Public-private partnerships in primary health care: a scoping review

Background The Astana Declaration on Primary Health Care reiterated that PHC is a cornerstone of a sustainable health system for universal health coverage (UHC) and health-related Sustainable Development Goals. It called for governments to give high priority to PHC in partnership with their public and private sector organisations and other stakeholders. Each country has a unique path towards UHC, and different models for public-private partnerships (PPPs) are possible. The goal of this paper is to examine evidence on the use of PPPs in the provision of PHC services, reported challenges and recommendations. Methods We systematically reviewed peer-reviewed studies in six databases (ScienceDirect, Ovid Medline, PubMed, Web of Science, Embase, and Scopus) and supplemented it by the search of grey literature. PRISMA reporting guidelines were followed. Results Sixty-one studies were included in the final review. Results showed that most PPPs projects were conducted to increase access and to facilitate the provision of prevention and treatment services (i.e., tuberculosis, education and health promotion, malaria, and HIV/AIDS services) for certain target groups. Most projects reported challenges of providing PHC via PPPs in the starting and implementation phases. The reported challenges and recommendations on how to overcome them related to education, management, human resources, financial resources, information, and technology systems aspects. Conclusion Despite various challenges, PPPs in PHC can facilitate access to health care services, especially in remote areas. Governments should consider long-term plans and sustainable policies to start PPPs in PHC and should not ignore local needs and context.


Background
Achieving the highest possible level of health is a fundamental right for every human being [1]. Two years ago, 40 years after signing the Declaration of Alma-Ata (1978) [2], world leaders reinstated that 'strengthening Primary Health Care (PHC) is the most inclusive, effective and efficient approach to enhance people's physical and mental health, as well as social well-being' [3]. The Astana Declaration on PHC (2018) reiterated that PHC is a cornerstone of a sustainable health system for universal health coverage (UHC) and health-related Sustainable Development Goals. It also called for all stakeholders to work as partners while taking joint action to build stronger and sustainable PHC [3]. When implementing this Declaration, countries will choose their unique paths towards UHC. Regardless of their choice, all of them would require effective cooperation and involvement of all major stakeholders (i.e., patients, health professionals, the private sector, civil society, local and international partners, and others).
Previous studies have shown that, despite substantial contributions and previous successes, provision of PHC services solely via the public sector providers has its limitation and some potential problems are welldocumented (e.g., shortage of human resources, inefficient institutional frameworks, inadequate quality and efficiency due to a lack of competition, particularly in remote and rural areas) [4,5]. In response to these challenges, some suggested that public-private partnerships (PPPs) initiatives could help to make PHC services provision more effective and efficient [6][7][8][9][10][11][12]. PPPs are voluntary cooperative arrangements between two and more public and private sectors in which all participants agree to work together to achieve a common purpose or undertake a specific task and to share risks and responsibilities, resources and benefits [13]. The flexible nature of PPPs provides a framework for developing and adapting existing structures to meet the specific needs of each project [14]. For instance, among the objectives of PPPs could be the establishment of a sustainable financial system; capacity-building reforms and management reforms in the public and private sectors; preventing unintended outcomes in the growth of the private sector in health; cost control and improving the health of the community; facilitating socio-economic development; improving PHC services coverage, quality, and infrastructure; as well as increasing the demand for health services [15].
Local support and private initiatives could become viable when improving PHC performance under a PPP, particularly in a situation when PHC does not have the necessary facilities to provide services, the utilisation of PHC services provided by the public sector is low, and there is a lack of effective mechanisms to evaluate and monitor its performance [5]. Private providers may also play an important role in the management of public health problems, such as malaria, sexually transmitted diseases, and tuberculosis (TB) [4,16]. It was previously shown that among the main reasons for service uptake from private PHC providers were better geographic access, shorter waiting times, more flexible opening hours, easier access to staff consultations and medication, and more confidentiality regarding disease-related symptoms [4,[17][18][19][20]. Moreover, the use of PPPs can significantly reassure and reduce the fear of privatising health care services [6]. Not surprisingly, PPPs are rapidly expanding and becoming an integral part of effective health interventions [21]. They have been tested as a means of ensuring the provision of comprehensive PHC service is efficient, effective, and fair [22]. PPPs are also often perceived as an innovative method that can produce desired results, particularly when the market fails to distribute health benefits to those who need them (i.e., disadvantaged and the poor people in developing countries) [23,24].
Our scoping review aimed to examine evidence on the use of PPPs in the provision of PHC services and answer the following questions: What target groups have been assigned to receive PHC services via PPPs? What kind of PHC services and processes were provided via PPPs? What arrangements or methods have been used to transfer PHC services to a private sector? What are the results of the service delivery using PPPs? What is the experience of PHC service users? What were the lessons learnt?

