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A Bibliometric Analysis of the Articles Focusing on the Subject of Brain Death Published in Scientific Citation Index-Expanded Indexed Journals: Analysis of 3487 Articles Published Between 1995-2019
A Bibliometric Analysis of the Articles Focusing on the Subject of Brain Death Published in Scientific Citation Index-Expanded Indexed Journals: Analysis of 3487 Articles Published Between 1995-2019 S. Yılmaz Ferhatoglu* and N. Yapici Department of Anesthesiology and Reanimation, University of Health Sciences Dr. Siyami Ersek Training and Research Hospital, Istanbul, Turkey
ABSTRACT Background. Although the topic of brain death (BD) has been increasing in popularity considerably in recent years by the snowballing number of patients suffering from endorgan failure and waiting for organ transplantation, the literature indicates insufficient information regarding the comparison of scientific articles focusing on BD, authors’ and nations’, even governments’ tendency about this issue. Objectives. In the present study, we aimed to make a bibliometric analysis of the articles focusing on the subject of BD, which is one of the most trendy topics in organ transplantation. Material and Methods. The terms "brain death," were searched in Thomson Reuters, Web of Science search engine for the years between 1995 and 2019. All the articles found were subjected to bibliometric analysis. Results. Web of Science database included 3487 articles. The United States was found to be the most productive country in all methods, and Transplantation Proceedings was the journal that contributed most to the literature on the subject of BD. A positive correlation between publication productivity and gross domestic product/gross domestic product per capita and human development index was found (r ¼ 0.470, P < .05; r ¼ 0.359, P < .05; r ¼ 0.603, P < .001, respectively). Also, there was a negative correlation between the number of published articles and the population of the country (r ¼ e0.083, P < .001). Conclusion. Although the top country focusing on the subject of BD was the United States in terms of bibliometrics, we found that there is a correlation between the indices measuring the welfare and development level of the country and publication productivity about BD, which means developed countries show more tendency about BD, which is the main component of the definitive treatment of end-organ failure.
T
HE definition of the diagnosis of brain death (BD) is the constant end of all functions of the whole brain, including the brainstem and physiopathologically intracranial blood circulation [1-3]. With the improvement of organ transplantation procedures, and the increment in the number of people suffering from end-organ failure, organ transplantation from a cadaveric donor has become momentous; therefore, determining BD has become a vital issue [4,5]. Holistic evaluation of scientific publications is the definition of "bibliometrics” [6,7]. Evaluation of scientific ª 2020 Elsevier Inc. All rights reserved. 230 Park Avenue, New York, NY 10169
Transplantation Proceedings, XX, 1e6 (2020)
citations is a bibliometric analysis based on citation collaborations among authors, publications, organizations, or countries/nations [8]. The Internet allows a quick way to online access to scientific publications or databases; hence,
*Address correspondence to Sibel Yılmaz Ferhatoglu, MD, Department of Anesthesiology and Reanimation, University of Health Sciences Dr. Siyami Ersek Training and Research Hospital, Istanbul, Turkey. Tel: þ905052600701. E-mail: sibelyf@ yandex.com 0041-1345/20 https://doi.org/10.1016/j.transproceed.2020.01.034
1
2
FERHATOGLU AND YAPICI
MATERIALS AND METHODS General Information We used for obtaining the datum of this research the search engine of Thomson Reuters, Web of Science Website (http://apps. webofknowledge.com). We performed a search by selecting the Core Collection as the database, which is the leading database collecting citation, and other academic impact information globally [10] by using the keyword “brain death” by selecting the “Topic” section on October 1, 2019 (Fig 1). We sorted the articles in order of date, which is the current Web of Science default.
Inclusion Criteria The publications published between 1995 and 2019 were included to study protocol. Fig 1. Search engine of Web of Science Website.
Exclusion Criteria
there has been an increment in the number of scientific publications in online indexes/databases such as PubMed and Web of Science [9]. In line with the snowballing development of the online world, the meaning of bibliometric research rises as it enables a holistic evaluation of the scientific publications. This kind of study shows the topmost dynamic authors, publications, active journals, and collaborations between the countries, and these studies become a guide for the researchers [8]. Although identification of BD is of relevance for profiting from organ/tissue transplantation of patients suffering from end-organ failure, the literature still does not include bibliometric researches that conducted a holistic analysis of the publications about BD subject. Based on the presented study, we aim to analyze the topcited articles about BD published between the years 1995 and 2019 according to the database of Web of Science, Core Collection to asses the citation collaboration of the articles, show the partnership among the countries and journals, and report the newest improvements and trend topics about this subject.
We refined the search results in order to document type as “Article.” The other publication types were excluded from the study protocol.
Evaluation of the Collected Data We used the analysis function of the Website for assessment. The publication rates, according to years, countries, and languages, were examined. Citation and h-index data were evaluated.
Ethical Approval All procedures performed in studies involving human participants were following the Helsinki declaration and its later amendments or comparable ethical standards.
