Indicators of home-based hospitalization model and strategies for its implementation: a systematic review of reviews

Background Home-based hospitalization (HBH) offers an alternative delivery model to hospital care. There has been a remarkable increase in pilot initiatives and deployment of this model to optimize services offered to a population with a variety of progressive and chronic diseases. Our objectives were to systematically summarize the indicators of HBH as well as the factors associated with the successful implementation and use of this model. Methods We used a two-stage process. First, five databases were consulted, with no date delimitation. We included systematic reviews of quantitative, qualitative, and mixed studies published in English, French, Spanish, or Portuguese. We followed guidance from PRISMA and the Cochrane Collaboration. Second, we used the Nursing Care Performance Framework to categorize the indicators, a comprehensive grid of barriers and facilitators to map the factors affecting HBH implementation, and a thematic synthesis of the qualitative and quantitative findings. Results Fifteen reviews were selected. We identified 26 indicators related to nursing care that are impacted by the use of HBH models and 13 factors related to their implementation. The most frequently documented indicators of HBH were cost of resources, problem and symptom management, comfort and quality of life, cognitive and psychosocial functional capacity, patient and caregiver satisfaction, hospital mortality, readmissions, and length of stay. Our review also highlighted new indicators, namely use of hospital beds, new emergency consultations, and use of healthcare services as indicators of resources of cost, and bowel complications, caregiver satisfaction, and survival time as indicators of change in the patient’s condition. The main facilitators for HBH implementation were related to internal organizational factors (multidisciplinary collaboration and skill mix of professionals) whereas barriers were linked to the characteristics of the HBH, specifically eligibility criteria (complexity and social situation of the patient). Conclusion To the best of our knowledge, this is the first review that synthesizes both the types of indicators associated with HBH and the factors that influence its implementation. Considering both the processes and outcomes of HBH will help to identify strategies that could facilitate the implementation and evaluation of this innovative model of care delivery. Systematic review registration PROSPERO CRD42018103380


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Conclusion: To the best of our knowledge, this is the first review that synthesizes both the types of indicators associated with HBH and the factors that influence its implementation. Considering both the processes and outcomes of HBH will help to identify strategies that could facilitate the implementation and evaluation of this innovative model of care delivery.

Systematic review registration: PROSPERO CRD42018103380
Keywords: Home-based hospitalization, Home hospital, Home care, Systematic review, Meta-analysis

Background
With the aging population and the growing prevalence of chronic diseases affecting all age groups, the integration of home care services is becoming a necessity for front line health service organizations around the world [1 -3]. Since hospitalization is one of the key factors in the increasing cost associated with the use of health services related to chronic diseases, it is essential to implement effective and safe alternatives to conventional hospitalization [4].
All over the world, emergency room overflows reflect on suboptimal performance of the healthcare system as it is currently organized and delivered [5][6][7]. In addition, hospitalization in emergency departments entails significant risks for older adults, including iatrogenic complications, functional and cognitive decline, and loss of independence [8,9].
Home-based hospitalization (HBH) offers an alternative model of care delivery subject to the same obligations as hospitals [10,11]. The terminology regarding this service model is inconsistent in the literature as many studies use hospital-based home, hospital at home, hospital in the home, and home-hospitalization. In some cases, these terms are used but do not involve substitution for in-hospital care. The operational definition for HBH that we adopt in this paper is a service that provides in-home hospital care to patients with complex clinical conditions who would be hospitalized in conventional facilities due to an acute episode [12] and require 24/7 monitoring and follow-up that is only available in the hospital [13]. The implementation of HBH would therefore optimize the use of resources by providing health services for specific groups who do not require conventional hospitalization.
In this regard, several countries, including the USA [14], Spain [15], Australia [16], Canada [17], and the UK [18], have implemented HBH, following the example of France which was one of the first jurisdictions to implement it [19,20]. The criteria for home admission are very heterogeneous, and the activity of HBH care varies greatly according to the main management methods: complex dressings, palliative care, and intensive nursing interventions [21].
A brief summary of Cochrane systematic reviews and meta-analyses comparing conventional hospitalization and HBH reveals that HBH would substantially optimize hospital bed [22] and would have a small advantage in readmissions [12,20,23] and patient satisfaction [22,24,25]. However, there was no significant difference between the two modalities of care in terms of cost (reduced length of stay in hospital) or improved health outcomes, including reduced mortality [20,[22][23][24]26].
The heterogeneity between systematic reviews reveals the varying degree of structuring of home care services with respect to the characteristics of the population and organization of services, the measures used, and the results reported [12,27]. Thus, it becomes a challenge to find the most advantageous model. Despite the growing interest in HBH models, their implementation is still difficult for countries that do not have national and federal standards governing this practice [9,13]. In general, arrangements for organizing HBH services, team composition, and organization of health professionals, as well as patient care and follow-up visits, are not well defined in the studies and precluding firm conclusions [12,27,28]. This limits the possibility to understand how organizational, clinical, economic, political, and social factors influence the implementation of this model of care.
The lack of knowledge about implementation factors compromises the identification of the expected effects in the delivery of HBH care and services. It also limits knowledge transfer about the organizational structure required to adopt this model of care between countries that have a comparable health system.

