A Comparative Study of International and Chinese Public Health Emergency Management from the Perspective of Mapping Knowledge Domains

Background: At the end of 2019, the outbreak of the coronavirus disease 2019 (COVID-19) had severely damaging people’s life. China’s public health emergency management system had played an essential role in the handling and response of it, which had been appreciated by the World Health Organization and some countries. Hence it is necessary to make an overall analysis of the development of China’s health emergency management system. It can provide a reference for scholars to understand the current situation and look for new research points. Methods: We collected 2247 international from the Web of Science database, 959 Chinese articles from China National Knowledge Infrastructure database. Bibliometric and mapping knowledge domains analysis methods were used in this study for temporal distribution analysis, cooperation network, co-word network analysis. Results: The rst international article in this eld was published in 1991, while Chinese in 2005. Research institutions mainly come from universities and health institutions. Developed countries and European countries published more articles, while east of China published more. There are 52 burst words for international articles from 1999–2018, while 18 burst words for Chinese articles from 2003–2018. International top-ranked articles by citation appeared in 2005, 2007, 2009, 2014, 2015, 2016, while Chinese appeared in 2003, 2004, 2009, 2011. Conclusions: There are differences in the regional or economic distribution of international and Chinese cooperation networks. International research often relates to hot issues, mainly focus on the emergency preparedness and monitoring for public health events, while China’s focus on the public health emergency and their disposal. International begins the research with terrorism and bioterrorism, followed by disaster planning and emergency preparedness, epidemics and infectious diseases. China takes severe acute respiratory syndrome as the research background and legal system construction as the research starting point, followed by mechanism, structure, system, and learning from abroad of public health emergency management.


Data Sources
Data were divided into two categories: International and Chinese data. According to relevant authoritative research [ 20 ], the database of bibliometric methods should contain complete documents. A considerable amount of literature showed that Web of Science (WoS) was the largest comprehensive academic information resource, covering peer-reviewed journals with high impact factors [ 21 -24]. According to this all, the international data used for our study were collected from the WoS Core Collection, including Science Citation Index Expanded (SCI-E), Science Citation Index Expanded (SSCI), and Arts & Humanities Citation Index (A&HCI) databases. Chinese data was downloaded from the China National Knowledge Infrastructure (CNKI), which had the largest Chinese journal full-text database, including the vast majority of Chinese journals relating to public health management. More importantly, it has become one of the critical basic data sources for bibliometrics research in China [ 25 ].

Data Retrieval
Data obtained by inappropriate literature information retrieval strategy could not accurately re ect the content of the research [ 26 ]. Emergency management was a common term in China that focused on the occurrence, development, evolution of emergencies, and nding effective ways of responding to the emergency [ 27 ]. However, it was not certi ed for international. After consulting the experts from the Chinese CDC who once worked for the World Health Organization (WHO), we learned that the management was re ned by preparedness, operation, response, and recovery for an international public health emergency. Also, this had been mentioned in articles [5,28 ]. Based on the above points, the international data retrieval strategies were set as: ((TS = public health) AND (TS= preparedness OR TS= operation OR TS= response OR TS= recovery) AND TS= (emergency )) AND LANGUAGE: (English) AND DOCUMENT TYPES: (Article) Indexes = SCI-EXPANDED, SSCI, A&HCI, Timespan = 1988-2018. When retrieving Chinese data, we choose "public health" and "emergency management" as the theme-word, Timespan = "1988-2018". We ran the search query of WoS and CNKI on February 19, 2019. A total of 2759 articles from 1991 to 2018 were retained from WoS, while 999 articles from 2003 to 2018 were retained from CNKI.
After discussing with the team members, we further selected the articles based on inclusion and exclusion criteria to ensure that all of the data were closely aligned to the study targets. The inclusion criteria are as follows: (1) Occurrence, development, and evolution of PHEM; (2) Prevention, preparedness, response, operation and recovery of PHEM system; (3) Planning, organization, leadership, coordination, and control of public health emergency; (4) Practice and method of PHEM. Exclusion criteria as follows: (1) Health care, medical record management, disease treatment; (2) Guidelines on the action, proceedings paper or book chapter, interviews, summaries of conferences, and patent abstracts. Finally, 2247 international articles and 959 Chinese articles were accepted for the analysis after data ltering and removing duplication. The international articles were downloaded by the "Plain Text" format with a full record and cited references to classi cation and statistical analysis. The Chinese articles were downloaded by the "Refworks" format. Those download data contain the list of authors, the title of the publication, the abstract, keywords, and so on. With this, we had obtained the data for this study. Figure 1 shows the speci c search steps.