Statistical Analysis We used the Number Cruncher Statistical System 2007 (Kaysville, Uta, United States) computer application for statistical assessment of the data. We applied descriptive statistical techniques (mean, standard deviation, median, first quadrant, third quadrant, frequency, percentage, minimum, maximum) for the evaluation of data. Spearman correlation analysis was applied to assess the associations among quantitative variables. The estimate of correlation was considered as 0.26 < r < 0.49 low correlation; 0.50 < r < 0.69
Fig 2. Publications and citations metrics according to years.
BIBLIOMETRIC ANALYSIS OF BRAIN DEATH ARTICLES
3
Table 1. Publication and Citation Metrics According to Countries Article n (%)
Citation n (%), Mean SD (min-max)
United States 1179 (33.81) 11,376 (36.9), 189.45 261.62 (0-4520) Germany 247 (7.08) 2900 (9.43), 65.31 122.65 (0-1240) England 235 (6.73) 2484 (8.07), 100.17 135.1 (0-1322) Spain 196 (5.62) 1453 (4.72), 45.25 45.86 (0-451) Canada 175 (5.01) 1838 (5.97), 100.48 90.3 (0-694) Japan 175 (5.01) 1325 (4.3), 45.52 50.26 (0-41)7 Italy 154 (4.41) 1511 (4.91), 75.86 86.77 (0-609) France 153 (4.38) 1515(4.92), 100.15 124.74 (0-855) Netherlands 151 (4.33) 1230 (4), 135.92 124.74 (0-413) PRC 126 (3.61) 1673 (5.44), 20.44 22.64 (0-211)
Table 2. According to Web of Science Categories, the Most Cited Journals About "Brain Death” Topic
h-index
Web of Science Categories
Records
% of 4719
35
Surgery Transplantation Critical Care Medicine Clinical Neurology Immunology Cardiac Cardiovascular Systems Neurosciences Medicine General Internal Respiratory System Anesthesiology Gastroenterology Hepatology Pediatrics Emergency Medicine Peripheral Vascular Disease Medicine Research Experimental Urology Nephrology Pharmacology Pharmacy Radiology/Nuclear Medicine Engineering Biomedical Biochemistry Molecular Biology Social Sciences Biomedical Ethics Multidisciplinary Sciences Cell Biology Medical Ethics
7.615 5.409 3.927 3.793 2.651 2.609 2.132 1.891 1.745 1.339 1.318 1.264 1.096 1.093 970 827 808 709 633 614 607 602 509 486 460
23.99 17.04 12.37 11.95 8.35 8.22 6.71 5.95 5.49 4.22 4.15 3.98 3.45 3.44 3.05 2.6 2.54 2.23 1.99 1.93 1.91 1.89 1.6 1.53 1.45
15 9 17 15 9 10 16 19 6
Abbreviations: PRC, People’s Republic of China; SD, standard deviation.
moderate correlation; 0.70 < r < 0.89 high correlation; 0.90 < r < 1.00 very high correlation. Statistical significance was accepted as P < .05.
RESULTS Development of Publications
Since 1995, 4521 publications have been published on BD. The distribution of the publications according to document type are as follows: article 3840 (85.9%); proceedings paper 584 (12.9%); book chapter 83 (1.83%); early access article, etc 13 (0.28%); and data paper 1 (0.02%). We conducted the bibliometric analysis in the present study with 3840 publications, which were articles. Language
The distribution of the articles according to language are as follows: English 3487 (90.8%); German 132 (3.43%); Spanish 86 (2.23%); French 70 (1.82%); Russian 12 (0.31%); Japanese 11 (0.28%); Portuguese 11 (0.28%); Turkish 9 (0.23%); Italian 5 (0.13%); Czech 4 (0.1%); Croatian 3 (0.07%); Polish 3 (0.07%); Chinese 2 (0.05%); Korean 2 (0.05%); Greek 1 (0.02%); Hungarian 1 (0.02%); and Swedish 1 (0.02%). We continued assessment only including articles in English. Development of Citations
The h-index of the 3487 articles in English was 97. The publication and citation metrics according to years and countries are shown in Fig 2. The 5 most productive countries in 5-year periods are as follows: 1995-2000, United States, France, Japan, Spain, Germany; 2000-2005, United States, Germany, Spain, Japan, Canada; 2005-2010, United States, France, Spain, Canada, Netherlands; 2010-2015,
United States, Germany, Spain, Netherlands, Canada; and 2015-October 2019, United States, Spain, Germany, People Republic of Chine, Italy (Table 1). In the analysis of the citation numbers since 1995, it was seen that the articles were cited a total of 31,728 times (including self-citations). An increase in the citation numbers according to years are shown in Fig 2. Citation numbers by country are shown in Table 1. According to the Web of Science categories, journals about surgery and transplantation are the most cited journals about the "brain death” topic (26.73% and 23.12%, respectively) (Table 2). Most Active Journals
Seven of the top 10 journals that focus on the BD issue are journals focusing on transplantation (Table 3), and the other 3 are journals focusing on critical care. Table 3. Top 10 Journals Focusing on Brain Death Journal Name
n
%
