Primary health care in the Amazon and its potential impact on health inequities: a scoping review

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Introduction
Most of the Amazon region population living outside urban areas and big cities is subject to precarious living and health conditions. These circumstances result from how these people have been exploited over time, which generally demonstrate a disregard for their interests . Investments have been made in the Amazon region to expand large-scale livestock, soy production and extractive activities, such as logging, mining, oil and gas exploration and construction of hydroelectric plants, but, in general, these actions operate in an exploratory logic that, in addition to being harmful to the environment, violate local communities' rights .
The areas of environmental degradation 'coincide' with social degradation areas, which further exposes people to vulnerable situations and, consequently, health risks . The literature cites access to potable water, lack of basic sanitation, infectious diseases, exposure to toxic products, and high nutrition-related disease rates as common problems in this region .
These conditions are aggravated by the Amazon being marginalized by domestic policies of Amazonian countries, which exclude the region from national plans and dynamics . This situation contrasts with the importance of the Amazon on the global stage because it accounts for 56% of the world's rainforest and 20% of its freshwater flow.
The Amazon is in South America, covering an area of 6 million km in nine countries. Its coverage is distributed in those countries as follows: Brazil (58.4%), Peru (12.8%), Bolivia (7.7%), Colombia (7.1%), Venezuela (6.1%), Guyana (3.1%), Suriname (2.5%), French Guiana (1.4%), and Ecuador (1%) . It is characterized as a biome predominantly composed of forest located in the Amazon River's hydrographic basin. Despite that, the Amazon is not homogeneous but consists of different areas that result from the interaction of its physical aspects with the population diversity that inhabited this region at different times in history .
The literature shows how parts of the region gained importance because of the natural resources to be explored . This resulted in the occupation of the territory, which has contributed to the formation of large urban centers and places where a greater financial and political capital is concentrated in relation to most of the region, which consists of a mosaic of farms, villages, isolated houses and small towns spread over a vast territory, often accessible only by river, and that can be considered remote because of the difficult access. As a rule, these places are inhabited by Indigenous peoples. These peoples include a wide variety of groups, who, depending on where and how they live, are known as 'villagers', 'mestizos', 'river people' or 'caboclas' .
The historical development of this region and the transformations that it has undergone, also marked by inequalities in the distribution of power, prestige, and resources, has contributed to the presence of health inequities in the region, which can be observed in the lack of resources and public policies, including health policies, in areas outside the urban centers or that are not being economically explored. This reality has contributed to the limited access to health services, especially high-complexity services, that are usually offered in larger cities . In most South American countries, primary health care (PHC) has been strongly influenced by selective PHC models. In those countries, the vertical health programs focusing on specific diseases and not on the global needs of users were common between the 1980s and 1990s . One result of this process in health policy was to increase privatized services and adopt a market-oriented approach with minimal economic interventions targeted at specific groups . These policies have led to a general lack of support for a more comprehensive PHC model and have increased social inequities . It was common for the poorest and rural populations to be harmed in this model . The absence and difficulties of PHC performance in the Amazon causes concern because studies have found improvements in health indicators associated with the implementation of PHC .
Furthermore, in rural and remote areas, care recommended by PHC has been considered strategic to meet the needs of these territories . Its relevance in these locations is emphasized, given its importance for reducing morbidity and mortality . PHC is also considered ideal when caring for traditional populations in rural and remote areas .
Given the relevance of PHC in the Amazon and the difficulties of health policies to prove effective when facing this context , the aim of this review was to map the studies in the literature that have addressed these issues, identify the ways in which PHC is implemented, analyze its potential to reduce health inequities in locations outside urban areas in the Amazon, and identify gaps that can guide future research and help plan service improvements in this region.

Methods
Because of the complexity of the issue and that it has not been reviewed previously to any extent, this study adopted a scoping review methodology. By using the protocol proposed by Arksey and O'Malley , the main concepts of the area of study were mapped, and existing gaps in evidence were identified. The understanding gained from the mapped studies was then synthesized in accordance with the method described by Levac et al .
In view of the study objectives, this review proposed the following question: 'How does PHC function and what are its strategies in the Amazon and their respective potential to reduce inequities?'. In this study, the concept of PHC followed the approach defended by Vuori , which presents at least four ways of understanding PHC: as a set of activities, as a level of care, as a strategy of organization for the service system, and as a principle that should guide all the actions developed in a health system. The search keywords were identified, considering these statements.
The search keywords (Table 1)  The titles and information on the abstracts in these records were reviewed independently by two researchers; studies that did not meet the inclusion criteria or any of the established exclusion criteria were excluded (Table 2). Only studies published in peerreviewed journals were included. Where there was disagreement about eligibility, one of the authors who had not participated in the first phase of the review gave their opinion, and then the other authors reread the item, and the final decision on inclusion was made in a group meeting. Studies were not excluded on quality grounds but purposely included to map available evidence as consistent with the scoping review methodology.
After that, three authors read the complete articles and reviewed them independently. During this process, the reference lists of included studies were also evaluated, resulting in the selection of no additional studies. The authors created a spreadsheet model with predefined codes that was shared among reviewers for data extraction. During data charting, some codes were adjusted, and other codes were added to the spreadsheet. That resulted in the following information being collected for each article: author, year of study, objective, country, method, how rural is described, PHC strategy/actions, positive impacts, and negative impacts. Then, each article was summarized and classified according to content.
This process enabled visualization of the scope and discussion among the team, resolving any disagreements about content allocation. Following this, content analysis was performed in accordance with the theoretical reference used.