Why do this systematic review of reviews?
Several systematic reviews and meta-analyses have assessed a wide range of indicators related to HBH, including the cost of providing hospital-based home care compared to conventional hospitalization. However, these indicators are not organized into a structured framework and their measurement vary between studies, which makes difficult providing clear evidence of the effects of HBH on important outcomes. Moreover, no previous reviews have systematically synthesized evidence on the factors associated with the implementation of HBH models. Indeed, the implementation of a new model of care is synonymous with major changes and transformations in the organization of services as well as at the clinical, economic, political, and social levels [29,30].
This synthesis highlights the facilitating and limiting factors for HBH implementation together with its indicators, thus contributing to the knowledge base regarding this innovative model of care delivery for healthcare organizations.

Objectives
Systematically mapping the indicators of HBH as well as the factors associated with the success of the implementation and use of this model of care.
More specifically, this review covers the following questions: (1) What barriers and facilitating factors influenced the implementation of the HBH model? (2) What indicators (positive, negative, or neutral indicator) have been used to measure the HBH model?

Study design
As there are currently no guidance on reporting systematic reviews of reviews, we used the "Preferred Reporting Items for Systematic Review and Meta-Analysis" extension for network meta-analyses (PRISMA-NMA) guidelines [31] as a general framework to report this work. We also consulted methodological references on overviews of systematic reviews [32][33][34]. The PRISMA-NMA guidelines which contains 27-item checklist and a fourphase flow diagram.
This review was structured according to the formulation of the PICOS research question (Population, Intervention, Comparison, Outcomes, Study Designs) [32] which forms the basis for establishing the components and eligibility criteria for studies (Table 1). Our PROS-PERO protocol indicates the population of patients with chronic diseases, more specifically in palliative care because it was the target population of the larger project. However, we decided during the elaboration of the research strategy to expand the population including also patients in acute conditions in order to favor the inclusion of different models of HBH.
The methodological quality assessment grid for systematic reviews (AMSTAR 2) was used for assessing the quality of systematic reviews and meta-analyses included [35].
The nursing care performance framework (NCPF), developed by Dubois [36] (Appendix 1), has been adapted to map the indicators of HBH identified from systematic reviews. This model allows the systematic evaluation of the healthcare system in general, including nursing care, and its three subsystems (acquiring, maintaining, and deploying resources; transforming resources into services; producing changes in patient conditions). It proposes 14 dimensions and 51 indicators that allow performance evaluation of the whole nursing system using a multidimensional perspective that includes structure, process, and results and takes into account the influence of external factors.
The NCPF was chosen because in the HBH model, the coordination of care is centered on nursing practice [11,[37][38][39]. This model provides a group of indicators to evaluate nursing performance in the organizational model of HBH that could serve as a basis to orient evaluation of this model of care.
Regarding the factors that influenced the implementation of the HBH model, we adapted the concepts developed through research related to the classification of barriers and facilitators to implementing innovative technologies in healthcare [40][41][42][43]. This conceptual approach allows an explanation of the factors affecting the implementation and use of the HBH model in a complex and dynamic environment inherent to the healthcare system and defines the determinants of the adoption and diffusion of this innovation.

Protocol
The protocol for this review is registered in the international prospective register of systematic reviews (PROSPERO) under number CRD42018103380. We brought some changes to the protocol as we did not limit the population to HBH for palliative care, but rather included all populations that could benefit from HBH, since the included systematic reviews often considered several population groups or diseases. We also considered all relevant outcomes reported in the included systematic reviews.

Inclusion and exclusion criteria
Included publications were quantitative systematic reviews (including meta-analysis), qualitative reviews, and mixed studies reviews focusing on the factors associated with the implementation of HBH and its indicators of use, and published in English, French, Spanish, and Portuguese (languages spoken by the authors). As the

Selection of studies
The selection was made independently by two team members (CPMC, GICM). First, the titles and summaries of the systematic reviews were reviewed and selected according to the inclusion criteria. Then, the complete texts were evaluated. Publications that did not meet the inclusion criteria were excluded by documenting the reasons for exclusion. Any disagreement concerning study eligibility was resolved through discussion and consensus involving both examiners or involved a third author, if necessary. A flowchart was used to show the overall process of selecting studies [45].

Extraction of data
Data from the included reviews were extracted independently by two team members (CPMC, GICM), as recommended by the Cochrane Handbook [32], using a form based on the components of the PICOS question and primary and secondary outcome indicators. The following data were extracted: characteristics of the review (authors, year of publication, language, type of review, rationale, objectives), characteristics of the population (patient profile, health status, and care environment), characteristics of the intervention (type of service provided, context of care, duration of the HBH, intervention components, team composition, technologies used), comparisons between home and conventional hospitalization, primary and secondary outcomes (positive, negative, or neutral indicators of HBH and implementation determinants). For summarizing our qualitative findings, two team members (CPMC, GICM) adapted the grid with concepts developed through research related to the classification of barriers and facilitators to implementing innovative technologies in healthcare [40][41][42][43] as the analytical framework. CPMC and GICM independently performed data extraction and transposed extracted data into this framework using thematic analysis. We populated the data extraction grid in the Microsoft Excel software 2016. The quality of included reviews was independently assessed by the same two authors according to the AMSTAR 2 evaluation grid [35]. The strength of the evidence was assessed according to the GRADE approach [46].

Data synthesis
A narrative summary of the results of the included reviews was developed to describe the main indicators of HBH using the framework of Dubois [36]. Implementation factors were also synthesized narratively using the categories proposed by McGinn et al. [40] and Gagnon et al. [43]. The narrative approach is recommended to summarize and explain the results of systematic quantitative, qualitative, and mixed studies, especially the indicators of interventions and the implementation of interventions that have been shown to be effective [47,48]. Specifically on implementation factors, the reviewers identified sections of the publications that presented a relevant barrier or facilitator to implementation and use of HBH model and coded them according to the categories proposed in the grid. Then, we grouped the extracted data into four main categories of adoption factors, and each category was decomposed into specific factors.
To achieve this, quantitative data were categorized according to the frequency of each factor and its influence (facilitator or barriers as well as the frequency of each indicator (positive, negative, or neutral indicators) of using HBH at the level of patient, family, healthcare system, and society. Qualitative data were integrated into a thematic synthesis.

Search results
A total of 1069 records were identified from the search strategy. After removing duplicates and screening titles and abstracts, we examined 40 full texts, of which 15 reviews [12, 20, 22-26, 44, 49-55] were eligible for inclusion. All reviews showed indicators of HBH as well as the factors associated with the implementation and use of this model of care (by primary and secondary outcomes). However, the structure of included reviews did not allow us to present the outcomes by population groups. Appendixes 3 and 4 present the PRISMA extension checklist and the list of selected reviews with the frequency of primary studies, respectively. The overall process of review selection was summarized according to the PRISMA study flow diagram (Fig. 1), and details are provided regarding the primary reasons for exclusion and the full references of excluded publications (Appendix 5).

Characteristics of the reviews
The general characteristics of the included reviews, namely type of review, population, intervention, outcomes, and quality, are summarized in Table 2 and detailed in Appendix 6.
All reviews were published in English, except one that was published in Spanish, between 1998 and 2018, and more than half were published since 2012. The majority of reviews were from the UK (n = 9, 60%). The other six reviews were from Canada (n = 1), Australia (n = 1), Norway (n = 1), Spain (n = 1), Belgium (n = 1), and Denmark (n = 1).

Profile of admitted patients in HBH
Fourteen reviews included patient populations aged 18 years and older needing treatment during an acute episode of care, who would otherwise require hospitalization [12, 20, 22-26, 44, 49-55]. The other review focused on children and adolescents aged 0-18 years old [50].

Overview of the indicators of HBH
The results (see Fig. 2) are presented in association with the NCPF [36]: the function, the dimension, and the indicators, according to the frequency of data extracted from each systematic review (Table 3) and with the strength of evidence of according to the GRADE [46] approach identified in the systematic reviews that used it (Appendix 7).
Function 1: acquiring, deploying, and maintaining resources Economic sustainability Almost all reviews (14/15) outlined positive indicators related to cost effectiveness of resources [12, 20, 23-26, 49, 52-55], including the three new indicators identified in the HBH economic sustainability dimension of the NCPF, namely use of hospital beds [24], new emergency consultations [49,54], and use of healthcare services [24]. Only one review did not evaluate the cost [54]. The cost per episode of healthcare or per day basis associated   [12,20,23,24,52,53,55], and there could also be a saving of bed days a year, according to one review [26]. However, this benefit is offset when costs from a societal perspective were also considered, including formal and informal carer costs and production losses for the patient, over the acute and follow-up periods combined [20,23,24,52]. Some evidence indicates the possibility of substantial variation in the actual effect size [12,22,44,[49][50][51] by patient eligibility criteria [20,52], different countries, and various conditions [12].
Due to different methods to calculate costs and heterogeneity due to different currencies and different cost structures, identifying the cost-effectiveness of HBH model was not possible in some reviews [22,44,[49][50][51].

Function 2: transforming resources into services Nursing processes
Three reviews found a positive indicator of HBH on problem and symptom management [22,49,55] whereas one review found neutral indicator [12]. Among the documented outcomes, HBH reduced delirium [22] and provided improvements for depression [49,55] and nutritional status at 6 months follow-up [49].

