The selected 41 articles were published between 2002 and 2017. The greatest number of papers were published in 2015 (n = 6); no articles were published in 2007. Thirty-3 articles were included in Chinese core journal criterion of Institute of Scientific and Technical Information of China (ISTIC), and 6 articles were included both in Chinese core journal criterion of Peking University (PKU) and ISTIC. Eight articles were not included in any of the core journals; no articles were Included in Science Citation Index (SCI).
3.1 Publishing journals of the articles
The 41 articles were published in 22 journals (Table 2), predominantly in Chinese general medical journals. The largest number of articles were published in the China Journal of Emergency Resuscitation and Disaster Medicine (n = 8), followed by the Chinese Journal of Aerospace Medicine (n = 6) and the Chinese Journal of Critical Care Medicine (n = 4). The China Journal of Emergency Resuscitation and Disaster Medicine and Chinese Journal of Aerospace Medicine were included in ISTIC, and Chinese Journal of Critical Care Medicine was included in both ISTIC and PKU.
3.2 Authorship, origins, and institutions
The majority (60.9%) of 41 articles were produced by teams involving >3 authors. A list of the most frequently appearing authors is presented in Table 3. It was clearly dominated by Xiangrui Xu, who authored 6 articles (first and corresponding author: 5; other author: 1) and Yingzhou Ding, who authored 3 articles (corresponding author: 3).
The 41 articles all originated in China but from 7 different regions (Fig. 2). The highest number (n = 14), came from East China, which has 400 million inhabitants; followed by North China (n = 12), which has 168 million inhabitants; Central China (n = 8) which has 223 million inhabitants; Southwest China (n = 3), which has 199 million inhabitants; South China (n = 2), which has 169 million habitants and Northwest China (n = 2), which has 100 million inhabitants. All other regions had no publications, as shown in Figure 2. Of the total 41 articles, the leading institution with the greatest number of articles was the Emergency Centre of Qingdao City (Qingdao, Shandong province; n = 7). The second was the Emergency Centre of Wuhan City (Wuhan, Hubei province; n = 4). The third was People's Liberation Army 252 Hospital (Baoding city, Hebei province; n = 3).
3.3 Publication type, funding source, and level of evidence
The 41 articles included 18 clinical studies, 12 reviews, and 11 clinical guidelines. Among the 41 articles, 22 were from public hospitals, 18 were from military units and 1 came from a private hospital. One article (4.5%) from the public hospitals was funded by public foundation, 11 articles from the army units (61.1%) received support from Army funding, and the article from a private hospital had no funding (see Table 4). Compared with the public and private hospitals, articles from military units were more likely to receive financial support (χ2 = 15.7, P <.01). The disclosed funding supported by the Army was 91.6% of all funds; that supported by public foundations constituted only 8.3%.
All the articles were assigned a level of evidence from 1 to 5. Level 5 (78.0%) was the most frequent level of evidence; there were 7 studies at level 4. Only 2 articles were assigned to level 3. There were no articles at levels 1 or 2.
The number of times the article was cited.
The most cited in all articles was Discussion on Helicopter Emergency Transport Process (n = 11). The next was Actuality and development of helicopter emergency medical service (n = 10). The third was Retrospect and Prospect of Helicopter Emergency Medical Rescue and Improve the city first aid function by Helicopters to transport critically ill patients (n = 8).
This study is the first to identify, rank and characterize the articles in the field of China's HEMS. The results of the research show the current status and characteristics of China's development in this area and provide information necessary for scholars in related fields to further promote the development of HEMS in China.
Bibliometric analysis is a tool that can quantify the characteristics and scholarly impact of citations in a given area of study. Understanding the characteristics of highly cited studies in relevant journals may help authors who wish to submit and publish effectively.
All articles examined came from China and were written in Chinese. This suggests that foreign experts and scholars may not have the means to understand the status of China's HEMS. This is one of the primary goals of this study: to enable foreign scholars to understand China's HEMS programme and thereby further assist in its development. Articles originated mainly from the eastern, northern, and central regions of China. In considering the reasons for this, it is worth pointing out: HEMS needs a higher capital investment compared with the ground vehicle first aid programme.[16–19] Thus the development of HEMS has a higher demand in terms of local economic strength. East China is at the forefront of China's reform and economic opening; its economic development is the most robust. North China contains the capital of China, Beijing, where a large number of scientific publications and colleges are located. Central China has a large population. This region contributes a great deal to the overall economy.