Ethics approval
Because this work was a literature review and relied on secondary materials, it did not require ethical review.

Results
The database search returned 817 results. Following the removal of duplicate articles, 378 unique records remained for possible inclusion in the review. Those papers abstracts were then read, leaving 81 studies for the researchers to read in their entirety and independently, after which 25 studies were included (Fig1). Table 3 shows the main characteristics of each included study.  Other terms used by authors to designate the place were 'Indigenous areas' (n=7), 'rural/remote' (n=3), and the 'region of the country' where the study took place (n=2); while other authors used characteristics to describe the place as a 'várzea region' (floodplain) (n=2). One of the studies that also referred to riverbank areas gave more emphasis to the aspects of the population groups that inhabited the place, referring to it as a 'fishing community' (n=1) and one of the studies referred to the place as 'interior' (n=1).

Implementation of actions and strategies adopted by primary health care
Of the 25 studies, 11 of them revealed promising results regarding PHC implementation and strategies. On the other hand, 14 studies presented results that highlight difficulties and challenges to be overcome .

Impacts on access
Based on the PHC actions implemented and their respective results in the studies (Table 3) Nine studies presented results that suggest positive impacts on the quality of services. Five of them referred to training or other strategies used to prepare the professionals , which resulted in qualified professionals to work. One of the studies dedicated to monitoring the activities and support to the professionals showed how these actions can contribute to improving the quality of care and the use of financial resources.
Four studies were addressed to investigated the adoption of culturally appropriate approaches by services and found facilitated ties with the community. One of the studies focused on the approach of implementing an STD/AIDS program in an Indigenous community and described the use of participatory methodology that avoiding a possible resistance to the program.

Impacts on community empowerment
Engaging community members in the construction of and decisionmaking for PHC actions appeared in one study that showed the participation of Indigenous health agents in both local health groups and regional health groups.

Discussion
The A common feature of the health posts is that they are located over scattered areas and serve a smaller number of people .
The actions and strategies of PHC, as well as the results, reveal that most of the PHC implementations face difficulties and challenges.
Nevertheless, some studies reported promising results and suggested that the strategies of PHC were effective in the Amazon region.
It is important to recognize the actions that have contributed to a better performance of PHC, as well as the strategies and actions that still present problems, both for the relevance that the PHC has in improving people's health conditions and for its role concerning health inequalities, since it is considered the most effective model in reducing health differences in society and in promoting equity . To achieve this result, the PHC must meet the following requirements: the PHC team should be highly accessible, and focus on high-quality and networked operations with other sectors to increase social cohesion and empowerment .

Previous studies have shown that improvement in access, in Latin
American countries, results in better health conditions. For example, a study conducted in rural areas of Bolivia reported that mortality rates were four times lower in areas assisted by PHC than in areas that did not receive assistance . Confirming those studies, the results of this review also showed positive impacts on rural Amazonian areas due to an improvement in access. Also, this review showed that the total number of PHC actions in the Amazon that had a positive impact on access was higher than those that had a negative impact.  Also of note in the findings is the gap in PHC actions that involved external partnerships in their implementation, which is understood to be essential for a less fragmented PHC that responds better to the inequities. This review also identified in PHC actions a lack of strategies aimed at modifying health determinants, which in this region primarily involve social and environmental issues. It is also of note that this review did not find evidence of any PHC strategies that demonstrated, prior to the service implementation, a concern with the impacts on inequities, a strategy that Freeman et al identified as significant when implementing PHC services.

Strengths and limitations
This scoping review is the first attempt to comprehensively

Conclusion
As an initial study exploring the existing literature about PHC in the Amazon, this review has produced useful findings. It has exposed forms of PHC implementation that appear to have promising results, indicating the paths to be followed by public health policies, health managers and professionals in the Amazon region.
The results highlight the benefits of actions that expanded access to PHC given their ability to adapt to the singularities of the place,

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The difficulties and challenges reveal that, despite the efforts of some Latin American countries to adopt comprehensive approaches in the training of professionals in academic courses, it is still necessary to strengthen public policies in this direction and prepare professionals to work in Amazonian areas. It must include training in approaches that promote the openness of these professionals to provide care that is culturally appropriate, comprehensive, holistic and accessible. Further to this, qualified managers are required to support and supervise the professionals. The review exposed gaps in the research that has been undertaken or at least published, including a lack of studies of strategies aimed at health determinants. There was also a lack of evidence of work involving community engagement and partnerships developed with other actors in the community. In this sense, there is an urgent demand for research and policies to prioritize these themes since they are fundamental strategies in the face of the threats to the health of people living in the Amazon.