathered them into seven categories according to their common areas of vulnerability as presented in the "Complex health and social care needs" model (Figure 1) above, as well as their frequent use of health care services.

CARE COORDINATION ACTIVITIES
In addition to the variations in care coordination activities within the same type of intervention, we noted a variation when we tried to compare care coordination activities according to target patient populations. For instance, within the category of older patients with multiple vulnerabilities and significant use of healthcare services (category 4), facilitating care transitions was not mentioned in all studies, although present in several studies [32,50,56,60]. We were able to synthesize overall nursing care coordination activities into three categories: activities targeting the patient, family and caregivers; those targeting health and social care professionals and services; and those bringing together patient and professionals. One last category was found to be crosscutting, supporting and enhancing every other activity, namely interpersonal communication and information   (Figure 3). In the following section, we present the four categories and their respective activities; a more detailed description of these activities is provided in Appendix 2.  [46,51,57,66]. It is reviewed and updated as needed [49,50,58,68,71]. In some cases, it is written in lay language and

Patients with severe mental illness
Patients with moderate to severe depression [43,52] 2. Patients with common or severe mental illness + chronic condition(s) Adults with severe and persistent mental illness who had developed type II diabetes [55] Patients with poorly controlled diabetes mellitus, coronary heart disease or both and comorbid depression [53] Patients aged 60 years and over with depression and osteoarthritis pain [58] 3. Patients with social vulnerability + chronic condition Low-income, ethnically diverse populations at elevated risk of cardiovascular disease events, including those with existing coronary heart disease or diabetes [44] Diabetic patients at high risk for complications, in an underserved Hispanic population [45] Underserved, uninsured community with type II diabetes [70] 4. Older people with physical, cognitive, psychosocial or psychiatric vulnerabilities (+ significant healthcare use) Community-dwelling frail people aged 60 and older [72] Community-dwelling frail older people (> 70 years) [49,51] Patients aged 70 years and over at increased risk of functional decline [71] Frail persons aged 65 years and over at increased risk of functional decline [68] Older patients with multimorbidity and functional disability and who had generated high insurance expenditures for health care [32] Community dwelling older people with disabilities and recent significant health care utilization [60] High risk patients with disability (or their caregiver) and recent significant (or expected) health care utilization [59] The most vulnerable older adults (based on patient's categories of diagnoses and disease severity to predict medical expenditures) [56] Chronically ill community dwelling older people at high-risk for mortality, functional decline, or increased health services use [50] 5. Old age people + chronic condition(s) Older people with chronic and complex illness who are at risk of further exacerbation and/or hospitalisation [66] 65 years of age and older with multimorbidity [33] Community-dwelling older adults with dementia symptoms and their informal caregivers [47] Patients aged 70 years and over, living at home, and diagnosed as having dementia [57] Older people with chronic conditions [48] 6. Patients living a transition to end-of life/ palliative stage Patients with varying stages of cancer progression [61,69] 7. High costs and frequent users of health care services Frequent users of healthcare services who had chronic diseases [46]  displayed prominently in the patient's home [32]. Finally, as part of this care planning, nurses educated the patient about the care coordination efforts being made to improve their quality of care and what the patient's responsibilities were [70]. -Provide care directly: nurses follow explicit guidelines and protocols for disease risk reduction [44], and conduct health status and physiologic monitoring (i.e. blood pressure and blood glucose) [44,74]. Other nursing tasks include carrying out basic screening (i.e. cancer screening) and managing symptoms as well as episodic illness and concurrent chronic diseases [61]. -Monitor, follow up, and respond to change: monitoring includes symptoms, clinical results, current medications, errors or omissions, adverse effects, and adherence to therapeutic plan [32, 33, 43, 45, 47, 48, 50-53, 57-59, 68, 71, 72]; but also, emergency department visits, hospital admissions, or any other encounters that would change the risk status and trigger an intervention [48,50]. -Establish relational continuity of care by building an ongoing, personal and meaningful relationship of mutual trust with the patient over time [46,50,61,66,69,70], advocating for them [69], and serving as their main point of contact and their "go to" person at all times [32,34,45,47,61,66,67,69].