Data Analysis Tools
We used CiteSpace 5.5.R2 and Microsoft Excel 2016 for the data analysis. CiteSpace was a free Javabased application found by Chaomei Chen to analyze the potential knowledge contained in the scienti c literature. It had been widely adopted for scientometric analysis in various scienti c elds [ 29 ], and have achieved excellent results [ 30 , 31 ]. The parameters of CiteSpace for this study were set as follows: time slicing (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018), respectively), years per slice (1), term source (all selection), node type (Author, institution, keyword, for Chinese and international data. Country for international data.), selection criteria (top 50), and visualization (cluster view-static, show merged network). The corresponding other settings were selected according to different study questions. Microsoft Excel 2016 was used for temporal distribution and polynomial prediction of the number of articles. It should be noted that the results of the CNKI database made by CiteSpace were presented in Chinese. In order to make it easier to read, we translated the Chinese result into English.

Data Analysis Strategies
This study involved using bibliometric and mapping knowledge domains analysis method. Bibliometric methods provided an approach to identify the development trends or future research orientations by the combining of different tools and methods to analyze the articles [ 32 , 33 ]. It allowed researchers to generate information from historical data and indicators, such as keywords, authors, institutes, countries [ 34 ]. We were mainly engaged in cooperation network analysis (including the network analysis of the authors, institutions, and countries), co-word network analysis (including keyword co-occurrence network and burst detection analysis) in the mapping knowledge domains analysis. First, we made a statistical analysis of the temporal distribution of relevant articles. Then, we made a polynomial prediction of the number of articles, tted the trend line of international and Chinese study, and predicted it in the next three years. Cooperation network analysis was used to analyze the contribution to different authors, institutions, countries in one eld. It was obvious that the more an author, a country, or an institution publish its research ndings, the more contributions it will make [ 35 ]. Betweenness centrality is an index to measure the importance of nodes in the network. The purple circle represented documents with betweenness centrality not less than 0.1, which meant the authors, institutions, or countries occupied an essential position in this eld [20,36 ]. Co-word analysis was a content analysis technique that was effective against mapping co-occurrence relationships and the strength of the relationship between a pair of items existing in the same text, revealing the inner construction of a research eld [24]. Analysis of keywords co-occurrence network was meaningful and valuable in exploring the hot topics in a speci c knowledge domain [ 37 , 38 ]. Besides, keywords burst detection analysis can clearly grasp the articles that receive particular attention to the related scienti c communities in a certain period. Therefore, the frontiers founded by the burst detection analysis can provide researchers with up-to-date information [ 39 , 40 ]. The analysis of the highly cited articles in the eld can re ect the development of the discipline in a period, study hot topics, and supplement the above results, to provide a reference for scienti c researchers topic selection [ 41 ]. After the descriptive analysis of the data, we conducted a polynomial prediction analysis of the number of articles and predicted it in the next three years. The trend of chronological distribution of articles related to PHEM in international data can be expressed as follows: y = 0.2790x 2 +0.7688x-7.7708 (R 2 = 0.9577), while Chinese data was: y= -0.0345x 3 +1.5079x 2 -14.142x+27.273 (R 2 = 0.9251). Y indicated the number of articles and x indicated the years. R 2 > 0.9, indicating a good degree of t. The chronological distribution of international articles showed a trend of the increasing year by year. In 2019-2021, the annual number of articles will exceed that of previous years. At the same time, the trend line of Chinese articles like a wave line, and the number of articles will continue to decrease to the next three years.

Temporal Distribution Analysis
Besides, as time goes on, the gap in the number of articles in Chinese and international will be gradually increasing.