Patient centrality in the nursing care delivery process
One review that documented continuity (reactivity) for patients and patient/family involvement (self-care/information/education) showed a positive indicator of HBH [23]. This review found that patient and carer education for recognition and management of acute exacerbation was associated with a lower rate of all-cause readmission.
In relation to informal caregivers, also considered users of this model of care, a review does not report any indicator of the HBH model on them, justifying the lack of data on the impact of home hospitalization on the family or informal caregivers [22]. This review indicates that the caregiver's willingness to take on the responsibilities associated with HBH is a determining factor that may restrict the degree to which HBH model can be implemented, and this may in turn impact on how these services reduce costs and reliance on secondary care in general [22].

Professional satisfaction
Professional satisfaction was reported in three reviews [22,25,51]. Indicators of professional satisfaction were mixed within and across the reviews: two reviews demonstrated positive indicators [22,51], and one demonstrated negative indicator [25]. Two reviews showed that the HBH staff perceived that providing care in the patient home facilitated participation in rehabilitation, that the service was better staffed than the usual discharge services provided, although the workload was similar to conventional hospitalization [22,51]. However, the evaluation of health professionals' perceptions about HBH, specifically that of general practitioners, presented limitations due to low response rate [25], although it Length of stay 6 1 2 Survival time* --1 *New HBH indicator identified in the systematic reviews and meta-analyses and integrated to the NCPF was higher when compared to the response rate of conventional hospital staff [25].

Function 3: producing changes in patients' condition Risk outcomes and safety
Three reviews found negative indicators [25,50,53], two reviews found neutral indicators [53,55], and one found positive indicators [25] on risk outcomes and safety. The negative indicators included intravenous infections due to perfusion difficulties for which hospitalization was needed, device-related infection [53], and episodes of subcutaneous inflammation along intravenous lines [50]. Pressure ulcers/skin integrity was mentioned in the risk of advancing cellulitis in participants with cellulitis, and pulmonary infections were related to the increased antibiotic therapy for participants with COPD allocated to HBH [25]. Also, the need for management of drug administration was cited before the occurrence of occlusion of central venous catheters [50]. Nonetheless, two reviews mentioned that they found neutral indicators on medication management and that the adverse events described (number of reported toxicities, perfusion difficulties, missed doses, and adverse drug reactions) were comparable between HBH and usual care [53,55].
The only review that found positive indicators cited the reduction in the number of urinary and bowel complications in patients allocated to HBH [25], the latter being a new indicator identified in the risk outcomes and safety dimension of the NCPF.

Patient comfort and quality of life related to care
Positive indicators on symptom management were reported in three reviews [25,49,50]. The control of symptoms in adult patients (pain, nausea/vomiting, constipation, diarrhea, breathlessness, anxiety, and depression) improved, but assessments varied by assessor [25]. Fewer patients with stroke allocated to HBH reported anxiety [49]. The successful control of nausea and vomiting in children was also highlighted [50].
Positive indicators on the quality of life (QoL) of patients in HBH were reported in five reviews [25,[49][50][51]55], and other three reviews found no association between HBH and health-related quality of life indicators [12,23,53]. The improvement in QoL among HBH patients may be facilitated by treatment in a familiar environment, with greater independence and less technically oriented care [49]. Furthermore, HBH presented a significantly reduced risk to patients for being in residential care at follow-up [51]. An improvement was reported in QoL at both 6 months [25,55] and 12 months, for patients with heart failure [55]. QoL in children and parents was overall improved when the child received intravenous chemotherapy at home with HBH [50].
HBH patients experienced improvements in cognitive and psychosocial functional capacity with regard to depression [49,52,55], especially in patients with stroke or acute chronic heart failure [25], and better psychological well-being for patient with stroke [51]. Fewer participants with a mix of conditions receiving HBH care experienced short-term confusion during an episode of care, and fewer participants with dementia were prescribed antipsychotic drugs [25] or had problems with sleep, agitation, aggression, and feeding [52].
Improvements in activities of daily living were also reported for patients with stroke, COPD, or heart failure at 6-month follow-up [25]. Nutritional status improved for adult patients with acute decompensation of chronic heart failure [49], and fewer patients with dementia assigned to HBH had problems with feeding [52].
The assessment of physical functional capacity for depression and anxiety did not differ between HBH and usual care due to insufficient evidence between groups for most measures [25,51,52]. The lack of indicator on functional capacity was also reported in two other reviews [22,24]. The most recent review emphasized that HBH for end-oflife care may make little difference in functional status, psychological well-being, or cognitive status [24].
A negative indicator on physical functional capacity was reported in patients with stroke mentioning that these patients worsened with HBH intervention compared with treatment in a stroke unit [55].
A considerable proportion of cancer patients, including children and their parents, preferred HBH [50,53]. Most-valued aspects of HBH are the quality of communication, personal care received [25], frequent and timely visits, and close attention to details [51].
The negative indicator reported concerned women recovering from a hysterectomy and allocated to HBH who had to resume parental responsibilities before being well enough [51].
The satisfaction of informal caregivers was a new indicator documented in the dimension patient and caregiver satisfaction of the NCPF. Four reviews demonstrated positive indicators [20,25,50,52], three showed neutral indicators [22,25,51], and two showed negative indicators [25,44].
HBH increased caregiver satisfaction compared to conventional hospital care [20,25,44,50,52], notably by lowering relatives' stress [25], but did not affect carer burden [20] and anxiety of parents of children in HBH [50]. The caregivers reported that although hospital would potentially relieve them from caring, the upheaval of visiting hospital and the accompanying anxiety was a less satisfactory option [25].
However, the results on satisfaction are still uncertain, according to the weak evidence found in three reviews [22,25,51], especially for caregivers of patients in endof-life care. Caregivers expressed lower levels of satisfaction with HBH, compared with hospital care, and experienced lower morale if the participant survived more than 30 days. There was also little or no difference for caregiver bereavement response 6 months following patient's death [25,44].