-Plan end of life care: nurses identify the presence of advance directives, inform the patient regarding their right to state their preferences for care at the end of life, and assist the patient and family with planning end of life options [33]. They also provide ongoing emotional support to the patient and family [61]. -Supporting patient activation, engagement and empowerment requires a collaborative relationship between nurses and patients and their families, the involvement of the entire care team in planning, carrying out, and following up on patient care, and planning a coherent and continuous set of support methods [69]. These activities include enabling patients to be involved in treatment and diagnostic choices, to collaborate with providers, and to navigate the healthcare system and community resources [75][76][77].
Thus, they are embedded in many of the other activities described earlier, such as assessing patients' individual needs and goals, facilitating their participation in care, involving them in the development of their own care plan, serving as their main point of contact and advocating for them, and helping them state their individual preferences for care at the end of life. Patients' activation and empowerment also include linking patients with health and social care teams in order to enable engaged participation and shared decision-making as described further below.
These activities are not sequential but rather iterative. Typically, a comprehensive assessment is needed in order to identify patients who would benefit from a care coordination intervention; in turn, patients identified as target beneficiaries require a comprehensive assessment of their needs and goals in order to develop their care plan. Finally, we were able to identify three main features of the activities targeting the patient and family: 1) they may occur during home visits; 2) they are undertaken in close collaboration with the general practitioner and health and social care teams. This is particularly relevant when targeting eligible patients and care planning; 3) they are complementary to and do not replace the general practitioner's activities. Nurses organized care that the general practitioner was not able to organize due to lack of time or because they did not have the knowledge of services available [51,66,67], and seemed to be very effective in areas that are less extensively addressed by the general practitioner such as complex assessments of function and social support [56] or self-management support [54]. Overall, collaboration between nurses and general practitioners resulted in a broader assessment of a patient's health and the development of more comprehensive care plans [50] thus, improving health management.
Care coordination activities targeting health and social care professionals and services -Clarify roles, negotiate responsibilities and establish shared accountability: care coordinator nurses explain their role to other professionals [32,51] and, through the development of the care plan, discuss and specify all actions expected from each participant and discipline [51,57,71]. They ensure accountability by systematically reviewing and discussing cases with the general practitioner and other team members, and jointly deciding on appropriate actions to take [32,33,[51][52][53]57]. -Exercise leadership: nurses build relationships and personal credibility with other professionals [55]. They provide local knowledge and a single point of contact and a familiar face for health and social care providers [66,67]. They serve as a resource to the team [55,70] and facilitate the implementation of an interdisciplinary care approach with their organizational and communication skills and empathic capacity [51,67].
Care coordination activities that link the patient and family with health and social care professionals and services -Link and partner with community resources (outside the healthcare system): nurses coordinate, arrange and monitor access to community resources and social care tailored to patients' specific needs (i.e. public housing, meal services, financial assistance services, smoking cessation, self-management support course led by trained lay people, etc.) [32,33,44,46,48,50,60,61,66,69,72]. They also provide a guidebook with available social and welfare services [47]. -Link and partner within and across multidisciplinary healthcare teams. This includes: • coordinating patient care with the general practitioner and other healthcare professionals [32-34, 43, 45-48, 50, 51, 55, 56, 58, 71]; • organizing case review sessions and team meetings to discuss patient specific situations and innovations in care [49,50,52,53,55,57,66,68], communicate changes in treatment plan, discuss medication management [33,48,49,60], or discuss questions the patient had but were uncomfortable to ask to their general practitioner [50]; • organizing general practitioner-patient-familynurse meetings to facilitate communication [59,60]; • linking patients to their general practitioner and specialists [32,33,44,46,47,55,69]; • assisting patients in preparing their appointments with their general practitioner [48]; • organizing referrals to specialty services when needed [43-45, 47, 48, 69-71]; and • training patients on how to identify and navigate the healthcare system [48]. -Facilitate care transitions consists of smoothing the patient's path between all services and care providers with a focus on transitions through hospitals [32,33,56,60,61]. Care coordinator nurses coordinate with but do not replace the hospital discharge planning professionals and provide them with information on home environment and safety and any caregiver issues that may affect discharge planning [48]. Nurses perform ongoing monitoring and assessment tasks during transitions [50], adjust patient care plans to meet current needs [33,50] and keep the general practitioner informed of the patient's current status [32].