Data sources and search strategy
Six databases (ScienceDirect, Ovid Medline, PubMed, Web of Science, Embase, and Scopus) were searched between September and October 2018 for studies reporting on PPPs models used in PHC services provision. We used the following search terms: PPP or public-private partnership(s), public-private participation, public-private collaboration, public-private engagement, public-private mix, in combination with PHC or primary health care, primary healthcare, health care, healthcare, public health. A detailed search strategy for each database can be found in Appendix. The publication language was restricted to English. There were no time restrictions. We supplemented our review by a grey literature search conducted using the World Health Organization databases and websites of private health institutions. Additionally, the references of all included papers were searched for articles not identified through electronic searches.

Study selection
The titles and abstracts of documents were assessed against the inclusion and exclusion criteria (Appendix)      by two co-authors (NJ and LD). Any disagreements were be resolved by a third independent reviewer (JST). References were managed using EndNote X8 (Thomson Reuters, Philadelphia, PA, USA).

Data extraction and synthesis
We extracted the following information from the studies included in the review: setting, objectives, type of study, services, type of model, results, challenge, and recommendation (Table 1). Based on extracted data, we identified themes related to challenges, design, and implementation recommendations of PPPs projects in PHC service provision.

Results
The results of the screening process are shown in Fig. 1.
In total, 3488 documents were screened by title and abstract for possible inclusion in the review. Additional 14 documents were identified through the manual search. After screening all titles and abstracts, the full text of 120 documents was assessed against the eligibility and exclusion criteria, and 61studies were selected and included in the final review (Table 1). Of 61 selected studies, 32 studies were conducted in Asian countries; 11 studies in African countries; 11 studies in North and South American countries; one study was conducted in several different countries; three studies in the UK; two studies in Switzerland and one study in Australia. Of 61 selected studies, ten (16.3%) were descriptive, nine (14.7%) were qualitative, eight (13.1%) were case studies, eight (13.1%) were intervention studies, eight (13.1%) were reviews, seven (11.5%) were cross-sectional comparative studies, five (8.2%) were cross-sectional studies, three (4.2%) were cohort studies, and three (4.2%) were prospective studies. We observed that reported PPPs fell into one of the three broad categories: PPPs contracted out for basic PHC services, PPPs in health education and promotion programs, and PPPs in services for infectious diseases. Hence, we used this categorisation to summarise our findings.

PPPs contracted out for basic PHC services
A wide range of basic PHC services in Iran, England, Pakistan, India, Nigeria, Cambodia, Brazil, Arizona (US) and Bangladesh (i.e., prevention, promotion, and medical care, including maternal and child health care, family planning, environmental health, school health, health education, immunisation services, health promotion, common diseases treatment, malaria management, maternity services, postpartum services, and vaccination against influenza) was outsourced to PPPs and delivered to specific target groups (i.e., children, mothers, pregnant women, industrial workers, poor residents in the remote areas). The provision of these basic PHC services (infrastructure, procurement, and services management) was contracted out to private sector providers to facilitate better access and coverage of the population. The majority of studies reported that the provision of basic PHC services by private sector actors increased access to services, improved aspects of care, and resulted in various positive outcomes [5, 7, 10, 12, 23, 33, 39, 44-46, 49, 53, 60, 64, 65]. However, there was also some criticism as well. For example, Baig et al. [6] showed that the management of immunisation services, health promotion, disease treatment, and malaria by PPPs could also be seriously inadequate. Mahan et al. [35] also reported that due to being perceived as having poor quality by the local population, the uptake of institutional and maternal delivery provided in the private hospitals was low despite being offered free of charge.