Joint contribution of nursing with other care
Seven reviews reported neutral indicators of HBH on mortality at 3-to 6-month follow-up [22, 24-26, 49, 51, 55]. However, positive indicators were described in five reviews that found a tendency to decrease mortality within 2 to 6 months favoring HBH in the middle age group [12,20,23,52], and a reduction in mortality for patients with heart failure compared to conventional hospitalization [54].
HBH indicators on hospital readmission were neutral in seven reviews, as no strong evidence was found on the rate of readmission [22,25,26,49,51,52,55]. However, four reviews mentioned positive indicators with evidence of moderate quality related to the reduction of readmission for HBH patients compared to conventional hospitalization [12,20,23,54], notably in patients with heart failure and COPD [54].
The difference in length of hospital stay varied among reviews, showing a reduction between 4 to 14 days [20,24,55]. The positive indicators of HBH on length of stay were documented in six reviews [22-24, 51, 52, 54], two reviews found neutral indicators due to the heterogeneity of the data [25,55], and a negative indicator was reported in one review [49].
HBH reduced the length of stay for patients with a mix of conditions [22-24, 51, 52, 54]: COPD [54], stroke [22][23][24]52], early discharge of patients following elective surgery [51]. However, the total period of care tends to be longer according to one review [23]. Another review showed a significantly longer length of stay in the HBH intervention, but this indicator might be due to the heterogeneity of the data [49].
With respect to survival, a new indicator identified in the dimension joint contribution of nursing with other care, one review found neutral indicator on survival time for HBH end-of-life care [25].

Overview of the facilitators and barriers to the implementation of HBH model
In total, 41 distinct facilitators and barriers to implementing HBH model were identified and classified in the different categories of factors from the extraction grid. Among these elements, 35 (85%) were classified as facilitators for implementation of HBH and six (15%) as barriers. The complete list of factors can be found in Table 4.

Factors related to HBH characteristics
The included reviews were conducted in different countries with different healthcare systems. Nonetheless, there were some important common features about definition of HBH, which included replacement of both acute and subacute hospitalization [20,22] in complex patients with a high degree of comorbidity [53,54] and different intensities of home-based care [20,49]; care being coordinated in each of the schemes by a multidisciplinary team, home visits, provision of 24-h cover if required, with access to a doctor [12, 20, 23-25, 49, 52, 53] and monitoring, diagnostic testing, home nursing care for the administration of IV medications [49,53], and a safe home environment [12,20,23,25,49,52].
Regarding the factors related to the characteristics of HBH, a total of eight elements pertain to this category, with two of them identified as barriers and six as facilitators. The most recurrent adoption factor was HBH characteristics, with five extracted elements. It was seen as a facilitator in three reviews [20,23,55] and as a barrier in two reviews [23,25]. The configuration of this innovation was characterized mainly by the condition of the individual's home and the social support networks existing in the HBH model [55] during the day and night [23]. Length of HBH stay was also considered a barrier in HBH model with limited duration [20]. In this context, nursing care available only in the last 2 weeks of life [25] and the heterogeneity of the level of clinical and social support provided in HBH [23] were two shortcomings in the HBH models.
Patient empowerment was mentioned as a facilitator in three reviews [23,25,49]. The educational component on self-management provided at home instrumented participants and their families to identify care goals and expected course of disease and outcomes, as well as the probability of success of various treatments [23,25,49].
Individual factors: knowledge, attitude, and sociodemographic characteristics Individual factors represented three of the elements identified in the review, two as facilitators and one as a barrier. Only factors related to patients were underlined: confidence in HBH developer or provider, autonomy (health empowerment), and socio-demographical characteristics. The patient's preferred place of care was the home, which facilitated the implementation of the HBH model [51], with strong evidence on the applicability and safety of the HBH model to the predominant characteristics of patients, aged 75 years or older [23]. Only one individual factor was identified as a barrier in HBH, namely lack of confidence in HBH developer, because a small proportion of patients refused HBH and were admitted to conventional hospital [52]. Evening and night cover was provided by a direct line to medical chest unit or provided by district nurses [26].
Nurses reported that additional help should have been provided for caregivers looking after the participants and for night nursing [24].

External factors: human environment
External factors related to the human environment refer to the clinical team and their interactions with patients. The only factor identified in this category as a barrier for HBH in children was the miscommunication in teaching parents that affected the patient and health professional interaction [50].

External factors: internal organizational environment
Most of the elements reported in the reviews belong to this category, with 27 considered as facilitators and 2 as barriers.
Characteristics of the structure of work related to practice size [25] and nature of work, specifically the work flexibility for evening and night cover of nursing team [26], were identified as facilitators for HBH. Likewise, provision of material resources (for example, telephone support [23,25,49], oxygen therapy, nebulised bronchodilators, intravenous antibiotics and steroids [23], laboratory tests, and electrocardiogram done at home [49]) was also seen as potential facilitators for HBH model implementation.
Two perceived barriers were workforce issues related to reduce nursing staff, especially the night staff, and lack of human resources for 24-h care. The heterogeneous profile of the included patients also required training for nurses, especially for daily home visits. Team composition of the HBH models was heterogeneous and there was a lack of data on who was responsible for each care delivery [24].

Summary of main results
This systematic review of reviews provides a mapping of the indicators (positive, negative, or neutral indicators) of the HBH model, categorized by the dimensions of nursing care, as well as the factors identified as barriers or facilitators to its implementation.
With respect to the indicators of HBH model, our review corroborates the positive clinical and economic indicators previously documented since 1998. The main contribution of this review is to map these indicators according to the NCPF, which provides a structured approach to analyze how the HBH model works to produce the identified outcomes.
Moreover, our work provides a first review of the factors that could facilitate or hinder the implementation of the HBH model. Our results show that 13 implementation factors influenced the implementation of the HBH model. Among them, the multidisciplinary collaboration and skill mix of professionals inherent to the internal organizational factors were identified as the main facilitators. Conversely, some characteristics of the HBH model, specifically related to the clinical criteria of eligibility and social situation of patients were identified as barriers to implementation.
Based on the AMSTAR2, the overall quality of the included reviews was good, with a number of high and moderate quality reviews, and only two reviews with important methodological limitations. The lack of systematization of data in these reviews led to a lower quality score on the AMSTAR2 scale because we lacked information for assessing the risk of bias. This result may be related to clinical trials that still lack detailed information on the methods used and present methodological flaws that compromise their internal validity [56,57].

Discussion of results with respect to the NCPF
In relation to the first function of the NCPF (acquiring, deploying, and maintaining nursing resources), almost all reviews outlined outcomes linked to a dimension of the NCPF called economic sustainability [36]. The positive indicator related to the potential of HBH model to reduce healthcare spending does not directly reflect the total cost of the resources used, including the direct costs for the health sector and the indirect costs related to the impact on families and society, which makes it difficult to assess the cost-effectiveness [12,20,22,23,26,44,[49][50][51][52]55]. Two reviews mentioned the importance of service continuity offered in the HBH model since the variations in the way the service is delivered may also account for differences in cost, specifically in HBH schemes that did not provide 24-h care [22,51]. Regarding the cost of readmission, Echevarria et al. [23] identified conceptual confusion highlighting the need for further detail on this event for patients returning to the hospital during HBH and whether those patients are readmitted at home during the follow-up period.
With respect to the second NCPF function, nursing processes and professional satisfaction were highlighted in the transformation of nursing resources into nursing services. This function captures the benefits of nurse coordinating care in the HBH model for better patient management, particularly with respect to education including selfmanagement [22,49,55]. Another review confirmed the importance of patient/family involvement in self-care [23].
Although the HBH model is considered satisfactory for patients in the view of the professionals involved in hospital care, the perceptions of health care providers need to be explored, especially the professional satisfaction related to the work environment characteristics (perceived autonomy, role tension, collaboration). One review highlights that professional satisfaction may determine the potential for adoption of the HBH model and its effective implementation as an alternative hospital model inserted in the existing primary care services [25].
In the third function of the NCPF, the indicators concern the joint contribution of nursing and other systems aimed at the production of changes in patients' conditions. The environment was associated with positive indicators on patient quality of life [49,50] and satisfaction of patients and their families [25,[50][51][52][53]. In these studies, the HBH environment was qualified as a family environment adapted to the individual that improved the trust relationship with health professionals, increased autonomy, and improved access to the service [49,50]. For patients and caregivers, home was considered as the preferred place for treatment and hospitalization. Although patients and family members are satisfied with the HBH model, it is still necessary to investigate in detail the participation and perception of family members associated with home hospitalization, particularly regarding the responsibility and the social aspects involved.

Discussion of results with respect to the factors associated to implementation of the HBH model
Given the considerable attention that the HBH model receives globally, it seemed important to identify the factors identified as facilitators or barriers to its implementation by healthcare organizations. The main findings of this review point out that several internal factors of the organizational environment and factors related to the characteristics of the HBH model influence the implementation of HBH.
Factors related to the characteristics of the HBH model that influence its implementation include innovation characteristics [20,23,24,55] and patient empowerment [23,25,49]. Some important features of the HBH model are coordinated care in each multidisciplinary team, 24-h provision with access to a physician, and a safe home environment.
In fact, the diversity of HBH schemes organized according to the national legislation and health systems of the countries was a barrier considered in two reviews [23,25] because of the different structures of home hospitalization, including the variation of the size of healthcare teams, follow-up visits, and the provision of social and technological support.
The role of HBH model to support patient empowerment has been mentioned in three reviews [23,25,49]. In HBH model, healthcare professionals invested in managing patients and education of patients and families for self-care, supporting the idea of a user-centered approach promoted by the level of care provided and intensity of contact with healthcare professionals.
In addition, the support of technology for management and communication among the professionals of the multidisciplinary team [23,25,49] and clinical support of HBH patients [23,49] were also identified in some reviews, albeit less frequently. Although technological resources were a facilitator in the implementation of the HBH model, only a few studies highlighted the need for accessibility to mobile technologies such as telephones and diagnostic equipment.

Agreements and disagreements with other systematic reviews
Our systematic review of reviews focused on bringing together the scientific evidence on the HBH model published over the last two decades.
We have identified a systematic review of systematic reviews by Conley et al. [58] through our research strategy. Unlike our systematic review, Conley et al. [58] did not focus solely on HBH but examined systematic reviews of alternative management strategies to hospital inpatient unit, including outpatient management, rapid diagnosis units, observation unit, and HBH. Of the 25 systematic reviews selected by Conley et al. [58], only six reviews were related to HBH and of these, four systematic reviews [12,20,49,51] were included in our review. The two others were excluded because they were not systematic reviews.
In relation to clinical outcomes, Conley et al.'s review [58] found positive indicators on cost of resources and patient and caregiver satisfaction for multiple conditions, and neutral indicators on hospital readmission and mortality in HBH management compared with conventional inpatient admission across many acute medical conditions (including heart failure and COPD exacerbations, cellulitis, community-acquired pneumonia, pulmonary embolism, and stroke). They also showed a critical need to determine optimal patient eligibility, and date riskstratifying algorithms require further evaluation and validation. Diverging from our results, Conley et al. [58] did not find any positive indicators related to additional patient outcomes (functional ability, quality of life, or disease-specific outcomes) in HBH.

Study strengths and limitations
This systematic review of reviews has many strengths. Firstly, a comprehensive search strategy was developed and implemented in partnership with a health information specialist. Secondly, findings that emerge from the analysis of reviews focus on the evaluation of the indicators of HBH models and the factors influencing their implementation in the form of a narrative synthesis, rather than from the analysis of individual studies. Third, the data extraction process was done with the use of the NCPF and a comprehensive grid of barriers and facilitators to implementation, which supported the organization and the analysis of findings. Moreover, most of the reviews included in this review had a good quality according to the AMSTAR2. However, AMST AR2 is not intended for the assessment of mixed methods systematic reviews that include qualitative studies, this being one of the limitations of our study.
Some limitations have also been identified. We were limited by the information provided by the reviews authors, which also highlighted a great heterogeneity of HBH schemes in terms of definition, population, interventions, and variety of outcomes. It must be emphasized that some indicators may be overestimated in this review because they come from the same primary studies that have been compiled in different systematic reviews. Despite these limitations, our synthesis contributes to the knowledge base on the HBH model, the facilitating and limiting factors of its implementation, together with the indicators of this model of care in the organization of services, as well as at the clinical, economic, political, and social levels.