Cross-cutting activities related to interpersonal communication and information transfer
-Engage in open and honest communication with patients about their health and social situation: honest communication seems to support every other activity with the patient and family, starting with a comprehensive assessment of their needs and goals [46], the discussion of questions that they were uncomfortable asking their general practitioner (linking them with other professionals) [50], and the establishment of relational continuity that fosters a trusting and meaningful relationship [67]. -Engage in interpersonal communication with health and social care professionals: again, every single activity that nurses undertake with and for professionals seems to be supported by interpersonal communication. This is particularly relevant to clarifying roles and responsibilities [32,51,71], establishing shared accountability [32,33,[50][51][52][53]57], providing local knowledge [47] and facilitating the implementation of an interdisciplinary care approach [51,67,70]. -Transfer information: nurse care coordinators communicate care plan letters and other relevant information to patients and families [33,50]. They transfer information to the general practitioner and other health service providers about issues identified in the screening, treatment, service provided to the patient, clinical evolution, etc. [43,46,48,50,51,57,60,66]. They also document this information and provide timely updates [32,33,43,46,47,49,66,68,70].

DISCUSSION
Nurses are playing an increasingly central role in care coordination. However, no previous model has provided an in-depth analysis of this role for patients with complex health and social care needs in primary care. Our conceptual framework of care coordination provides an extensive description of each care coordination activity (or domain). This new information could constitute a valuable contribution that facilitates the design and implementation of care coordination interventions for patients with complex needs. Furthermore, our synthesis of care coordination interventions is based on empirical studies and with a focus on the way these interventions are operationalized. We propose a pragmatic model of care coordination for patients with complex needs that would be close to the field reality of health and social care professionals.

SUMMARY OF FINDINGS
Our results showed the multitude of interventions used to coordinate care around patients with complex health and social care needs in primary health care. This heterogeneity was expected and confirms the fact that care coordination can be operationalized in different ways. Care coordination interventions also differ on the basis of their context, the population of interest, and the goals of the program [78].
The care coordination model that we propose should not be regarded as a manual to be followed but rather as a tool to guide professionals and decision makers tailoring their own intervention based on the needs of their target patient population as well as their contextual and environmental realities. The success and failure of integrated care interventions, including care coordination, have always been context dependent [79,80].
Our findings also confirmed the fact that the care coordination role may be undertaken exclusively or combined with other primary care duties. In fact, nurses seem to perform the same care coordination activities independently of their employment arrangement. We hypothesize, though, that what may be different is the caseload of nurses and, again, the intensity of their support. Goodman (2010) showed that exclusive case managers provided greater input to their patients and higher contact time per month than did nurses who undertook other duties concurrently [81]. However, the authors also pointed out the increased cost of exclusive case management. Therefore, healthcare organizations are faced with the challenge of finding employment models that can ensure balance between efficiency and intensive care coordination for target patient populations or individuals.
This review shed light on critical components of care coordination that are specific to patients with complex needs. Firstly, although the care coordination model may seem to include the same activities for patients with long-term conditions without particular complexity, the main difference is the greater frequency and intensity of activities when caring for patients with complex needs. Several studies highlighted the need for care coordination to be targeted according to the varying intensity of needs [19,81]. Leutz (1999) and Kodner (2002) addressed the question of "who needs what level of integration" [82,83]. The authors suggested that different levels of integration should exist for patients according to their needs, their capacity for self-direction, and the specific challenges they face in obtaining appropriate care [82]. Our findings illustrate how complex patient groups would require a broader span, more intense, and more thoroughgoing interventions. Garcia et al. (2018) conceptualized a spectrum of care management need that ranges from complex patients who have sufficient skills and resources thus "not needing intensive care management" to "patients needing more than intensive care management" [40]. For the first group, patient navigation, a less intensive intervention, may address their needs effectively by reducing barriers and bridging gaps in service [84]. The patient navigation role may indeed be played by nurses and social workers or by lay persons trained adequately [85]. Patients at the other end of the spectrum are those requiring more specialized interventions beyond those offered by care management [40]. Between these two extremes of the spectrum, there are the patient populations identified in our review and for whom a comprehensive, intensive care coordination intervention, by a professional, is necessary. In fact, the included studies described patient navigation as one component of a wider intervention.
Primary care registered nurses provide a broad range of services for patients with long-term conditions without particular complexity. These include chronic disease prevention and management, medication management, health education and therapeutic interventions [86]. These activities seem to be very present when coordinating care for patients with complex needs. Indeed, our findings highlighted activities related to their clinical skills such as conducting a comprehensive assessment including for medical needs and goals; careful monitoring of patient symptoms; early identification of exacerbations; medication reconciliation and early identification of adverse effects; providing patient education that includes self-management of their medical conditions and recognizing alarming symptoms, as well as providing direct evidence-based care. Previous results indicate that when nurses are an integral part of direct care through the management of the interdisciplinary team, programs have a great opportunity to improve quality of care and clinical outcomes, and reduce beneficiaries' need for hospitalization [87,88].
Secondly, the establishment of a relational continuity of care with the patient and family also emerged as a critical component of care coordination for patients with complex needs. In addition to the intensity of support, our results emphasize the availability of the care coordinator out of hours and when urgent issues arise, which leads to the development of a great relational continuity of care. In fact, for patients with complex needs, integrated care often means a single point of entry and a personal contact with a designated care coordinator [89]. Our findings show how nurses become patients' "go to" person at all times. Studies showed that relational continuity improved preventive care, reduced hospitalization, enhanced adherence to treatment, and increased satisfaction with care [90,91].
Finally, home visits seem to be particularly important when coordinating the care of patients with particular needs or certain complex needs. This is mainly in response to the target patient populations' vulnerability and sometimes functional decline [92], but also because it allows nurses to gain more insight into the patient's living environment, including safety issues [33,48] and caregiver burden [93], which are crucial to care planning. Nevertheless, home visits should not be regarded as an isolated activity, but rather as a feature of a comprehensive care coordination intervention whose first step is to know the patient and caregiver in order to identify what care or service they need [94].