PPPs in health education and promotion programs
Studies provided evidence regarding successful PPPs project implementation in the field of health education and promotion (i.e., oral health, sexual health, screening programs, and nutrition). For example, a PPP launched in 2010 by the FDI World Dental Federation and the Unilever measurably improved the oral health among children by encouraging children in kindergartens and schools, student mothers and the general population to brush teeth with a fluoride-containing toothpaste at least twice a day [11,28]. The comprehensive Oral Health Program created by the New York Dental College [38] for preschool children from low-income families and the Central Massachusetts Oral Health Initiative (CMOHI) [62] in the US for mothers, pregnant women, and children, also increased access to oral health care.
In the field of sexual health in South Africa, the North Star Alliance (a not-for-profit, non-governmental organisation established in 2006) united the transport sector in its response to the AIDS pandemic. It provided healthcare service package in roadside wellness clinics for truck drivers, sex workers, and their clients, as well as individuals from surrounding communities that do not have access to clinics otherwise. They also referred patients with complications to other health facilities in collaboration with the government and other nongovernmental organisations [31]. In Australia, a partnership between the research institutions and the telecommunications service provider was established to promote sexual health. The research institutes created the content of the sexual health campaign sent via text messages, while the telecommunications service provider performed randomisation of eligible mobile advertising subscribers for broadcasting the text messages [35].
In the field of breast and cervical cancer screening, in the US, the cooperation of a public institution with a group of private physicians, community clinics and hospitals led to a provision of better quality screening services. These included the provision of updated diagnostic services, the dissemination of educational, cultural and general information to low-income groups, racial and ethnic minorities, and senior women [36]. In South Africa, a package of interventions to prevent cardiovascular diseases among poor citizens was designed and implemented with the participation of the private sector, which had an overall positive reaction of the population [69]. In the field of mental health screening, a successful project was launched in Iowa (the US) through the Commonwealth Fund's Assuring Better Child Health and Development II project. This project created a coalition of public and private partners that focused on designing, testing, and identifying best practices for enhancing health care providers' mental health screening and referrals for all young children and their families, and ensuring effective coordination of assessment, intervention, follow-up, and communication back to the primary care practitioners [63].
In the field of nutrition, in 2010, in the US, the National Fruit & Vegetable Alliance, United Fresh Produce Association Foundation, the Food Family Farming Foundation, and the Whole Foods Market together launched the School Salad Bars initiative. This program provided resources and support to schools implementing the School Salad Bars initiative to raise awareness of the use of school salad bars, promote the consumption of fruits and vegetables among school students and improve their nutrition. This initiative resulted in an uptake of this program by approximately 700,000 students in 2012 [37]. Another successful global project was implemented in Asia (China and India), Africa (South Africa), Europe (Germany, United Kingdom), and Latin America (Brazil and Mexico). It fostered developing healthy diet habits and promoted the adoption of a physically active lifestyle among children, adolescents, women, mothers, and pregnant women [54].
In the field of health research, a successful PPP in Texas (the US) was established to prevent childhood obesity by focusing research on improvements in children, family, and community health through etiologic, epidemiologic, methodologic, and intervention research [55]. Other successful partnerships (e.g., Medicines for Malaria Venture and Global Alliance for TB Drug Development) have been implemented to facilitate universal access to essential drugs and health services, accelerate research and development in the fields of vaccines, diagnostics, and drugs for neglected diseases [52].

PPPs in services for infectious diseases
Studies also provided evidence regarding successful PPPs in the delivery of infectious disease services (i.e., malaria, TB, HIV/AIDS). PPPs in malaria case management in Tanzania and Ethiopia led to successful results and increased benefits among pregnant mothers, infants, and patients with malaria [25,42]. PPPs formed by governments, international donors, and pharmaceutical companies in India and several African countries were also successfully used to control AIDS and provide diagnostic and treatment services to suspects and AIDS patients [57,61]. PPPs were also used for the provision of diagnostic, treatment, and management of TB in Zambia, Vietnam, Indonesia, South India, Nigeria, Kenya, Nepal, Uganda, Korea, Bangladesh, and South Africa [4,8,13,20,22,26,29,34,40,41,43,47,50,51,56,58,59,61,66]. The following models of partnerships were reported: PPPs, Public-Private Mix (PPM), Public-Private Workplace Partnership (PWP), and Public-NGO Partnership (PNP). PWP and PNP models were used successfully to provide TB services in South Africa. Sites using PWP were reported to have the highest score of all aspects of quality of care (structure, process, and outcomes). PWP and PNP models were similar to solely public providers in terms of process quality, reflecting a very good knowledge of the treatment guidelines among both private and public providers [4]. PPM was used as a strategic initiative to engage all private and public health care providers in the fight against TB, using international health care standards [47,71]. Unlike PPP, which is based on long-term contracts with risk sharing and decision-making and a high level of collaboration, PPM involves actors from all sectors for non-contractual collaboration with a vertical disease focus [72]. Overall, evidence suggests that the use of various models of partnerships led to an increase in the TB case detection rates and the success of curative services [4,8,13,20,22,26,29,34,40,41,43,47,50,56,58,59,61,66]. Among the mechanisms and tools used to achieve this success were the design of referral forms and treatment cards, the implementation of the referral mechanism, the free distribution of medication, and the encouragement of patients to complete the course of treatment. Only two studies reported that participation of the private sector in TB control and care resulted in below the optimal level [29] and poor treatment outcomes [47].