With regard to the institutions that served as the source of the articles, the top 3 were the Emergency Centre of Qingdao City, the Emergency Centre of Wuhan City and People's Liberation Army 252 Hospital. Qingdao is a coastal open city located in the east of China; it is also the home base of the Yellow Sea Fleet of the Chinese People's Liberation Army. The sailing project competition of the 2008 Beijing Olympic Games was held in Qingdao. Because of its geographical location and special military factors, its HEMS programme was carried out earlier and bore the characteristics of military and civilian combination. Wuhan city, in central China, was the first city to carry out HEMS in China; there were more reports about its HEMS than that of other provinces. People's Liberation Army 252 Hospital is a military unit with a large number of advantages over the public hospitals. In China, a great amount of helicopter resources have been deployed in the army, particularly the Army Air Force (often deployed in large cities). Military hospitals can carry out HEMS successfully with this support. Hongli Hospital is a private hospital which is worth our special attention. It is the only private hospital found that carries out HEMS. This shows that HEMS has been generally recognized as a viable programme—not only at national public hospitals but also at private hospitals.
We found that China's HEMS started late compared to Western developed countries. The earliest HEMS literature reports from Western countries can be traced back to the 1940s. In China, the first article about HEMS appeared in 2002. The total number of articles was also small; it was less than 50 after development of nearly 15 years. It also led to fewer citations of these articles. The most one was only 11 times to be cited. Some articles had not even been cited. There was a huge difference in the number of published articles per year. Our study further found that the appearance and development of HEMS in China closely tracked large national events. As an example, Beijing's successful bid for the Olympic Games was in July 2001, the Shanghai World Expo was held in 2010 and the 22nd APEC meeting was held in 2014. After these important years, the number of articles about HEMS increased significantly. The first report of HEMS in Shanghai was in 2011. It reported that Medical Emergency Centre of Qingpu District in Shanghai successfully completed several helicopter medical emergency missions during the Expo.
We found that there has been no cross-regional clinical study thus far that analyzed all 41 articles. Most of the cooperation regarding the articles still remain in the provincial units. In Hubei province, Wuhan city (as the center) carried out cooperation with the surrounding cities in that region. However, there has been a lack of unified norms and systems for HEMS in the country as a whole.
Regarding funds, public hospitals are very different from military hospitals. We can find that military units have paid more attention to HEMS research; further, HEMS in local public and private hospitals need to be further strengthened.
As a Chinese article, if it was included in both PKU and ISTIC, this indicates that the quality of the article was relatively high. Thirty-three articles were included in the ISTIC; the article quality, based on our assessment, was medium. All the articles were written in Chinese, so no articles were included in the SCI. In general, the quality of the articles about HEMS is not high. With regard to classification of the articles, most involved clinical research, review or clinical guidelines. Clinical research articles were mainly reported in the form of case reports, controlled and cohort studies. Review was descriptive and lacked meta-research. Clinical guidelines were mainly based on personal advice and guidance. There was a lack of uniform guideline with respect to treatment.
In general, the level of evidence of the articles was low. Studies about HEMS in China were lacking both in quality and evidence level. This may be related to the relatively recent start of China's HEMS and lack of a large number of cases. We believe that the quality and evidence level of the articles will improve with the further development of HEMS in China.
A total of 8 articles referred to the costs of HEMS. For example, the cost of HEMS in Wuhan City Emergency Centre was 1000 US dollars per hour. In Qingdao City Emergency Centre the cost was 1500 US dollars each time. In general, the cost of HEMS was high. In recent years, Beijing has introduced commercial insurance. The patient has the right to reimburse the cost of HEMS after paying an annual insurance fee. The annual insurance fee is 50 to 150 US dollars per year.
China's HEMS has only recently started. Compared with Europe and the United States, its level of development is low, interregional development is uneven, and cooperation is insufficient. We need to strengthen capital investment and develop a unified guideline to further enhance the development of HEMS in China.
DX searched the scientific literature and drafted the manuscript. PL contributed to conception, design and data interpretation. SL helped to collect the data and performed statistical analyses. FH, H-C P and RP contributed to conception, design, data interpretation, manuscript revision for critical intellectual content and supervision of the study. All authors read and approved the manuscript.
Data curation: Ding Xu.
Formal analysis: Sheng Li.
Methodology: Peng Luo.
Project administration: Roman Pfeifer.
Software: Peng Luo.
Supervision: Frank Hildebrand, Hans-Christoph Pape.
Writing – original draft: Ding Xu.
Writing – review & editing: Ding Xu.
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Keywords:Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
bibliometric analysis; China; helicopter; HEMS; rescue; transport