Cooperation Network Analysis
Co-Author Figure 3, the international co-author network, showed that there were many authors studied on PHEM, and some had collaborated. The top-ranked item by citation counts was Daniel J. Barnett (DANIEL J BARNETT in the gure) with a citation count of 20 (all the count did not show in the gure). Then was Elena Savoia (ELENA SAVOIA) and Lainie Rutkow (LAINIE RUTKOW); all their citation counts were 17. These were authors who paid great attention to this eld and had published more articles. Most of these authors were from American universities, such as Johns Hopkins University, Harvard University. The topranked items by centrality were Frederick M. Brokle (FREDERICK M), Task Force for Pediatric Emergency Mass Critical Care (TASK FORCE PEDIAT EMERGENCY MASS C CA) and James G. Hodge (JAMES G), with the centrality of 0.06 (all the centrality did not show in the gure). However, all three items' centrality was less than 0.1. Figure 4, the top-ranked item for Chinese scholars by citation counts was Qunhong Wu with citation counts of 22. Then was Yanhua Hao (17), Feng Han (11), Ning Ning (10), Yadong Wang (10), Zheng Kang (8), Ying Liu (6), Jincheng Ma (6), Mingli Jiao (5), Libo Liang (5). Most of them were teachers at Harbin Medical University. The top-ranked items by centrality were Yanhua Hao, and Ning Ning, with the centrality of 0.02. The third one was Qunhong Wu, with the centrality of 0.01. Their nodes' centrality also less than 0.1. In terms of the quantity and quality of articles, Qunhong Wu and Yanhua Hao were the leaders of PHEM in China. From the co-author network, we can see that many authors in internationally and China are collaborating on PHEM. (Additional le 1: Table S1, Table S2, and Figure   S1).

Co-Institution
Just like a co-author, many institutions had studied on PHEM ( gure 5 and gure 6). The top-ranked item by international citation counts was the Centers for Disease Control and Prevention (Ctr Dis Control & Prevent.), with citation counts of 255, which means that the institution publishes the largest number of articles in this eld. The second one was Johns Hopkins University (Johns Hopkins Univ.), with citation counts of 92, and it meant that Johns Hopkins University had the largest number of articles published among the universities in this eld. Then was Harvard University (Harvard Univ.), Columbia University (Columbia Univ.), and so on. The above analysis showed that CDC and universities were the leading institutions to study on international PHEM. The centrality ranked item was CDC (0.50). Then was Johns Hopkins University (0.21), Harvard University (0.16), University of Washington (Univ Washington., 0.13), University of Toronto (Univ Toronto., 0.10), University of Pittsburgh (Univ Pittsburgh, 0.10) and Boston University (Boston Univ., 0.10). All these nodes' centrality was no less than 0.1 with the purple circle, which meant that they were the institutions with higher publication quality and the leading institutions in this eld. The top-ranked item by citation counts of the Chinese database was the School of Health Management, Harbin Medical University, with citation counts of 20. Then was Shanghai Publishing and Printing College (9) Table S3, Table S4, and Figure S2). Table 1 summarized the top 10 countries in the count and centrality of international PHEM research. We can see that the development of PHEM researches differs from countries, and it mainly centralized in the USA, Canada, England, Australia, P. R. China, Switzerland, Italy, Sweden, Japan, Netherlands. According to the income levels from the World Bank [ 42 ], these countries were all high-income countries except China. Geographically, half of them centralized in Europe. Among these countries, the USA was the most productive country, far ahead of the rest in this eld, and its centrality was the largest. This showed that in the eld of PHEM, the USA carries out the most study, and their study was more advanced. Although