Challenges and recommendations
Despite some positive outcomes and achievements, detailed analysis of studies results showed that partnerships between public and private sectors faced multiple challenges, particularly during the starting and implementation phases. We grouped these challenges into five areas: education, management, human resources, financial resources, and information and technology systems ( Table 2).
In education, among main problems were an inadequate level of knowledge related to testing and treatment procedures and inadequate knowledge for justification of people to participate in collaborative projects by providers [38,51,56,61,67]. In management, challenges encompassed lack of strategic vision and commitment from various partners, poorly defined roles and expectations, difficulties in member coordination, and a lack of leadership skills [2,9,30,32,47,51,52,58,66,68,70,73]. In human resources, reported challenges related to a lack of trust between private and public partners, ownership identity, disparities in power, and lack of capacity to undertake non-clinical tasks by staff in private clinical settings [9,15,32,38,42,47,51,54,57,61,67,68,70]. For financial resources, issues were rooted in inadequate and insecure funding, questions over the long-term sustainability of PPPs, lack of trust in the reimbursement system used by private partners, and not accounting for PPPs in annual budgeting process [9,15,28,31,40,42,43,49,51,59,62,67,68,70]. For information and technology systems, challenges originated from unclear policies and regulations regarding the implementation and evaluation of PPPs, problems with documentation and record-keeping in private sector providers, a weak capacity to collaborate between sectors or implement regulations, information gap and lack of standardisation, and lack of sufficient monitoring due to lack of defined indicators [8-11, 15, 35, 41, 46, 49, 51, 53, 56, 63, 67, 70]. Additional challenges arose from low efficiency of the private sector in taking care of the poorest strata of the population, as well as a lack of capacity of both sectors to engage with one another [10,15,46,68].
Studies also provided recommendations on how to overcome reported challenges and create effective partnerships (Table 3). For example, in education this can be done by ensuring that only most up-to-date and evidence-based treatment guidelines are used in both sectors, conducting sensitisation workshops based on needs assessment, as well as developing effective information, education and communication strategies for the communities [13,26,28,29,34,49,63,68]. In management, one could consider to streamline regular communication and coordination between collaborators, encourage commitment and engagement, ensure that there is appropriate legislation that supports the work of PPPs, clarify roles and responsibilities, set realistic goals and objectives, and ensure better coordination of collaboration [8,9,13,35,39,46,49,53,58,61]. In human resources, it is vital to facilitate good communication between all members of PPPs, encourage a positive attitude towards PPPs, bring strong stakeholders into partnerships, and create a culture of respect, appreciation, and trust [9, 31, 47, 51-53, 57, 74, 75]. For financial resources, it is important to introduce financial incentives, ensure funding sustainability, and identify alternate financial suppliers [6,28,36,56,59,69,74]. For information and technology systems, one should consider placing quality assurance mechanisms, building appropriate legislative frameworks, setting up monitoring and documentation systems, using digital tools, and strengthening information systems [6,9,13,15,20,54,59,61,63,75]. To support these efforts, it is important to have some flexibility in PPPs models and complement it by political and community support of PPPs [38,51,53,61,76].