Transplantation Proceedings Transplantation Critical Care Medicine American Journal Of Transplantation Resuscitation Liver Transplantation Intensive Care Medicine Transplant International Journal of Heart and Lung Transplantation Clinical Transplantation
1.058 900 688 628 525 418 360 327 312 293
3.334 2.836 2.168 1.979 1.655 1.317 1.135 1.031 0.983 0.923
4
FERHATOGLU AND YAPICI Table 4. The Authors Produced the Highest Number of Publications About “Brain Death” Author
Publication Rate, n (%)
Wijdicks EFM
25 (3.8)
Ploeg RJ
18 (2.73)
Ramirez P
16 (2.43)
Rios A
16 (2.43)
Parrilla P
15 (2.28)
Greer DM
13 (1.97)
DominguezRoldan JM Leuvenink HGD Lewis A
12 (1.82)
Pratschke J
10 (1.52)
12 (1.82) 11 (1.67)
Nation
Institution
United Mayo Clinic States Netherlands University of Oxford Spain University of Murcia Spain University of Murcia Spain University of Murcia United University of States Boston Spain University of Seville Netherlands University of Groningen United University of States New York Germany University of Berlin
Expertise
Neurology Surgery Surgery Surgery Surgery Neurology Neurology Surgery Neurology Surgery
Most Active Authors
The authors who produced the highest number of publications about “brain death” are shown in Table 4. Most Active Organizations
The most active organizations about the BD topic are Harvard University, Mayo Clinic, and VA Boston Healthcare System, which are health providers from the United States (Table 5). Analysis of Correlation Between Publication Statistics and Global Domestic Product/Human Development Index/ Population
There was a positive correlation between publication numbers and global domestic product (GDP), GDP per capita (GDPpp), and human development index (HDI) (r ¼ 0.470, P < .05; r ¼ 0.359, P < .05; r ¼ 603, P < .001, respectively) (Fig 3). Also, there was a negative correlation between the number of published articles and the population of the country (r ¼ e0.083, P < .001) (Table 6). DISCUSSION
Our study proves the increase in the publication productivity over the last 25 years. This progression highlights the value of bibliometric analysis, which facilitates researchers in further studies. The number of scientific articles concerning BD has shown a significant increment in the last decade [11], especially in the United States. Spain, Germany, and France are the other developed countries following the United States in the publication productivity about BD.
Table 5. Most Active Organizations Focusing on Brain Death Organization
Record Count n (%)
Nation
Harvard University Mayo Clinic VA Boston Healthcare System University of Groningen University of California System Brigham Women’s Hospital Ruprecht Karls University Heidelberg Assistance Publique Hopitaux Paris APHP New York University Free University of Berlin Institut National De La Sante Et De La Recherche Medicale Inserm University of Cape Town Duke University Humboldt University of Berlin Massachusetts General Hospital Virgen Del Rocio University Hospital Charite Medical University of Berlin Hospital Clinico Universitario Virgen De La Arrixaca Universidade De Sao Paulo Loma Linda University Pennsylvania Commonwealth System of Higher Education Universite Catholique Louvain University of California Los Angeles University of Murcia Chu Lyon
54 (1.5) 44 (1.26) 35 (1)
United States United States United States
29 (0.83) 27 (0.77)
Netherlands United States
26 (0.74) 25 (0.71)
United States Germany
23 (0.65)
France
23 (0.65) 22 (0.63) 22 (0.63)
United States Germany France
19 (0.54) 18 (0.51) 18 (0.51)
South Africa United States Germany
18 (0.51)
United States
18 (0.51)
Spain
16 (0.45)
Germany
16 (0.45)
Spain
16 (0.45) 15 (0.43) 15 (0.43)
Brazil United States United States
15 (0.43)
Belgium
15 (0.43)
United States
15 (0.43) 14 (0.4)
Spain China
Nevertheless, the enrichment of the undeveloped/developing nations such as the People's Republic of China and Turkey was notable. Turkey plus the People Republic of China have outstanding efficiency in scientific publications about BD. In 2007, the Chinese Ministry of Health declared the Regulation on Human Organ Transplantation to describe primary steps to control the organ transplantation and donation system, which caused an increase in organ donation numbers [12]. Similar to China, the increasing publication productivity of Turkey, which is a developing country, could be associated with the number of physicians in the BD commission reduced from 4 to 2 in 2014. This development in BD commission eased and fastened BD diagnosis, which created an increase in the number of BD diagnosed patients [11]. It is obvious that diagnosing is the initial step of composing a scientific
BIBLIOMETRIC ANALYSIS OF BRAIN DEATH ARTICLES
5
Fig 3. Correlation between article numbers and gross domestic product/population.
paper. We think the expanding number of scientific articles centering on BD directly correlated with the number of patients diagnosed with BD in Turkey and China. Similar to Turkey and China, Iran emerged a novel model in 1988, which has been based on providing financial support to living donors. The new model lowered the organ waiting list and showed a rise in the number of transplantation procedures, harmonious with this model, publication productivity of Iran has improved [13,14]. The Iran, Turkey, and the People's Republic of China examples show undeveloped and developing nations may formulate new regulations to facilitate and to speed up the Table 6. Publication Numbers and Gross Domestic Product/ Human Development Index Relation
Nation
United States Germany England Spain Canada Japan Italy France Netherlands China
Article (n)
GDP in Trillions ($)
GDPpp ($)
1179
21.41
65,064
329,064,917
0.924
247 235 196 175 175 154 153 151 126
4.42 3.02 1.58 1.91 5.36 2.26 3.06 0.99 15.54
52,885 44,759 33,889 51,015 42,269 37,349 46,984 58,184 10,841
83,517,045 67,530,172 46,736,776 37,411,047 126,860,301 60,550,075 65,129,728 17,097,130 1,433,783,686
0.936 0.922 0.891 0.926 0.909 0.880 0.901 0.931 0.752
Population (n)
HDI
GDP data were obtained from the website of International Monetary Fund. HDI data were obtained from the website of United Nations Development Programme, Human Development Report 2017. Abbreviations: GDP, gross domestic product; GDPpp, gross domestic product per capita; HDI, human development index.
process of the diagnosis of BD by adhering to scientific principles. The rate of willingness for being an organ donor ranges within 29.7% and 75% in Middle East nations [11,15]. However, the desire for organ donation ranges between 51.8% and 90% in European society [15-18]. The willingness for organ donation in Pakistan was found as 3.5% [19]; Beutel et al found this ratio as 20% in Germany [20]. The publication rates about BD or BD-related issues in the countries in the Arabian Peninsula and Africa was nearly none. It is reflected that there is a connection between writing potency about BD and the willingness to be an organ donor. Wijdicks EFM from the United States and Ploeg RJ from the Netherlands have the highest publication productivity about the topic of BD. The study of Wijdicks et al “Evidence-based guideline update: Determining brain death in adults Report of the Quality Standards Subcommittee of the American Academy of Neurology” published in the Journal of Neurology in 2010 had the highest citation numbers per year. Wijdicks et al evaluated 367 publications written between the years 1996 and 2009 and had suggestions on the diagnosis of BD [21]. The topic of BD is often considered as the subject of neurologists and intensive care (critical care) physicians. Although the subject is explained in detail in the main textbooks of neurology and intensive care, even cardiology, it is not included in surgical books in detail or summarized in a very short way. Interestingly, in the present study, 7 of the 10 most active authors about the topic BD were surgeons. We believe that this paradigm is exceptionally understandable because BD is the principal component of transplantation. GDP is one of the most common parameters used to pursue the form of a nation's economy. It involves various determinants, such as consumption and investment. It portrays the cumulative dollar worth of incomes and outcomes produced over a particular period. Many researchers investigated the relationship between GDP and health care systems [22-24]. Anbarci et al investigated the effect of GDP on donation rates and revealed that GDP is the strongest predictor of organ donation [25]. Also, Dogan and Kayir showed there is a positive correlation between publication rates focusing on BD and GDP/GDPpp of the countries. They also demonstrated the correlation between HDI and publication about BD. Following the literature, we found a significant correlation between the publication rate of articles focusing on BD and GDP/GDPpp and HDI. Additionally, we showed the negative correlation between increasing population and publication rates about BD, which is a highly understandable situation. It is obvious that the socioeconomic level will decrease with the increasing population, the welfare level decreases, and the budget allocated by the governments for scientific programs and research will decrease. On the other hand, as the socioeconomic level increases, organ donation rates, and the number of organ transplantations would increase. We believe that this leads to an increase in the number of transplant-related articles like the BD topic.
6
Limitations of the Study
Our study is the first research about BD articles published in Scientific Citation Index-Expanded journals in English. The main limitation of our study is not including databases other than the Web of Science. However, the Web of Science database is the most reliable data source about scientific publications. Also, the assessment of articles only in English may be interpreted as an obstacle to this research. However, the analysis of articles in lesser known languages other than English could not be done correctly by the authors of this article. Therefore, articles other than English were excluded.
CONCLUSION
The present study proves the increase in the publication productivity over the last 25 years. This progression highlights the value of bibliometric analysis, which facilitates researchers in further studies. Developing/undeveloped nations especially should be inspired to the investigation and to publish scientific investigations about BD and subjects related to BD, like transplantation, organ donation, or critical care. Many people have been suffering from end-organ failure, which can be treated only by organ transplantation. Accordingly, the collaborations and multidisciplinary investigations concerning organ donation, thus, BD should be promoted in all nations. Furthermore, more prominent collaborations should be organized between countries by national governmental support instead of little or local clusters.
REFERENCES [1] Oczkowicz G, Caban A, Budzi nski G, Suska-Switek A, Doli nska B, Czech E, et al. Comparison of vascular endothelial growth factor concentration in porcine kidneys removed from living donors after cardiac and brain death. Transplant Proc 2018;50: 2240e4. [2] Nakamura MT, Rodio GE, Tchaicka C, Padilha EF, Jorge AC, Duarte PAD. Predictors of organ donation among patients with brain death in the intensive care unit. Transplant Proc 2018;50:1220e6. [3] Tatli O, Bekar O, Imamoglu M, Gonenc Cekic O, Aygun A, Eryigit U, et al. Cerebral oximetry as an auxiliary diagnostic tool in the diagnosis of brain death. Transplant Proc 2017;49:1702e7. [4] Dosemeci L, Yilmaz M, Cengiz M, Dora B, Ramazanoglu A. Brain death and donor management in the intensive care unit: experiences over the last 3 years. Transplant Proc 2004;36:20e1. [5] Karasu D, Yilmaz C, Karaduman I, Cinar YS, Pekel NB. Retrospective analysis of patients with brain death. J Med Surg Intens Care Med 2015;6:23e6. [6] Muslu Ü, Demir E. Development of rhinoplasty: yesterday and today. Med Sci 2019;23:294e301. [7] Demir E. The evolution of spirituality, religion and health publications: yesterday, today and tomorrow. J Relig Health 2018;58:1e13.
FERHATOGLU AND YAPICI [8] Ozsoy Z, Demir E. Which bariatric procedure is the most popular in the world? A bibliometric comparison. Obes Surg 2018;28:2339e52. [9] Aronsky D, Madani S, Carnevale RJ, Duda S, Feyder MT. The prevalence and inaccessibility of internet references in the biomedical literature at the time of publication. J Am Med Inform Assoc 2007;14:232e4. [10] Li L, Ma X, Pandey S, Deng X, Chen S, Cui D, et al. The most cited Works in severe traumatic brain injury: A bibliometric analysis of the 100 most cited articles. World Neurosurg 2018;113: 82e7. [11] Dogan G, Kayır S. Global scientific outputs of brain death publications and evaluation according to the religions of countries. J Relig Health 2020;59:96e112. [12] Huang J, Millis JM, Mao Y, Millis MA, Sang X, Zhong S. A pilot programme of organ donation after cardiac death in China. Lancet 2012;379:862e5. [13] Ghods A. Renal transplantation in Iran. Nephrol Dial Transplant 2002;27:222e8. [14] Beard TR, Kaserman DL, Osterkamp R. The global organ shortage. Economic causes, human consequences, policy responses. Stanford: Stanford University Press; 2013. [15] Mohsin N, Militsala E, Budriddin M, Al-Khawaldi H, Al-Dhuhli Y, Al-Rahbi Y, et al. Attitude of the Omani population toward organ transplantation. Transplant Proc 2010;42: 4305e8. [16] Conesa C, Rios A, Ramirez P, Conteras M, Rodriguez MM, Parrilla P. Attitudes toward organ donation in rural areas of South eastern Spain. Transplant Proc 2006;38:866e8. [17] Alashek WA, Ethuish EF, Elhabashi A, Emberish W, Mishra A. Reasons for unwillingness of Libyans to donate organs after death. Libyan J Med 2009;4:110e3. [18] Boghl L, Madsen M. Attitudes, knowledge and proficiency in relation to organ donation: a questionnaire based analyses in donor hospitals in Northern Denmark. Transplant Proc 2005;37:3256e7. [19] Saleem T, Ishaque S, Habib N, Hussain SS, Jawed A, Khan AA, et al. Knowledge, attitudes and practices survey on organ donation among a selected adult population of Pakistan. BMC Medical Ethics 2009;10:5. [20] Beutel ME, Greif-Higer G, Haselbacher A, Galle PR, Otto G. Einstellungen zur postmortalen Organspende - Ergebnisse einer Repräsentativerhebung der deutschen Bevölkerung [Attitudes towards cadaveric organ donation results from a presentative survey of the German population]. Zeitschrift für Gastroenterologie 2006;44:1135e40 [in German]. [21] Wijdicks EF, Varelas PN, Gronseth GS, Greer DM. Evidence-based guideline update: determining brain death in adultsd Report of the quality standards subcommittee of the American academy of neurology. Neurology 2010;74:1911e8. [22] Fuchs VR. Why do other rich nations spend so much less on healthcare? In: Health Economics and Policy Selected Writings by Victor Fuchs, chapter 23. Singapore: World Scientific Publishing Co Pte Ltd; 2018. p. 259e63. [23] Mladenovic I, Milovancevic M, Mladenovic SS, Marjanovic V, Petkovic B. Analyzing and management of health care expenditure and gross domestic product (GDP) growth rate by adaptive neuro-fuzzy technique. Comput Hum Behav 2016;64:524e30. [24] Reyes EB, Ha JW, Firdaus I, Ghazi AM, Phrommintikul A, Sim D, et al. Heart failure across Asia: same healthcare burden but differences in organization of care. Int J Cardiol 2016;223:163e7. [25] Anbarci N, Caglayan M. Cadaveric vs live-donor kidney transplants: the interactions of institutions and inequalities. Miami: Florida International University, Department of Economics; 2005.
ABSTRACT Background. Although the topic of brain death (BD) has been increasing in popularity considerably in recent years by the snowballing number of patients suffering from endorgan failure and waiting for organ transplantation, the literature indicates insufficient information regarding the comparison of scientific articles focusing on BD, authors’ and nations’, even governments’ tendency about this issue. Objectives. In the present study, we aimed to make a bibliometric analysis of the articles focusing on the subject of BD, which is one of the most trendy topics in organ transplantation. Material and Methods. The terms "brain death," were searched in Thomson Reuters, Web of Science search engine for the years between 1995 and 2019. All the articles found were subjected to bibliometric analysis. Results. Web of Science database included 3487 articles. The United States was found to be the most productive country in all methods, and Transplantation Proceedings was the journal that contributed most to the literature on the subject of BD. A positive correlation between publication productivity and gross domestic product/gross domestic product per capita and human development index was found (r ¼ 0.470, P < .05; r ¼ 0.359, P < .05; r ¼ 0.603, P < .001, respectively). Also, there was a negative correlation between the number of published articles and the population of the country (r ¼ e0.083, P < .001). Conclusion. Although the top country focusing on the subject of BD was the United States in terms of bibliometrics, we found that there is a correlation between the indices measuring the welfare and development level of the country and publication productivity about BD, which means developed countries show more tendency about BD, which is the main component of the definitive treatment of end-organ failure.
T
HE definition of the diagnosis of brain death (BD) is the constant end of all functions of the whole brain, including the brainstem and physiopathologically intracranial blood circulation [1-3]. With the improvement of organ transplantation procedures, and the increment in the number of people suffering from end-organ failure, organ transplantation from a cadaveric donor has become momentous; therefore, determining BD has become a vital issue [4,5]. Holistic evaluation of scientific publications is the definition of "bibliometrics” [6,7]. Evaluation of scientific ª 2020 Elsevier Inc. All rights reserved. 230 Park Avenue, New York, NY 10169
Transplantation Proceedings, XX, 1e6 (2020)
citations is a bibliometric analysis based on citation collaborations among authors, publications, organizations, or countries/nations [8]. The Internet allows a quick way to online access to scientific publications or databases; hence,
*Address correspondence to Sibel Yılmaz Ferhatoglu, MD, Department of Anesthesiology and Reanimation, University of Health Sciences Dr. Siyami Ersek Training and Research Hospital, Istanbul, Turkey. Tel: þ905052600701. E-mail: sibelyf@ yandex.com 0041-1345/20 https://doi.org/10.1016/j.transproceed.2020.01.034
1
2
FERHATOGLU AND YAPICI
MATERIALS AND METHODS General Information We used for obtaining the datum of this research the search engine of Thomson Reuters, Web of Science Website (http://apps. webofknowledge.com). We performed a search by selecting the Core Collection as the database, which is the leading database collecting citation, and other academic impact information globally [10] by using the keyword “brain death” by selecting the “Topic” section on October 1, 2019 (Fig 1). We sorted the articles in order of date, which is the current Web of Science default.
Inclusion Criteria The publications published between 1995 and 2019 were included to study protocol. Fig 1. Search engine of Web of Science Website.
Exclusion Criteria
there has been an increment in the number of scientific publications in online indexes/databases such as PubMed and Web of Science [9]. In line with the snowballing development of the online world, the meaning of bibliometric research rises as it enables a holistic evaluation of the scientific publications. This kind of study shows the topmost dynamic authors, publications, active journals, and collaborations between the countries, and these studies become a guide for the researchers [8]. Although identification of BD is of relevance for profiting from organ/tissue transplantation of patients suffering from end-organ failure, the literature still does not include bibliometric researches that conducted a holistic analysis of the publications about BD subject. Based on the presented study, we aim to analyze the topcited articles about BD published between the years 1995 and 2019 according to the database of Web of Science, Core Collection to asses the citation collaboration of the articles, show the partnership among the countries and journals, and report the newest improvements and trend topics about this subject.
We refined the search results in order to document type as “Article.” The other publication types were excluded from the study protocol.
Evaluation of the Collected Data We used the analysis function of the Website for assessment. The publication rates, according to years, countries, and languages, were examined. Citation and h-index data were evaluated.
Ethical Approval All procedures performed in studies involving human participants were following the Helsinki declaration and its later amendments or comparable ethical standards.
Statistical Analysis We used the Number Cruncher Statistical System 2007 (Kaysville, Uta, United States) computer application for statistical assessment of the data. We applied descriptive statistical techniques (mean, standard deviation, median, first quadrant, third quadrant, frequency, percentage, minimum, maximum) for the evaluation of data. Spearman correlation analysis was applied to assess the associations among quantitative variables. The estimate of correlation was considered as 0.26 < r < 0.49 low correlation; 0.50 < r < 0.69
Fig 2. Publications and citations metrics according to years.
BIBLIOMETRIC ANALYSIS OF BRAIN DEATH ARTICLES
3
Table 1. Publication and Citation Metrics According to Countries Article n (%)
Citation n (%), Mean SD (min-max)
United States 1179 (33.81) 11,376 (36.9), 189.45 261.62 (0-4520) Germany 247 (7.08) 2900 (9.43), 65.31 122.65 (0-1240) England 235 (6.73) 2484 (8.07), 100.17 135.1 (0-1322) Spain 196 (5.62) 1453 (4.72), 45.25 45.86 (0-451) Canada 175 (5.01) 1838 (5.97), 100.48 90.3 (0-694) Japan 175 (5.01) 1325 (4.3), 45.52 50.26 (0-41)7 Italy 154 (4.41) 1511 (4.91), 75.86 86.77 (0-609) France 153 (4.38) 1515(4.92), 100.15 124.74 (0-855) Netherlands 151 (4.33) 1230 (4), 135.92 124.74 (0-413) PRC 126 (3.61) 1673 (5.44), 20.44 22.64 (0-211)
Table 2. According to Web of Science Categories, the Most Cited Journals About "Brain Death” Topic
h-index
Web of Science Categories
Records
% of 4719
35
Surgery Transplantation Critical Care Medicine Clinical Neurology Immunology Cardiac Cardiovascular Systems Neurosciences Medicine General Internal Respiratory System Anesthesiology Gastroenterology Hepatology Pediatrics Emergency Medicine Peripheral Vascular Disease Medicine Research Experimental Urology Nephrology Pharmacology Pharmacy Radiology/Nuclear Medicine Engineering Biomedical Biochemistry Molecular Biology Social Sciences Biomedical Ethics Multidisciplinary Sciences Cell Biology Medical Ethics
7.615 5.409 3.927 3.793 2.651 2.609 2.132 1.891 1.745 1.339 1.318 1.264 1.096 1.093 970 827 808 709 633 614 607 602 509 486 460
23.99 17.04 12.37 11.95 8.35 8.22 6.71 5.95 5.49 4.22 4.15 3.98 3.45 3.44 3.05 2.6 2.54 2.23 1.99 1.93 1.91 1.89 1.6 1.53 1.45
15 9 17 15 9 10 16 19 6
Abbreviations: PRC, People’s Republic of China; SD, standard deviation.
moderate correlation; 0.70 < r < 0.89 high correlation; 0.90 < r < 1.00 very high correlation. Statistical significance was accepted as P < .05.
RESULTS Development of Publications
Since 1995, 4521 publications have been published on BD. The distribution of the publications according to document type are as follows: article 3840 (85.9%); proceedings paper 584 (12.9%); book chapter 83 (1.83%); early access article, etc 13 (0.28%); and data paper 1 (0.02%). We conducted the bibliometric analysis in the present study with 3840 publications, which were articles. Language
The distribution of the articles according to language are as follows: English 3487 (90.8%); German 132 (3.43%); Spanish 86 (2.23%); French 70 (1.82%); Russian 12 (0.31%); Japanese 11 (0.28%); Portuguese 11 (0.28%); Turkish 9 (0.23%); Italian 5 (0.13%); Czech 4 (0.1%); Croatian 3 (0.07%); Polish 3 (0.07%); Chinese 2 (0.05%); Korean 2 (0.05%); Greek 1 (0.02%); Hungarian 1 (0.02%); and Swedish 1 (0.02%). We continued assessment only including articles in English. Development of Citations
The h-index of the 3487 articles in English was 97. The publication and citation metrics according to years and countries are shown in Fig 2. The 5 most productive countries in 5-year periods are as follows: 1995-2000, United States, France, Japan, Spain, Germany; 2000-2005, United States, Germany, Spain, Japan, Canada; 2005-2010, United States, France, Spain, Canada, Netherlands; 2010-2015,
United States, Germany, Spain, Netherlands, Canada; and 2015-October 2019, United States, Spain, Germany, People Republic of Chine, Italy (Table 1). In the analysis of the citation numbers since 1995, it was seen that the articles were cited a total of 31,728 times (including self-citations). An increase in the citation numbers according to years are shown in Fig 2. Citation numbers by country are shown in Table 1. According to the Web of Science categories, journals about surgery and transplantation are the most cited journals about the "brain death” topic (26.73% and 23.12%, respectively) (Table 2). Most Active Journals
Seven of the top 10 journals that focus on the BD issue are journals focusing on transplantation (Table 3), and the other 3 are journals focusing on critical care. Table 3. Top 10 Journals Focusing on Brain Death Journal Name
n
%
Transplantation Proceedings Transplantation Critical Care Medicine American Journal Of Transplantation Resuscitation Liver Transplantation Intensive Care Medicine Transplant International Journal of Heart and Lung Transplantation Clinical Transplantation
1.058 900 688 628 525 418 360 327 312 293
3.334 2.836 2.168 1.979 1.655 1.317 1.135 1.031 0.983 0.923
4
FERHATOGLU AND YAPICI Table 4. The Authors Produced the Highest Number of Publications About “Brain Death” Author
Publication Rate, n (%)
Wijdicks EFM
25 (3.8)
Ploeg RJ
18 (2.73)
Ramirez P
16 (2.43)
Rios A
16 (2.43)
Parrilla P
15 (2.28)
Greer DM
13 (1.97)
DominguezRoldan JM Leuvenink HGD Lewis A
12 (1.82)
Pratschke J
10 (1.52)
12 (1.82) 11 (1.67)
Nation
Institution