Co-Country
China ranks fth in the number, its centrality was only 0.03. Therefore, these results indicated that Chinese scholars could publish some internationally recognized articles in the eld, which had an advantage in quantity; but, they need to improve the articles' quality. It was worth noting that although the number of Switzerland (44) and Sweden (34) articles was much lower than that of the USA, the articles' centrality of these two countries was more than 0.10, which showed that the quality of the articles was still high. Generally speaking, keywords represent the research hotspots, which means topics of wide concern for researchers in this eld. From gure 7 we can saw, top 10 keywords ranked by citation counts for the international database was public health (297), preparedness (215), emergency preparedness (191), disaster (187), health (142), emergency (133), care (128), United States (121), bioterrorism (102), and impact (96). The top ten centrality was emergency department (0.22), prevalence (0.18), surveillance (0.17), knowledge (0.15), public health preparedness (0.15), children (0.14), management (0.14), trauma (0.13), simulation (0.13), policy (0.11). All their centrality was more than 0.10, which meant they had more in uence than other keywords. Figure 8 showed top 10 keywords of Chinese PHEM research was public health emergencies (394), emergency management (154), health emergency (116), public health (101), emergencies (84), emergency response ability (78), public health events (58), emergency mechanism (33), emergency disposal (28), public emergencies (27). Nodes whose centrality over 0.1 was health emergency (0.45), public health (0.32), public health emergencies (0.30), emergency management (0.26), emergencies (0.23), public health events (0.13), and emergency response ability (0.12). Comparing the distribution of keywords in the international and Chinese, we can see that the international study mainly focuses on the emergency preparedness and monitoring for public health events, while the Chinese research mainly focuses on the analysis and disposal for it. (Additional le 1: Table S5, Table S6, and Figure S3).
Burst Detection Analysis Figure 9 and gure 10 illustrated the keywords with the strongest citation burst for international and Chinese databases.  Figure S4).
In order to further explain the above research hotspots, the top 8 cited articles were shown in