IMPLICATIONS OF THE RESULTS ON RESEARCH AND PRACTICE
It is widely recognized that complex interventions are often not delivered or adhered to as intended [49]. Yet, studies included in our review rarely reported on their assessment of intervention fidelity. Furthermore, we do not know if nurses performed one activity more than another, or whether they needed capacity building for the least performed activities. Future research should address these two areas since answers might explain, at least partly, the limited efficacy of some interventions.
Also, it would be interesting to attempt and establish a classification of activities according to their value, i.e. efficacy versus time and resource consumption.
Our scoping review did not aim to compare the nurses' role in care coordination to that of another professional. Future research could highlight the specificity of each professional and their added value in the coordination of care.
In practice, the co-location of health and social care professionals has gained considerable attention over the last few years for what it offers in terms of facilitating multidisciplinary teamwork and the delivery of integrated care [81]. Our findings reaffirm the fact that no single professional has the ability to complete the task independently, and that "close" collaboration between health and social care services is particularly important for eff ective care coordination. This review could therefore constitute an additional argument in favour of the staff co-location.
Finally, recognizing care coordination in practice requires defining the work and purposefully examining when, where and how it is happening [87]. This synthesis would support the development of a system to document nurses' care coordination activities as a way of ensuring appropriate financial and societal recognition of their contribution to high quality, efficient and integrated care.

STRENGTHS AND LIMITATIONS
To our knowledge, this is the first study to synthesize nursing care coordination activities for patients with complex needs in primary healthcare. We were able to propose an exhaustive model of care coordination, as well as a comprehensive description of patients' complex health and social care needs. Another major strength would be the validation of our findings by a patient-research-partner.
As for limitations, this scoping review did not provide a comparison between care coordination interventions or their efficacy. The complexity and heterogeneity of interventions represent a real challenge for comparison and necessitate the use of research designs other than a scoping review. Another limitation could be related to the fact that our findings are based on the description of activities as provided in included studies. These descriptions were sometimes poor or lacked important elements, so we may have missed details or features of some activities. However, to mitigate the missing information, we examined all articles reporting on the same intervention.

CONCLUSION
A multitude of interventions are used to coordinate the care of patients with complex health and social care needs in primary health care. Despite this heterogeneity, they share a commonality in that they involve a great frequency and intensity of care coordination activities related to the complex needs of the target patient populations. Care coordinators establish a great continuity of care with these patients due to their availability outside of regular hours and when urgent issues arise. As complexity grows, efforts must be directed towards enabling the primary healthcare level to effectively play its substantial role in care coordination. This includes finding primary care employment models that would facilitate multidisciplinary teamwork and the delivery of integrated care, and guarantee the delivery of intensive yet efficient coordinated care.

ADDITIONAL FILES
The additional files for this article can be found as follows: