【Abstract】 Background The hierarchical diagnosis and treatment system has become the top priority of deepening medical reform at present, and it is particularly important to understand its research hotspots and evolution.ObjectiveTo systematically summarize the development trend and evolution process of hierarchical diagnosis and treatment system in China and grasp its knowledge base, research hotspots and development trends, in order to provide scientific reference for subsequent research.Methods China National Knowledge Infrastructure(CNKI) database was used as the data source and "hierarchical diagnosis" "hierarchical treatment" "ladder network of medical prevention" "hierarchical medical system and division of labor in blocks" "hierarchical medical and service system and division of labor in blocks" "hierarchical medical system and division of labor" "initial diagnosis in community" "initial diagnosis at grassroots level" "treating acute and chronic diseases separately" "two-way referral" "cooperation between superior and subordinate medical institutions" "different division of labor in diagnosis" "different division of labor in treatment" "orderly medical diagnosis" "orderly medical treatment" "health service system+integration" "health service system+hierarchical" and "health service system+collaboration and division of labor" were used as key words to retrieve the documents related to the hierarchical diagnosis and treatment system in China from January to July in 2019.The retrieval time was from January 1, 1949 to July 31, 2019.Excel was used to retain and analyze the data, and descriptive statistical analysis was made on the authors, titles, document sources, publishing institutions, and volume of publications of the included documents.CiteSpace was used to obtain published journals, institutional cooperation and author distribution of the research results of China's hierarchical medical system.Through the analysis of high-frequency keywords, research hotspots were identified.Through time zone maps, clustering words and emergent words, the frontiers and development trends of the research were determined.Results In the end, 1233 articles were included, and the journal with the largest number of publications were Chinese General Practice〔287(23.28%)〕.The top five journals with the most published articles were all from the core database of Peking University Library(a total of 729 articles) with more than half of the total published articles.The institutions with high yield of research results were mainly centered around Huazhong University of Science and Technology, Capital Medical University, National Health Commission, Fudan University and Peking University.There were 68 core authors with a total of 457 articles, accounting for 37.28% of the total literature."Community health service" "medical alliance" "influencing factor" and "general practitioner" had always been hot topics in the research field of hierarchical diagnosis and treatment.The clustering labels of "patriotic health movement" "hospital bed" and "outpatient", and key words of "effect evaluation" "influencing factors" and "medical treatment" appeared from 1949 to 1978.The clustering labels of "medical treatment" and "medical insurance system", and key words of "community health service" "two-way referral" and "community health service institution" appeared from 1979 to 2008.The clustering labels of "grassroots medical and health institution" "combination of medical and nursing care" "medical service system" and "medical insurance", and key words of "medical service system" and "hierarchical diagnosis and treatment" appeared from 2009 to 2018.Conclusion The increase rate of literature of China's hierarchical diagnosis and treatment system is accelerated, but the quality of research results need to be further improved.There are a lot of cooperation among institutions, but the cooperation and communication among authors are limited, and no stable core author group has been formed.The research hotspots are gradually diversified and the research directions are continuously refined. How to find a new way of innovation from the institutional level through closer communication and collaboration is worthy of further study.

【Key words】Hierarchical diagnosis and treatment;Research hotspots;Research evolution;Bibliometrics

 

The hierarchical diagnosis and treatment system refers to the hierarchical of diseases according to the severity of diseases and the difficulty of treatment. Medical institutions of different levels undertake the treatment of different diseases, forming a diagnosis and treatment order of "primary treatment at the grassroots level, two-way referral, separation of urgent treatment and slow treatment, and linkage of upper and lower levels". Under the hierarchical diagnosis and treatment system, the general outpatient services, rehabilitation and nursing services undertaken by large and medium-sized hospitals are transferred to primary medical and health institutions, resulting in the decline of medical resources^[1]. The hierarchical diagnosis and treatment system is an important issue in deepening the medical reform in China. The implementation of this system is conducive to the maximum efficiency of the use of health resources, the refinement of patient services and the guarantee of everyone's access to basic medical services.

The system of hierarchical diagnosis and treatment has long been formed in foreign countries. The United Kingdom is one of the early representatives who strictly practiced the system of hierarchical diagnosis and treatment. The National Health Service Act was enacted in 1948 and the National Health Service (NHS) was established^[2]. The United States is the world's typical representative of medical marketization, effectively forming a hierarchical medical treatment model through the medical insurance system^[3]. Canada implements strict hierarchical diagnosis and treatment, and patients cannot go to secondary medical service institutions without the recommendation of family doctors^[4]. Chinese scholar Yang et al.^[5-6] published a series of literature on China's medical reform in the Lancet, pointing out that the disease spectrum in China has changed significantly in the past 30 years, from the former infectious diseases and perinatal diseases to chronic non-infectious diseases. The effective strategy to deal with the current situation is to establish a good hierarchical diagnosis and treatment system. Combined with the research results of many scholars, the General Office of the State Council issued the Guiding Opinions on Promoting the Construction of the Hierarchical Diagnosis and Treatment System in 2015 (Guo Ban Fa [2015] No. 70), which marked that the hierarchical diagnosis and treatment system officially became the most important starting point for deepening the medical reform and became the key to the success or failure of the new medical reform. Therefore, it is necessary to comprehensively grasp the past, present and future of the research on hierarchical medical system. Based on this, this paper, from the perspective of bibliometrics knowledge map, sorted out the journals and literatures in the research field of hierarchical diagnosis and treatment system, clarified the development trend and evolution process of the research, analyzed the research hot spots and cutting-edge research results in this field, and provided scientific reference for future research.