Discussion
International research on PHEM is earlier than the Chinese one, and it has been growing over time. This means that international scholars pay more and more attention to PHEM. In 1991, the rst article on PHEM was written by Richard L. Siegel, named Code 9: a systematic approach for responding to medical emergencies occurring in and around a hospital [ 56 ]. It mentioned the need for an organized system to respond to such emergencies involving patients, visitors, local community residents, and hospital employees, both inside the hospital and on the grounds surrounding the building. They recommend the establishment of a systematic emergency response system in all health care institutions. Since then, academia has begun to pay attention to emergency management of public health incidents. The number of international articles is increasing gradually, reaching the maximum in 2017, and it is expected to continue to grow in the next three years. The development of PHEM in China shows a uctuating pattern.
The occurrence of public health emergencies in the ten years, from 2006 to 2016, showed a general trend of rising rst and then slowly declining. It is likely related to the number of signi cant events that occur in each year [ 57 ]. The severe acute respiratory syndrome (SARS) epidemic in 2003 resulted in signi cant increases in both the amount of research and articles on emergency management [7]. The number of articles reached a small climax in 2008. Events such as the Wenchuan earthquake, the southern snow disaster happened in that year. The maximum was in 2013, human infection with H7N9, Ya'an earthquake, death from hepatitis B vaccine happened in that year. Moreover, it was ten years after the SARS outbreak; some authors compared the development of PHEM in China for ten years. The rst Chinese article on PHEM was written by Tiewu Jia, named Capacity-building for public health emergency response to disasters (2003) [ 58 ]. This article was published during the epidemic of SARS. In 2003, China did not established a network and echelon PHEM system. The author combined the development of emergency management, reform of health and epidemic prevention institutions, discussed the capacity building of public health emergency response. It is helpful for the social function orientation of the disease control center and the improvement of the disease prevention ability. Although the number of Chinese articles decreased in the following years, it remained above 48. In a word, the above analysis shows that PHEM is still a hot topic.
From the perspective of cooperative networks, we nd that there is more cooperation among Chinese authors, yet less cooperation among the authors from different institutions. The cooperation between different research institutions is believed to be highly effective in facilitating high-level and fruitful research, which can also help develop the research eld into a more established area [ 59 ]. Therefore, Chinese scholars should strengthen cooperation between different institutions. The research institutions on PHEM mainly come from universities and health institutions, while Chinese has regional differences. Reasons include that the western region had the poor scal capacity, a limited personnel size, and an inadequate stockpile in terms of working budget, timely reserves, and prompt delivery [ 60 ]. As a leader in international PHEM, CDC had begun to help other entities strengthen their capacity, recognition, and technical expertise to strengthen their PHEM capacity [ 61 ]. Also, some other health institutions, such as the WHO, had promoted the development in this eld. In 2005, the 58 th World Health Assembly (WHA) adopted the revised International Health Regulations, which instructed the WHO member states to collaboratively confront public health emergencies of global attention [5,17,62 ]. Universities have undertaken the scienti c task of PHEM, and they have conducted in-depth research on it in China.
Chinese CDC has carried out more disease prevention and control services; its scienti c research ability is slightly weak. The country network analysis shows obvious differences in regional and economic development levels for PHEM. Those countries with more developed health emergency management systems are the most high-income ones. Geographically, most of these countries are concentrated in Europe, where numbers of publications and citations are also signi cantly higher [60]. The United States, the United Kingdom, Japan, and other countries have built and improved their PHEM constantly, which has become a comprehensive management network.
The co-word analysis on the international research of PHEM is more complex, extensive, and multidimensional. They re ect some of the major ideas of this research. Based on them, scholars mainly focus on emergency preparedness and monitoring for public health events. From the perspective of Chinese PHEM development, it has gone through a process from theory to preparation, disposal, response, evaluation, organization, and discussion. That is to say, the main contents of China's health emergency management include the prevention and preparation of health emergencies, as well as the key links of disposal, evaluation and management, system construction, personnel training, and so on. In a word, the development of the whole discipline is systematic and clear. Embriaco focused on the working condition of emergency management personnel [46]. Kim Knowlton [44] and Salim S. Abdool Karim [47], mentioned the emergency department. The above three articles are all about the factors involved in health emergency management. The remaining articles analyze the speci c events involving the mechanism, response, and recovery [43,[48][49][50]. From the above analysis, it can be seen that terrorism, emergency response and health incident management, disposal of public health events are the hotspots of international attention. Legislative situation and characteristics of China's emergency law [53], Legal construction of public emergency response in China: legal construction task proposed by SARS crisis management practice [54], and The realistic subject of administrative rule of law in public emergency management [55] were published in 2003. All three articles discussed the problems existing in the construction of the administrative legal system under the background of SARS.
After that, three articles were published in 2004, mainly studied the mechanism and structure of PHEM in China. It was proposed to establish the emergency response mechanism for PHEM and establish emergency structure construction as soon as possible. In 2009, Kaibin Zhong wrote the article Review and prospect: construction of emergency management system in China [52]. He elaborated on the core contents of Chinese PHEM construction, including emergency plan, emergency structure, emergency mechanism, and legal system. China's PHEM integrates emergency systems, emergency mechanisms and legal systems in an all-round way, which is characterized by comprehensiveness, institutionalization, openness, and guarantee. In 2011, The status quo of emergency management system for sudden public health events in America and Japan and its enlightenment [ 64 ] was published, showed us China is learning the theory and experience of PHEM in some advanced countries. From the above analysis, it can be seen that the legal system, mechanism and structure, system, and learning from abroad are the theoretical guidance for the Chinese PHEM in the past 30 years.
Admittedly, there are some limitations. Firstly, conclusions drawn from this study were based on only two large literature retrieval libraries. Other databases such as Embase, Springer Link were not studied. Not being able to search all the literature in this eld may lead to the retrieval results incomplete. Secondly, CiteSpace has some shortcomings in processing the results of the Chinese database; it cannot translate the result from Chinese into English directly. Thirdly, one year or more time lag is between our papersubmitted and published. The database articles may change during this time. Fourthly, although we conducted a comparison between Chinese and international databases, like many similar studies. It should be acknowledged that the two databases had different acceptance ratio, and this difference in data sources might lead to bias in the study results. Besides, we categorized those English articles focus on China into an international database, did not analyze them alone. Although only a small part of it, that may have some de ciencies. This may constitute the object of future studies, namely analyze the differences between English papers focusing on China vs. Chinese papers.

Conclusions
In summary, we selected two large documents of retrieval library to de ne the PHEM domain, detected the research status and trends of it from 1991 to 2018. According to the analyses, conclusions are as follows. In the next three years, the number of international PHEM articles will continue to increase, while the Chinese will decline. Chinese scholars have less cooperation among different organizations. There are differences in regional or economic distribution between international and Chinese cooperation networks. China focuses on the east regionally, while developed countries and European countries are more international. International research often relates to hot issues, mainly focus on the emergency preparedness and monitoring for public health events, while China's focuses on the public health emergency and their disposal. The research of PHEM in international begins with terrorism and bioterrorism, followed by disaster planning and emergency preparedness and emerging infectious diseases. China takes SARS as the research background and legal system construction as the research starting point, followed by mechanism and structure, system, and learning from abroad.