Discussion
We examined the global experience of PHC provision via PPPs for basic PHC services, health education and promotion programs, and services for infectious diseases. The majority of PPPs projects facilitated education and health promotion initiatives and were used to increase access and to facilitate the provision of prevention and treatment services (i.e., TB, malaria, and HIV/AIDS) for certain target groups. The challenges of providing PHC via PPPs were reported primarily for the starting and implementation phases of project execution. Reported challenges and recommendations on how to overcome them fell into one of five areas: education, management, human resources, financial resources, and information systems.
To improve the health care delivery system and to overcome the limitations of financial, technical, and human resources aspects, PPPs should be considered for future health reforms [3,15,77]. Governments already see the potential for private sector involvement in improving public health and PHC services delivery [74,78],  [38,51] ▪ Insufficient knowledge of the private about testing and treatment procedures [51,56,61,67] Management ▪ Lack of commitment of public and private sector managers and decision-makers [9,51,52,58,73] ▪ Lack of clear vision on the way forward [68,70] ▪ Non-formulation of strategic direction for PPPs models by the government [70] ▪ Lack of accountability, poorly defined roles and lack of advisory committees [30,52] ▪ The difficulty of coordinating different members, especially in the early stages [47,66] ▪ Poor leadership skills [32] Human resource ▪ Lack of trust between the public and private sectors (9,47,54,57,70)s ▪ Disparities in power actors involved in partnership [15,32] ▪ Limited access to people willing and able to participate in the private sector [32,38] ▪ Lack of capacity of private practitioners and hospitals to undertake non-clinical tasks such as treatment supervision or prompt recording and reporting of required data [51,61,68] ▪ Lack of perceived ownership of the project by partners [42,61] ▪ Reported disrespect and distrust of the public sector towards partners from the private sector [9,67,70] Financial resources ▪ Downsizing of social capital [15] ▪ Inadequate financial resources [28,40,42,59,68] ▪ Sustainability of the PPPs [49] ▪ Insecure funding [31,68,70] ▪ Lack of trust by private sector partners at the reimbursement system [51,62] ▪ The unwillingness of the public sector to use financial incentives for private sector motivation [43,67] ▪ Not setting the specified budget for PPP [9] Information and technology systems ▪ A weakness of the private sector in the documentation of services provided by the private sector [34,35,41,49,51,53,56,63] ▪ Lack of consistent form of interaction between the public and private sectors due to different systems [9,15,51,67] ▪ Lack of appropriate monitoring and reporting mechanisms [9,15,49,67] ▪ Lack of clarity in policies regarding the implementation and evaluation of PPPs [15,46,70] ▪ Absence of support systems for supervision and record-keeping for private-sector employees [26,58] ▪ Inefficient administrative system [61,62] ▪ Weak capacity to collaborate or regulate [54,57,68,70]  ▪ Weakness in implementing regulations [68] ▪ Inadequate mechanisms to ensure continuity of care [68] ▪ Information gaps exist between public and private sector [10,40,57,67] ▪ Absence of external performance assessment of PPPs [10] ▪ Lack of standard internal monitoring system [10] ▪ Failure to define an indicator for evaluation of PPPs [8,9,11] Others ▪ Low efficiency of the private sector in taking care of the poorest sectors of society [15] ▪ The poor capacity of the public sector to design and manage contracts with private organisations [10,45,68] PPP Public-Private Partnership as they can bring benefits to the health care system, population health, and can lead to direct and indirect costs savings [79]. They also provide an opportunity for mutual learning between colleagues by stimulating the creation of new knowledge and infrastructure, increase transparency, which can provide greater accountability, public confidence, and result in a higher quality of care [75,76]. PPPs can lead to improvements in efficiency and effectiveness in service provision and provide a necessary platform for social tests that can enable learning, for example, on how to handle the most unsustainable health problems. However, the opponents of PPPs believe that most PPPs are weak, as developing countries do not have the resources to monitor the quality of provided health services [80,81]. Private medical providers are also accused of self-centred attitudes and noninterference in public works. However, some doctors working for the private sector might be willing to take part in partnerships to be able to fight TB and provide HIV/AIDS services for the target population together with the public sector employees and other health sector representatives. The role of private doctors also needs to be carefully analysed and should be supported in its processes when assuming responsibility as primary caregivers [61].
A partnership should not be formed unless the public sector is strong enough to ensure that it can provide appropriate training and health care services, monitor the outcomes, and have the ability to engage as a partner in PPPs [51]. Before designing any partnership, clear and achievable public interest goals should be considered. A Table 3 Recommendations for effective Public-Private Partnerships in Primary Healthcare Education ▪ Improving training of the private health practitioners based on the latest treatment guidelines [13,28,29,49,51,63] ▪ Ensuring the knowledge transfer of the most effective, latest and evidence-based treatment guidelines [29,39,47,49] ▪ Effective information, education and communication strategies in the community [26] ▪ Conducting sensitisation workshops [67] ▪ Conducting retraining courses during participation based on needs assessment [6,34] Management ▪ Choosing a strong interface to ensure coordination between partners [8,9,46,47,51,57,61,67] ▪ Organising regular meetings to maintain communication and to foster and coordinate plans [9,47,62] ▪ Creating more commitment among partners [13,21,26,47,49,51,53,58,61,62,64,70] ▪ Creation of a national policy document outlining schemes for PPP [61,70] ▪ Having a clear delegation of duties and creating process indicators for initiating and sustaining partnerships with private providers [20,30,35,53,58,61] ▪ Determining a shared vision, strong governance and effective management to achieve objectives [21,35,39,53,66,70] Human resources ▪ Creating good communication between all members of the PPPs [9,31,51,57,70] ▪ Taking concerns of all members in initial seriously [51] ▪ Encouraging positive attitudes towards the PPPs, particularly during the initial stages [51,53] ▪ Convincing the private sector that they will benefit from the PPPs [51,61] ▪ Creating change thinking among staff [5,9,67] ▪ Attracting strong stakeholders into the partnership [47,50,51,53,57] ▪ Facilitating respectful relations in the partnership [9,57,70] ▪ Appreciating the attitude and performance of the staff [31] ▪ Maintaining transparency between sectors to build trust [9,31,32,47,52,66,70] Financial resources ▪ Introducing financial incentives for private sector motivation [4,32,56,69] ▪ Ensuring availability of appropriate funds [6,28] ▪ Taking the determination of sustainable financing for partnership seriously [49,62] ▪ Identifying alternate financial suppliers [59] Information and technology systems ▪ Ensuring the existence of a quality assurance mechanism and program [6,13,20,54,59,70] ▪ Establishing norms [15,61] ▪ Tackling morality and accountability issues [15,51,65] ▪ Building a legislative framework [9,15,61,70] [8,15,27,58] ▪ Strengthening supervision of private sector [6,9,47,51,65] ▪ Setting a monitoring and documentation system for referrals [9,13,63] ▪ Strengthening the information system [39,57,67] ▪ Determining the appropriate referral structure [9,61,67] ▪ Using digital tools in facilitating project operations and also in ensuring adherence to protocols by both providers and patients [42,68] ▪ Ensuring continuity in care for patients by the strength of provider networks and determine policies and program actions [31,61] ▪ Establishing procedural requirement in getting the funds released timely for grant/reimbursement to the private partner [53] ▪ Creating a payment-based financial system [27,32,46,69] Others ▪ Ensuring flexibility of the PPPs model to adapt to changing circumstances [28,51] ▪ Encouraging political and community support for partnership [43,53,61,68] PPP Public-Private Partnership government structure should then ensure that the goals are in line with the needs of stakeholders in publicprivate partnerships, and tools and mechanisms to measure progress and success are well-defined [82]. All partners should also be motivated and provided with incentives to ensure active engagement and participation [9,51]. All individuals who participate in the partnership must have the appropriate level of bargaining power. Hence, to form a common attitude among all partners, sensitisation and persuasion training is also recommended [51,82]. Another important element is transparent communication and accountability of all partners [30,32,81].
PPPs can have a better and more stable performance by improving existing healthcare infrastructure, deploying trained human resources, and, most importantly, by better monitoring doctors and professionals and managed organisations [67]. Although the implementation of a PPP model is not easy, it could be even harder to maintain it [51]. Sustainability of participatory models is one of the important issues. A lack of financial support and commitment, especially at the level of top executives, are among the issues that can distort the model's sustainability [9,51,68]. Hence, the sustainability of each model of PPP depends on the ability, commitment, collaboration, and communication between the public and private sectors [9,32,51,70].
Additionally, long-term planning and sustainability policies should be considered, as well as any additional health care costs. Alternative and sustainable funding sources should be identified, and PPPs must be prepared to respond to possible problems, seize the opportunities, anticipate external threats, and be flexible. The weaknesses and deficiencies of any partner involved in PPPs could potentially affect the provision and quality of PHC services. However, ultimately, it is the government and local health authorities that are responsible for PHC services provision to the population [27,51,68,82].

Limitations
Our study is one of the first to review PHC services provision via PPPs. The key weaknesses of our review should, nonetheless, be kept in mind. First, our findings reflect the results of partnerships in PHC and left studies reporting on PPP use in hospitals and other healthcare sectors outside the scope of this review. Second, we only reviewed studies that were published in the English language, potentially leaving important studies reported and published in other languages.

Conclusion
Despite various challenges, PPPs could provide a good opportunity to facilitate access to health care services, especially in remote areas. However, it should be noted that the success of PPPs depends on the existence of transparency in relationships between partners, PPPs being flexible, having a sustainable financing source, mutual commitment, and the ability of the public sector to monitor and control the quality of services provided by the private sector. Therefore, governments should consider long-term plans and sustainable policies to start such partnerships and learn from the experience of other countries.