Conclusions
Many systematic reviews have been published on homebased hospitalization, indicating the growing interest in evaluating this intermediary resource on the health services network, specifically the impact on patients, their families, and society.
Our findings provide a mapping of the indicators of the HBH model, categorized by the dimensions of nursing care, as well as the factors identified as barriers or facilitators to its implementation.
The indicators according to the NCPF identified in studies on the implementation of this care model totaled 26 indicators related to nursing care in relation to the cost of resources, management of problems and symptoms, comfort and quality of life, cognitive and psychosocial functional capacity, patient and caregiver satisfaction, hospital mortality, readmissions, and length of stay. Among these, six new indicators were discovered in the analysis of the indicators of the HBH model, namely use of hospital beds, new emergency consultations, and use of healthcare services as indicators of resources of cost, and bowel complications, caregiver satisfaction, and survival time as indicators of change in the patient's condition. These new indicators provide additional information in the evaluation of the total cost of resources used in the HBH model, including direct costs and indirect costs, and in the evaluation of the production of changes in patients' conditions based on the joint contribution of nursing and other linked systems in this care model. However, it is still necessary to investigate in detail the cost-effectiveness of the HBH model and the participation and perception of patients and family members associated with home hospitalization.
Regarding the factors that influenced the implementation of the HBH model by health organizations, our review identified 13 factors related mainly to internal organizational factors (multidisciplinary collaboration and skill mix of professionals). Two of these facilitators were seen as important for the implementation of the HBH model in the included reviews, specifically the combination of competence of health professionals and the coordinated care in each multidisciplinary team in home hospitalization. The main barriers were linked to characteristics of the HBH, specifically eligibility criteria (complexity and social situation of the patient) because of the different structures of home hospitalization organized according to the national legislation and health systems of the countries. Since the multidisciplinary collaboration and the skill mix of professionals were found as internal organizational facilitating factors, the limited and transitory approach to the use of technologies in the implementation of the HBH model presented in the systematic reviews analyzed call for further investigation.
We suggest that the use of technologies in the implementation of the HBH model must be addressed in detail with respect to continuity of care and interprofessional collaborations centered on patients and their families, according to the nature of the experience, interests and needs to define the information, and communication technologies interventions necessary for the HBH model.
Although only three reviews included qualitative studies [53][54][55], we have identified evidence that valued the description of the process of organizing this alternative delivery model to hospital care, highlighting the facilitators and barriers associated with the successful implementation and use of this model of care. Our review shows that the documented indicators are directly related to changes in patient condition and were identified in intermediary resources such as HBH inserted in the care and service trajectory with an impact on structure, process, and results, taking into account the influence of external and internal factors. However, evidence is lacking regarding many outcomes, notably safety and burden on family/informal caregivers.    Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale. Clearly describe eligible treatments included in the treatment network and note whether any have been clustered or merged into the same node (with justification).

6, 7
Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.
7 Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.

54
Study selection 9 State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).

7
Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.

8
Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.

6
Geometry of the network S1 Describe methods used to explore the geometry of the treatment network under study and potential biases related to it. This should include how the evidence base has been graphically summarized for presentation, and what characteristics were compiled and used to describe the evidence base to readers.  Provide a network graph of the included studies to enable visualization of the geometry of the treatment network.
Presentation of network structure S3 Provide a network graph of the included studies to enable visualization of the geometry of the treatment network.

67
Summary of network geometry S4 Provide a brief overview of characteristics of the treatment network. This may include commentary on the abundance of trials and randomized patients for the different interventions and pairwise comparisons in the network, gaps of evidence in the treatment network, and potential biases reflected by the network structure.

11, 76
Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.

11, 76
Risk of bias within studies 19 Present data on risk of bias of each study and, if available, any outcome level assessment.

This is not applicable
Results of individual studies 20 For all outcomes considered (benefits or harms), present, for each study: (1) simple summary data for each intervention group, and (2) effect estimates and confidence intervals. Modified approaches may be needed to deal with information from larger networks.

9-11, 76
Synthesis of results 21 Present results of each meta-analysis done, including confidence/credible intervals. In larger networks, authors may focus on comparisons versus a particular comparator (e.g., placebo or standard care), with full findings presented in an appendix. League tables and forest plots may be considered to summarize pairwise comparisons. If additional summary measures were explored (such as treatment rankings), these should also be presented.

15-35
Exploration for inconsistency S5 Describe results from investigations of inconsistency. This may include such information as measures of model fit to compare consistency and inconsistency models, P values from statistical tests, or summary of inconsistency estimates from different parts of the treatment network.

39-41
Risk of bias across studies 22 Present results of any assessment of risk of bias across studies for the evidence base being studied.

This is not applicable
Results of additional analyses 23 Give results of additional analyses, if done (e.g., sensitivity or subgroup analyses, meta-regression analyses, alternative network geometries studied, and alternative choice of prior distributions for Bayesian analyses).

Summary of evidence
24 Summarize the main findings, including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., health care providers, researchers, and policymakers).

36-39
Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias), and at review level (e.g., incomplete retrieval of identified research, reporting bias). Comment on the validity of the assumptions, such as transitivity and consistency. Comment on any concerns regarding network geometry (e.g., avoidance of certain comparisons).

40-41
Conclusions 26 Provide a general interpretation of the results in the context of other evidence and implications for future research.

41-42
Funding Funding 27 Describe sources of funding for the systematic review and other support (e.g., supply of data); role of funders for the systematic review. This should also include information regarding whether funding has been received from manufacturers of treatments in the network and/or whether some of the authors are content experts with professional conflicts of interest that could affect use of treatments in the network.