1       Materials and methods

1.1  Literature search

From January to July 2019, CNKI database will be used as the data source. The concept of the hierarchical system in the early call "ladder network of medical treatment, prevention and health care", 1954 years later changed to "blocks hierarchical division of medical service system", the eighteenth big used to call it the "community first option" first option "base layer" "two-way referral" “hierarchical health", after the new reform according to connotation points level diagnosis system is called" the first option at the grass-roots level, two-way referral, acute slow partition, the upper and lower linkage ", through literature reading, found "division of diagnosis and treatment" "division of medical" orderly "medical" orderly "diagnosis" "integration of medical service system" "medical treatment organization collaboration" similar to "hierarchical diagnosis and treatment". To sum up, in order to ensure the accuracy and comprehensiveness of literature retrieval, with "hierarchical diagnosis" "points level medical" "ladder medical prevention network" "blocks hierarchical division of medical system" "row area hierarchical division of medical service system" "hierarchical division of medical system" first option "community" "first option at the grass-roots level", "urgent slow divide and conquer" the "two-way referral" "the upper and lower linkage" "division of diagnosis and treatment" "division of medical" orderly "medical" "orderly clinical therapy" "health service + integrated" "+ hierarchical of health service system" "the medical treatment organization + collaboration" as the keyword search, retrieve the entry for "main topic", The retrieval time is set to 1949-01-01 to 2019-07-31.

1.2  Inclusion and exclusion criteria

Inclusion criteria :(1) literature related to hierarchical treatment system; (2) Literature is in Chinese; (3) Literature types are journal papers. In order to ensure the quality of research, journal sources are Science Citation Index (SCI), Engineering Index (EI), Chinese Core Keys General of Peking University, and Chinese Social Sciences Citation Index. CSSCI) and Chinese Science Citation Database (CSCD). Exclusion criteria: excluded newspapers, conference abstract literature, newspaper and periodical report literature, diagnosis and treatment guidelines, thematic discussion, exclusive interviews and abstract irregularities, invalid institutions, lack of authors, and literature unrelated to the research topic.

1.3 Literature screening, data extraction and quality assessment

Data were stored in RefWorks and Excel format, and literature was manually sorted and screened. During literature screening, the papers with the same name, author, journal and publication time were defined as repeated papers, which were combined into one included study. Replicative screening was performed by the investigator and checked two weeks later. After the articles are checked, literature screening is strictly carried out according to the inclusion criteria and exclusion criteria.For the controversial literatures, whether to be included or not is determined after discussion with relevant personnel.For the literature included in the study, the researchers extracted the article information and made further econometric analysis.

1.4Statistical Methods

Excel was used to retain and analyze the data, and descriptive statistical analysis was conducted on the information of the included literature, such as author, title, literature source, publication organization, publication volume, etc. Scientific knowledge map in literature metrology, information metrology and metrology is widely used in fields such as, not only can through the visual way to show a certain source of scientific knowledge in the field of research, development, knowledge architecture and research frontier of literature can be effectively mining hidden characteristics, patterns and trends, as the research in the field of a scientific knowledge to provide a unique perspective^[7].CiteSpace was prepared for America's Drexel University computing machines and information science beauty professor Chen information of visual software developed by using Java language, as the world's emerging scientific knowledge map drawing tools, in acquiring knowledge in the field of research foundation, research frontier and hot spots, analysis and research fields of scientific knowledge structure, insight into the evolution process, etc., have the computing power and force^[8]. Therefore, in this paper, RefWorks format data were imported into CiteSpace(version :5.3.R4.8.31.2018) for analysis to obtain the journals, institutional collaborations and author distribution of the research results of China's hierarchical medical system. Through the analysis of high-frequency keywords, the hot research areas are determined. Through time zone diagram, cluster words and emergent words, the research frontiers and development trends were determined.

2       Results

2.1 Literature retrieval results

At first, 1685 records were retrieved from the database, and 452 literatures were removed by the literature de-merging and inclusion and exclusion criteria, finally 1233 valid literatures were obtained.

2.2 Publication time and quantity distribution of included literatures

After sorting out 1233 literatures, the detailed number and growth trend of literatures on the research of China's hierarchical medical system from 1949 to 2019 were obtained, and the cumulative number of literatures increased in the form of approximate exponents over time. Among them, the number of published articles from 1949 to 1978 was less, with a total of 19. From 1979 to 2008, the number of papers published showed an increasing trend (from 1 to 30), and 142 papers were published in total. From 2009 to 2018, the number of papers published increased rapidly (from 48 to 233), with a total of 992 papers published (Figure 1).

2.3 Distribution of published journals, cooperative institutions and authors on the research of China's hierarchical medical system

2.3.1 Distribution of published journals on the research of China's hierarchical medical system

The top 5 journals in the list of published articles were: Chinese General Practice (287 articles, 23.28%), Chinese Hospital Management (137 articles, 11.11%), Chinese Health Economy (126 articles, 10.22%), Chinese Health Service Management (98 articles, 7.95%), and Health Economy Research (81 articles, 6.57%). Among the top 15 published journals, 9 journals belong to the source journals of Peking University's Chinese Core Periodical Contents, 4 journals are from CSCD, 2 journals are from the database of Japan Agency for the Promotion of Science and Technology (JST), and no CSSCI. The top 5 journals were all from the General Catalogue of Chinese Core Journals of Peking University, with a total of 729 articles published, more than half of the total (Table 1).

 

Table 1 Distribution of source journals on hierarchical diagnosis and treatment system in China from 1949 to 2019(top 15)

Note: Core of Peking University=General Overview of Chinese Core Keys of Peking University, CSCD=Chinese Science Citation Database, JST=Japan Science Technology Corportion

 

2.3.2 Distribution of cooperation institutions in China's hierarchical medical system research

The refining statistics of 1233 literatures were carried out according to the sources of research institutions, and the data was imported into CiteSpace software. Institutions in Node Types were selected, Pathfinder algorithm was selected, and other options were set as the default. In the output results, the circular coverage area (represented by the font size of the research institution) represents the occurrence frequency of the author's signature institution. The larger the area, the higher the occurrence frequency. The lines between the circles represent the cooperation between institutions. The lines are directly proportional to the frequency of cooperation, and the line nodes are the cooperation centers.

The hierarchical system in the country study the distribution of productive organizations, mainly including Agencies group 1: Huazhong university of science and technology, Tongji medical college medical institute of medicine health management as the core, and has cooperation withthe humanities and social science in Hubei province key research base of rural health services research center, Nanjing institute of major medical study medicine administration, according to the righteous medical school, school of management, Hubei university of political science and law and public management institute, China university of science and technology in school of economics, Huazhong university of science and health policy and management research institute (think-tank), Shenzhen Guangming New District Gongming Hospital, School of International Medicine, China Pharmaceutical University, etc..Agencies group 2:School of Health Management and Education, Capital Medical University and Health Development Research Center of the former National Health and Family Planning Commission as the core, and has cooperation withthe National health committee, the original Beijing Municipal Commission of Health and Family Planning, the original Health and Family Planning Commission of Heilongjiang Province, the original Health and Family Planning Commission of Heilongjiang Province, School of Public Administration, RenMinUniversity of China, Beijing DitanHospital, Beijing Children's Hospital, Capital Medical Universit, Beijing Xicheng District Community Health Service Management Center, Weifang Medical UniversitySchoolOf Public Health, YouJiangMedical UniversityforNationalities, Chinese Academy of Medical Sciences Institute of Medical Information, andsoon. Institutional Cooperation Group 3: With School of Social Development and Public Policy of Fudan University as the core, cooperated with School of Public Health of Fudan University and former Health and Family Planning Commission of Changning District, Shanghai, etc. Institutional Cooperation Group 4: China Health Development Research Center of Peking University asthe core, and has cooperated with School of Public Health of Peking University, etc. (Figure 2).

2.3.3 Distribution of authors in the study of China's hierarchical medical system

The refining statistics of 1233 literatures were conducted according to the core authors and the cooperation between authors. Data was imported into CiteSpace software, Author in Node Types was selected, Pathfinder was selected by the algorithm, and other options were set as the default. The results of the core authors (the first 22) are shown in Table 2, and the cooperation among authors is shown in Figure 3.

Due to the limitation of software function, the published statistics of authors cannot be identified as the corresponding author or the first author for the time being. Therefore, there may be cumulative studies in the research field of the hierarchical diagnosis and treatment system in which the author has published articles other than the corresponding author or the first author. Statistical analysis showed that the cumulative number of papers published by the most scholars was 26. According to the "square root law" proposed by Price, the number of core authors in a research field can be determined. The formula is:N=0.749×nmax

Table 2 Distribution of core authors of the study on hierarchical diagnosis and treatment system in China from 1949 to 2019(top 22)

 

2.4 Research hotspots of China's hierarchical medical system

The research hotspot is usually the common concern of the closely related and numerous literatures in a certain period of time. Key words are the author's highly condensed research content, which can well reflect the core content of the article. Therefore, through the statistical analysis of the frequency of the occurrence of key words, we can well grasp the research hot spots in this field.^[10]Review found that couplet of "medical" and "medical association", "impact factor" and "factor analysis" as a concept, the number of high frequency can be stacked, so, after finishing the data import CiteSpace software, select the Node type (Node Types) of keyword (Key word), algorithm selection Pathfinder and Pruning sliced networks, and other options in accordance with the default Settings. The hot point knowledge map of China's hierarchical diagnosis and treatment system was obtained. The larger the font in the map, the higher the frequency of the keyword.The results showed that the top five keywords were community health service (364 times), influencing factors (337 times), medical confederation (243 times), general practitioner (185 times), and effect evaluation (152 times).In terms of centrality value, the top five centrality were "community health services" (0.24), "medical confederacy" (0.22), "influencing factors" (0.19), "medical insurance" (0.13) and "general practitioner" (0.12), besides "hierarchical diagnosis and treatment" and "two-way referral", which were the strongest research topics.In terms of outbreak points, the top five hot spots were "influencing factors" (69.59), "community health services" (42.28), "effect evaluation" (37.29), "general practitioners"(28.58), and"medical association" (10.15).Thus, "community health services", "medical confederacy", "influencing factors" and "general practitioners" have always been hot terms in the research field of hierarchical diagnosis and treatment (Figure 4).

It is important to note that the sequence and the sequence of the centricity can be found by comparing the keywords, the sequence of the part of the word frequency is not high but the sequence of the centricity is higher, mainly for: "medical service system", "diabetes" "medical resources" "primary health care, " "family doctor service contract", "healthy China" shows that a lot of research around the health under the background of China, the family doctor to sign, chronic diseases, between the hospital and community medical institution reform research.

2.5 Evolution of China's hierarchical medical system

To overall analysis our country the hierarchical system research in the field of knowledge base structure and the evolution process, in this paper, the Time in a 1233 documentary by CiteSpace software - zone view, select 10 years as a Time section display keywords network node the structural relationships change over Time, and according to the automatic clustering graph clustering algorithm, using the logarithmic likelihood ratio algorithm to extract clustering tags, and the top 10 emergence nouns.

The results show that "patriotic health movement", "bed" and "outpatient" cluster labels appeared from 1949 to 1978. From 1979 to 2008, "medical treatment" and "medical insurance system" cluster labels appeared. From 2009 to 2018, "primary medical and health institutions", "combination of medical and nursing care", "medical service system" and "medical insurance" cluster labels appeared (Figure 5). From 1949 to 1978, the key words "effect evaluation", "influencing factors" and "medical treatment" appeared. From 1979 to 2008, "patient", "community health service", "two-way referral" and "community health service institution" appeared. From 2009 to 2018, "hierarchical medical care", "medical service system" and "hierarchical diagnosis and treatment" appeared (Figure 6).

3 Discuss

3.1 Research literature characteristics analysis of China's hierarchical medical system

Combined with the changes of China's social and economic system, medical service system and the implementation of relevant policies, it can be divided into three stages. (1) Initial exploration stage (1949-1978): This stage was the planned economy period at the beginning of the founding of the People's Republic of China. The country implemented the "medical service system based on regional division of labor" and initially formed the hierarchical diagnosis and treatment pattern. However, there were few relevant literatures, with an average of no more than one paper per year. (2) Stable rise stage (1979-2008): This stage was from the early stage of China's reform and opening up to the early stage of the new medical reform. China's hierarchical diagnosis and treatment experienced a process from becoming loose to re-exploring and returning. Therefore, the number of relevant research literatures increased year by year and showed a steady rise trend, reaching a peak of 30 in 2008. (3)Rapid development stage (2009-present): After the new medical reform in 2009, the government put forward the importance of hierarchical diagnosis and treatment again, and took it as an important push to deepen medical reform in 2015. Therefore, the number of literatures at this stage showed a rapid rise. Especially after 2015, the number of articles published each year was basically maintained at more than 100, and the annual average number of articles was 185.

3.2 Analysis of high-yield journals, institutional cooperation and author distribution in China's hierarchical medical system

In terms of the distribution of high-yield journals, although the journals in their research fields have disadvantages in academic circles, it also reflects to some extent that the research results of hierarchical diagnosis and treatment in China need to be further strengthened and improved.

Look from distribution agencies, the health administrative organization (government actors) and government research institutions, medical institutions, schoolsresearch institution, interest groups (health services organizations, such as hospitals, community health service centers) actively involved in the hierarchical system research, and constitute the main body of research in colleges and universities, academic cooperation broke the traditional disciplinary boundaries, to promote the progress and development of the hierarchical system research.

Core author refers to a scholar who has great influence and plays an important role in a certain research field. Scientific research is often a team activity, and most articles are completed through collaboration among authors. Authors learn from each other's strengths to improve the depth and breadth of research.^[11] Therefore, it is very important to analyze the distribution of cooperation between the core authors of the literature.According to the statistical results, the total number of core authors is less than half of the total number of papers, it can be concluded that China has not formed a stable core group of authors in the research field of the hierarchical diagnosis and treatment system.

From the perspective of the distribution of cooperation among authors, the cooperation and communication among the authors of the research on the system of hierarchical diagnosis and treatment is relatively limited, and the cooperative groups formed are more frequent within the group and less among the groups, which is not conducive to the improvement of the research level of hierarchical diagnosis and treatment, which may be related to the different research points of different authors. At present, a group of authors with Zhang Liang, Fang Pengqian, Lu Zuxun, Wang Chaoxin, Zhuo Lang and Liang Hong as the core has been formed in domestic research. Zhang Liang's team from the School of Health Management, Tongji Medical College of Huazhong University of Science and Technology mostly studies the hierarchical diagnosis and treatment system from the perspective of township and county medical institutions. Fang Pengqian's team from the Institute of Health Policy and Management of Huazhong University of Science and Technology mainly studied the hierarchical diagnosis and treatment system from the perspective of medical association, "three-medical linkage" and public hospitals. Lu Zu Xun's team from the School of Public Health, Tongji Medical College, Huazhong University of Science and Technology (HUST) mainly discusses from the perspective of "community first diagnosis".

Wang ChaoxinfromTongji university school of medicinehas cooperation with both research network, one is with Luoli, Baige and Zhang tian-tian from Fudan university school of public health, focused on clinics, rehabilitation and long-term care shunt hierarchical diagnosis and related studies.

The other is the cooperation with the affiliated hospital of Tongji University, mainly studying the status quo of bidirectional referral criteria for hypertension, the systematic evaluation of the status quo ofhierarchicaldiagnosis and treatment in Shanghai and explore the three-dimensional collaborative mode of regional health based on hierarchical diagnosis and treatment.Zhuo Lang from Xuzhou Medical University and other researchers mainly studied hierarchical diagnosis and treatment from the awareness rate and willingness of residents (demanders) in Xuzhou. Liang Hong's team from the School of Social Development and Public Policy of Fudan University conducted research from the perspectives of "medical association" and "contract system of family doctors".

3.3 Evolution analysis of China's hierarchical medical system

According to the above three development stages (initial exploration stage, steady rise stage, and rapid development stage), and the analysis of the key node literature, influential literature, published authors and other information in each stage, the research evolution and development trend of this research field in the past 70 years can be revealed.

3.3.1 Initial Exploration Stage (1949-1978)

In the early days after the founding of the People's Republic of China, the state put forward the "ladder medical prevention network", which was later the "medical service system based on district division and division of labor", which was adopted at the National Health Conference in 1956 after being tested in some provinces and cities.This system is mainly for the convenience of the masses to go to a doctor nearby, to overcome the crowded and busy phenomenon of large hospitals and improve the quality of medical treatment, through the unified layout planning, the province, city, county (district) three level hospitals and grass-roots medical and health institutions organically constitute the medical and health network, according to the regional hierarchical division of labor and business guidance contact. Countries in this time period also released the measures for the implementation of the national worker medical treatment to prevent (1952), the Ministry of Finance, the ministry of health on consolidation and strengthening medical treatment management work notice (1978), the articles of association of rural cooperative medical care system (1979), such as file requirements shall, first of all, in the patients with medical institutions, adhere to strict referral program, without approval and referral referrals, unable to get the reimbursement. The government has set up a three-tier medical system in urban and rural areas. The health care system is centered on "primary health care". The health care system is fully funded by the government, and the government implements the public health care system for government organs and public institutions, the enterprise labor insurance medical system, and the rural cooperative medical system. ^[12] During this period, "blocks hierarchical division of medical service system" and the planned economy system, under the condition of the weak economy, through three more strict control of medical treatment insurance, under the condition of ensure the basic medical services a "specified type to see a doctor", promote the vaccine to eliminate pests, in order to control the disease such as smallpox, malaria, schistosomiasis, quickly improve the health level of the masses, form a pattern of essentially the hierarchical of diagnosis and treatment, known by the world health organization (who) as the model of medical and health system.^[13]

Stage of the academics around the effect of "blocks hierarchical division of medical service system", solve the problem of outpatient crowded, how to do a good job of prevention and management under the system of "socialized medicine" to save medical resources, avoid the waste of medical insurance funds aspects are studied, thus the dash forward show the noun "influencing factors", "performance evaluation" clustering words "patriotic health campaign" "bed" "outpatients.The Cai Hengfang^[14] is introduced using scribing point of Beijing, reorganization of medical institutions, to set up similar couplet of the medical model of medical institutions between the superior and the subordinate business leadership, we must adjust the relationship between health and propaganda education way to carry out the hierarchical division of medical treatment, can solve the problem of uneven hospital busy idle, to facilitate the masses to go to a doctor, improving medical technology level, promote the purpose of prevention work.LiuShao-zhu^[15]put forward "three long and one short" problem should be deal with hospital executive blocks hierarchical division of the medical system to improve the medical order, and to all levels of different kinds of tasks should be different and collaboration with each other, form an organic whole, help grassroots health institutions will assume the task of common frequently-occurring disease, convenient to the masses, to the nearest according to undergo, alleviate the problem of large hospital outpatient medical consultations.Sun Jiaxian^[16]consider that in Heilongjiang province after the implementation of "blocks hierarchical division of medical service system", is beneficial to improve the level of hospital management and medical quality, to give full play to the potential factory enterprise systems such as hospital, to establish policy of medical order and step by step business technical guidance, to mobilize the enthusiasm of the grassroots health institutions, put forward the system can be implemented in the country and shall establish the national medical college center, establish the national urban and rural medical and health web.In order to solve the problem of overspending on public health care, Huang Yun^[17] believed that the main reason is that there are deficiencies in management, such as lax control of treatment, referral and reimbursement procedures, and that medical institutions do not grasp the principles of treatment, leading to the occurrence of more prescriptions and more inspections.Liu Ruiqing^[18] believes that the "partition package, classification of responsibility", which not only ensures the treatment and can overcome the problem of medical institutions just treatment regardless of saving, strict implementation of hospitalization, hospital transfer, hospitalization system to reduce unnecessary medical costs, strict investigation of the side and financial accounts, etc.Hua Ying^[19] pointed out that preventive health care is the most effective way to save medical costs, and management, treatment and health care should be combined. Patients who need to be referred should go to a designated hospital for treatment, and patients who need to be referred should have a letter of referral before reimbursing medical expenses.From 1949 to 1978, the practice of medical confederacy had been established, and some scholars proposed to establish several specialized medical centers throughout the country. However, in general, there were not many research achievements in this field during this period, and it has not been widely concerned by researchers.

3.3.2 Stable rising stage (1979-2008)

During this period, from China's reform and opening up to the early stage of the implementation of the new medical reform, the hierarchical diagnosis and treatment system experienced a process from loosening to being reexplored. The market-oriented transformation of China's social and economic system has promoted the market-oriented transformation of the medical and health system, and the hierarchical diagnosis and treatment model has been impacted. Under the competition mode, hospitals are getting stronger and stronger due to the more resources they occupy, the function orientation is gradually blurred, and the service ability of primary medical and health institutions is gradually reduced. The economic recovery has released people's demand for medical services, and the reconstruction of the three major medical insurance systems has increased patients' choice of medical treatment, prompting patients to flock to large hospitals, forming a "free choice" medical treatment mode. The hierarchical diagnosis and treatment pattern has been completely broken, and the flow of medical treatment presents an "inverted pyramid" pattern. With the increasingly prominent problems of difficult and expensive access to medical services, the poor performance of the market-oriented reform of the medical system and the serious problems of disordered medical treatment, the state began to pay attention to the construction of primary medical care. In 1999, the former Ministry of Health issued Several Opinions on the Development of Urban Community Health Services (Weiji Women [1999] No. 326), which put forward the guideline of strengthening the capacity building of primary medical services. In 2006, the State Council promulgated the Guiding Opinions of the State Council on the Development of Urban Community Health Services (Guo Fa [2006] No. 10), which proposed for the first time in the state document to "establish a system of hierarchical medical treatment and two-way referral, and explore the pilot of community first-visit system". In 2007, as the former Ministry of Health launched the two-way referral hierarchical diagnosis and treatment system to alleviate the problem of difficult and expensive medical treatment, the idea of hierarchical diagnosis and treatment became clear ^[12-13].

At this stage, the number of research results began to increase gradually, reaching 30 by 2008, and the research in this field began to become active. At this stage, scholars mainly focus on the research on whether the "medical service system of zoning and grading division of labor" is in line with the current stage of development, the hierarchical management and evaluation of hospitals, the construction of medical confederacy, the new three major medical insurance, and the research on community medical institutions and two-way referral after re-exploration. Because of this, the key node of "two-way referral" and the cluster words of "community health service" and "medical insurance system" appear. In terms of research methods, they mainly focus on theoretical discussion, questionnaire survey, interview, empirical analysis and descriptive statistics.

With the convening of the Third Plenary Session of the Eleventh Central Committee in December 1978, China established the development direction of economic construction as the center, and the medical and health field also moved toward marketization, and the "medical service system of zoning and grading division of labor" had some contradictions with the current development. In 1984, Zhou Shouqi^[20] published the article "Question on Medical Service in Zoned Areas", which affirmed the positive role of the zoned medical service system with hierarchical division of labor, but also pointed out its existing contradictions: with the improvement of people's living standards, the demand for preferential medical treatment increases; Competitive pressure is beneficial to the improvement of medical level of medical institutions, so the autonomy of medical treatment units should be opened up. Nearby medical treatment rather than zoned medical treatment can be more convenient for people to see a doctor; With the increase of specialized demand, many patients cannot be covered "systematically and comprehensively" by zoned hospitals. The basic reason is that the "medical service system based on division of labor by district and level" does not adapt to the development of social demand at the present stage, so necessary adjustment and reform should be carried out. The author believes that a more flexible hierarchical form of "selective medical treatment" can be realized from the aspects of public opinion survey, developing its own technical characteristics, and carrying out two-way referral. During this period, all kinds of medical couplet body construction began to flourish, LiuTie-jun^[21]use"xiao cui find diagnosis" as a guide, put forward implementation steps, the medical care system is the necessity of couplet of "medical" construction, through the large hospital and small and medium-sized hospital established cooperation relations, not only will bypass patients, alleviate the pressure of the large hospital beds tight, also make the small and medium-sized hospital doctors medical technology level, incalculable to the promotion of social benefit.HuaZu-xing^[22] pointed out such as Shenyang in 1984 created the first "consortium", becausethe medical association has the advantages of voluntary combination, flexible cooperation mode and so on,  by the year 1988 has developed 238 (including 35 and other provinces and cities). While " medical treatment alliance " has brought benefits in various aspects, some problems such as blind association, simple pursuit of economic benefits and disguised charge for improper examination have also appeared.At the same time, he believed that the existing loose type of medical confederations with technical cooperation as the main body will transition and develop into intensive medical groups, from technical cooperation to entity joint management.In June 1989, Zhou Qi^[23] published "On the Implementation of Hospital Evaluation and Hierarchical Management System" in Management World. He proposed that, based on the experience of foreign advanced developed countries and China's national conditions, hospitals should implement a hierarchical management system, which could be divided into three levels corresponding to the corresponding institutions, functions and tasks.In November the same year the ministry of health issued "hospital classification management method (trial draft), the hospital according to the function, task, facilities, technology and medical quality integrated level is divided into three ten hierarchical management etc., the ministry of health issued"planning and guiding principles of the establishment of medical institutions"in 1994, put forward to set up the levels clear, structure is reasonable, function in three level hospitals, set up suitable for the situation of medical and two-way referral framework.During this period, a large number of articles on hospital hierarchical management and evaluation have also emerged. Since 1998, China's medical security system has undergone great reform. The basic medical insurance system for urban employees (1998), the new rural cooperative medical system (2003) and the basic medical insurance system for urban residents (2007) have been established successively.Tan Shen-sheng^[24] believes that with the deepening of the reform of the urban medical insurance system, the autonomy of the masses in medical treatment is released, which leads to the flow of patients to large hospitals, leading to overcrowding in large hospitals while small hospitals are deserted. Community health services should be vigorously developed to provide convenient, continuous, comprehensive, coordinated and cheap health services.Analysis from the perspective of literature cited frequency, the highest amount of the citedwas Li Xiaoxiao^[25] from Renaissance hospital affiliated to the capital university of medical sciences, published in the Chinese General Practiceof "The problems and countermeasures of dual referral system in China", in contrast to foreign two-way referral implementation present situation, proposed our country two-way referral is the easy to the difficult, lack of referral standards, incentive and constraint mechanism, market economic system under the conflict of economic interests, community hospital service ability is weak, the information sharing between the difficult problems, such as medical institutions.Followed by Qi Xiaolin^[26]from health management and policy research center of Shandong university published "On obstacle and countermeasure of community health services in China". She believed that China's community health services were still in the primary stage, and there were still some problems, such as the uncoordinated technical level of general practitioners, the incomplete "six-in-one" function, and the imperfect two-way referral system, compensation mechanism and medical insurance system.

3.3.3 Rapid development stage (2009 to present)

In April 2009, the CPC Central Committee and the State Council issued the Opinions on Deepening the Reform of the Medical and Health System (Zhongfa [2009] No. 6) to start a new round of medical reform, which defined the policy framework of hierarchical diagnosis and treatment. In 2014, Premier Li Keqiang proposed to improve the hierarchical diagnosis and treatment system, strengthen the training of general practitioners, promote the practice of doctors in multiple locations, so that the public can enjoy quality medical services nearby. However, due to the impact of two lines of income and expenditure, unreasonable performance-based pay, drug allocation restrictions and other factors, the implementation of the hierarchical diagnosis and treatment system has little effect.^[12-13] In September 2015, the State Council general office issued the guidelines on promoting the construction of the hierarchical system "(Issued by the State Council Office [2015] NO.70), points out that to establish the hierarchical system is deepening medical and health system reform, to establish an important content of basic medical and health care system with Chinese characteristics, has been clear about the evaluation standard and the 2020 goals in 2017.In 2016, the National Health and Family Planning Commission issued the Notice on the Pilot Work of the Hierarchical Diagnosis and Treatment of Hypertension and Diabetes (No. 1026 [2015] of the National Health Office), which defined the key tasks of the hierarchical diagnosis and treatment of hypertension and diabetes, and regarded its prevention and management as the breakthrough point to promote the establishment of a new hierarchical diagnosis and treatment mode.In August 2016, the CPC Central Committee and the State Council held the first National Conference on Health and Health since the 21st century, and the hierarchical diagnosis and treatment system ranked first among the five basic medical and health systems.In April 2017, the General Office of the State Council issued the Guiding Opinions on Promoting the Construction and Development of Medical Consortium (Issued by the State Council Office [2017] No. 32), making it clear that by the end of 2017, all tertiary hospitals in China will participate in the construction of medical consortium. By the end of 2020, all secondary hospitals and government-run primary medical and health institutions will participate in the medical association.^[12-13]

At this stage, the academic community has increasingly in-depth research on the system of hierarchical diagnosis and treatment. The number of journals published has increased from 48 in 2009 to 233 in 2018, with a nearly five-fold increase. Especially after 2015, the annual research results have exceeded 100, which is related to the fact that the hierarchical diagnosis and treatment has become the key to the success or failure of the new medical reform and has been attached great importance to at the national level."Combination of medical care", "basic health care mechanism" and "medical service system" are cluster words in this stage. A medical and health service system with clear functional orientation and good cooperative relationship among institutions is the basis for realizing hierarchical diagnosis and treatment.In order to effectively deal with the aging problem, the combination of medical care and nursing care must be supported by the hierarchical diagnosis and treatment. One of the key points of the success of the hierarchical diagnosis and treatment is whether the grassroots health service institutions can be revitalized.Have sprung up in this stage, from the planned behavior theory, signal theory, system theory, grounded theory, the social division of labor theory, stakeholder theory, game theory and the theory of incentive compatibility, integration theory, bilateral matching theory, platform, the Angle of theory, the expectancy theory of couplet of hierarchical diagnosis and treatment of medical doctor two-way referral behavior, family doctor contract mechanism, and two-way referral factors such as research.Look from the research content, main from the supplier (medical institutions), the buyer (patients, the masses) satisfaction, recognition and its influencing factors, couplet of implementation path exploration, especially in medical, family doctors to sign pattern more in-depth research, comparison of diagnosis and treatment system at home and abroad, discusses hierarchical diagnosis and to study the related system and mechanism to build relationship;In terms of research methods, it is no longer limited to using questionnaire survey, interview, empirical analysis, descriptive statistics and other methods, but also adds operational research, econometrics and other management engineering methods. In general, this period is more diversified in terms of research theory, research content and research methods.

From the perspective of the literature cited frequency, cited the highest amount is FuQiang^[27] at the National institutes of health committee of the hospital management in 2016, published in the Chinese Health Economics titled “Strategic choice for promoting hierarchical treatment model”, the paper published since the end of July 2019 were cited 178 times, the inductive hierarchical system in foreign countries mainly in a strict legal restriction, health service system that can meet the needs of relying on, clear family and specialist professional orientation, strict controls of diagnosis and treatment cost measures four characteristics of strong, proposed our country establish hierarchical diagnosis system is developed with focus on "at the grass-roots level to" "can health care expenses" "patients really benefit" three key issues, namely solve the problem of better medical services, especially basic medical service supply and perfect related health insurance and medical management policy to effectively guide and promote medical service;

The second is Huang Bei^[28], from the outpatient department of Wuxi Second People's Hospital, whosepaper“Practice and consideration on three types of medical alliance modes” published in Chinese Hospital Management in 2015, which was cited for 147 times. Among the six regional medical confederations in Wuxi City, the medical confederations of Wuxi Second Hospital developed the earliest (from 2009 to 2014, it was a loose regional medical confederations, and from 2015 to now, it has been exploring a tight medical confederations), with relatively mature operation.

The article described the author through to the Wuhan Fifth Hospital, Shanghai Jiao Tong University School of Medicine Affiliated Ruijin Hospital, Wuxi Second People's Hospitalmedical treatment alliance field interview and questionnaire survey, respectively from the aspects of management system, running mechanism, and the results of three different types of couplet of medical mode, found the three hospitals all believed that community first treatment and two-way referral should be carried out. It was pointed out that the appropriate type should be selected according to the specific situation. The tight type direct regulation should be the first choice if the relationship is relatively simple in the medical association, and the loose type should be tried first if the relationship is complex.

From the perspective of the number of papers published by authors, the top three were Zhang Liang (24 papers, Huazhong University of Science and Technology), Fang Peng-qian (15 papers, Huazhong University of Science and Technology), and Feng Ze-yong (13 papers, Chongqing Medical University).This stage Zhang Liang mainly focus in the counties and townships on the two levels of medical service system, by using the theory of integration, system thinking, collaborative division of labor theory and stakeholder theory of interaction between the levels of medical institutions, hierarchical diagnosis and "joining together of two insurance" policy, classifying medical connotation and essential elements, the key role of collaboration between counties and townships, counties and townships medical service integration mechanism is studied.

Fang Peng-qian mainly focus in public hospitals, using game theory and stakeholder theory to analyze the construction of hierarchical diagnosis and treatment service system and the first diagnosis at the grassroots level.It is the first time to build a comprehensive hierarchical diagnosis and treatment evaluation system, to discuss the construction of China's medical service system from the perspective of foreign experience and China's county classification, and to consider the relationship between "Medical care, medicine and medical insurance are interconnected", hierarchical diagnosis and treatmentand medical confederation.Feng Ze-yong mainly studies the relationship, influence and effect between two-way referral, community first diagnosis and the multi-site practice of doctors, essential medicine system, medical insurance system and other related systems.

4 Conclusion

4.1 The increase speed of the number of literatures is accelerated, but the research results need to be further improved

1949-2019, our country the hierarchical system overall present a trend of increasing number of research in the field of literature, presents the blowout growth since 2015, the main and countries since 2015 to the hierarchical system as an important driving force of deepening reform and intensify efforts to promote, as the "healthy China 2030" plan is put forward, and the hierarchical system will be the key reform direction in the future, is also much starker choices-and graver consequences-in planning a system comprehensive strategic deployment, the hierarchical system of related research number will be showed a trend of sustained and rapid growth in the next ten years.Among SCI sources, EI sources, Peking University Chinese core journals, CSSCI and CSCD journals, more than half of the research results are from Peking University Chinese core journals, which to some extent reflects the need to further strengthen and improve the authority and influence of the research results of China's hierarchical medical system.

4.2 There is a lot of cooperation among institutions, but the cooperation and communication among authors is limited, and no stable core group of authors has been formed

The hierarchical system research field in our country Formed the four major institutions of cooperation, although less communication between agencies group, but in college as the main body, cross-regional and health administrative organization (government actors) and the government research institutes, medical research institutions such as the cooperation and communication of broke the traditional disciplinary boundaries, benefit to the progress of the hierarchical system research and development; At present, a group of authors with Zhang Liang, Fang Pengqian, Lu Zuxun, Wang Chaoxin, Zhuo Lang and Liang Hong as the core is basically formed in the domestic research. The cooperation within the group is mostly in the mode of tutor-guided cooperation. The cooperation and communication among the authors is relatively loose, and the region is limited to Hubei Province, Shanghai and Xuzhou City, with less cross-regional cooperation. The total number of published papers by core authors calculated by Price's law accounts for less than half of the total number of literatures, indicating that a stable core group of authors has not been formed in the research field of hierarchical diagnosis and treatment in China.

4.3 Research hotspots are gradually diversified and research directions are continuously refined

From the point of the evolution, hierarchical system of diagnosis and treatment of research in China has experienced the planned economy period in the three major health care under the control of "blocks hierarchical division of medical service system", appeared in the early years of the reform and opening up loose and new exploration period, the new health care reform is put forward with the period a total of three stages, after a "community health service" couplet of "medical" "impact factor" "all-around doctor" "effect appraisal" hot word "medical service system" and so on and highlight the key words, the research direction is more diverse, refining, there are a lot of groundbreaking research.

4.4 Future Prospects

In general, the hierarchical diagnosis and treatment system has experienced nearly 70 years of evolution and has attracted great attention since 2015, which is closely related to the importance of the country, the doctor-patient problems facing China today, and the people's livelihood issues. In terms of research results, from the perspective of theoretical research, some scholars put forward integration theory, synergistic effect, stakeholders, Pareto efficiency, game theory, halo effect and so on to explain and improve the system, but there is still a lack of deeper research and innovation in the management concept. From the perspective of the practice research of scholars around the study paths, supply and demand both sides will, recognition of investigation and study, from lack of practice deepening the research on to more specific aspects of the system, and clarifying the hierarchical system and basic medical insurance system, the basic drug system, relevant relations between system problems such as reform of public hospitals. The concept of hierarchical diagnosis and treatment has been advocated since the early days of the founding of the People's Republic of China. It has been nearly 70 years since then. How to find a new innovation path from the system level through closer communication and cooperation is a problem worth studying.

Hierarchical diagnosis and treatment, Research hotspots, Research evolution, Bibliometrics