United Mayo Clinic States Netherlands University of Oxford Spain University of Murcia Spain University of Murcia Spain University of Murcia United University of States Boston Spain University of Seville Netherlands University of Groningen United University of States New York Germany University of Berlin
Expertise
Neurology Surgery Surgery Surgery Surgery Neurology Neurology Surgery Neurology Surgery
Most Active Authors
The authors who produced the highest number of publications about “brain death” are shown in Table 4. Most Active Organizations
The most active organizations about the BD topic are Harvard University, Mayo Clinic, and VA Boston Healthcare System, which are health providers from the United States (Table 5). Analysis of Correlation Between Publication Statistics and Global Domestic Product/Human Development Index/ Population
There was a positive correlation between publication numbers and global domestic product (GDP), GDP per capita (GDPpp), and human development index (HDI) (r ¼ 0.470, P < .05; r ¼ 0.359, P < .05; r ¼ 603, P < .001, respectively) (Fig 3). Also, there was a negative correlation between the number of published articles and the population of the country (r ¼ e0.083, P < .001) (Table 6). DISCUSSION
Our study proves the increase in the publication productivity over the last 25 years. This progression highlights the value of bibliometric analysis, which facilitates researchers in further studies. The number of scientific articles concerning BD has shown a significant increment in the last decade [11], especially in the United States. Spain, Germany, and France are the other developed countries following the United States in the publication productivity about BD.
Table 5. Most Active Organizations Focusing on Brain Death Organization
Record Count n (%)
Nation
Harvard University Mayo Clinic VA Boston Healthcare System University of Groningen University of California System Brigham Women’s Hospital Ruprecht Karls University Heidelberg Assistance Publique Hopitaux Paris APHP New York University Free University of Berlin Institut National De La Sante Et De La Recherche Medicale Inserm University of Cape Town Duke University Humboldt University of Berlin Massachusetts General Hospital Virgen Del Rocio University Hospital Charite Medical University of Berlin Hospital Clinico Universitario Virgen De La Arrixaca Universidade De Sao Paulo Loma Linda University Pennsylvania Commonwealth System of Higher Education Universite Catholique Louvain University of California Los Angeles University of Murcia Chu Lyon
54 (1.5) 44 (1.26) 35 (1)
United States United States United States
29 (0.83) 27 (0.77)
Netherlands United States
26 (0.74) 25 (0.71)
United States Germany
23 (0.65)
France
23 (0.65) 22 (0.63) 22 (0.63)
United States Germany France
19 (0.54) 18 (0.51) 18 (0.51)
South Africa United States Germany
18 (0.51)
United States
18 (0.51)
Spain
16 (0.45)
Germany
16 (0.45)
Spain
16 (0.45) 15 (0.43) 15 (0.43)
Brazil United States United States
15 (0.43)
Belgium
15 (0.43)
United States
15 (0.43) 14 (0.4)
Spain China
Nevertheless, the enrichment of the undeveloped/developing nations such as the People's Republic of China and Turkey was notable. Turkey plus the People Republic of China have outstanding efficiency in scientific publications about BD. In 2007, the Chinese Ministry of Health declared the Regulation on Human Organ Transplantation to describe primary steps to control the organ transplantation and donation system, which caused an increase in organ donation numbers [12]. Similar to China, the increasing publication productivity of Turkey, which is a developing country, could be associated with the number of physicians in the BD commission reduced from 4 to 2 in 2014. This development in BD commission eased and fastened BD diagnosis, which created an increase in the number of BD diagnosed patients [11]. It is obvious that diagnosing is the initial step of composing a scientific
BIBLIOMETRIC ANALYSIS OF BRAIN DEATH ARTICLES
5
Fig 3. Correlation between article numbers and gross domestic product/population.
paper. We think the expanding number of scientific articles centering on BD directly correlated with the number of patients diagnosed with BD in Turkey and China. Similar to Turkey and China, Iran emerged a novel model in 1988, which has been based on providing financial support to living donors. The new model lowered the organ waiting list and showed a rise in the number of transplantation procedures, harmonious with this model, publication productivity of Iran has improved [13,14]. The Iran, Turkey, and the People's Republic of China examples show undeveloped and developing nations may formulate new regulations to facilitate and to speed up the Table 6. Publication Numbers and Gross Domestic Product/ Human Development Index Relation
Nation
United States Germany England Spain Canada Japan Italy France Netherlands China
Article (n)
GDP in Trillions ($)
GDPpp ($)
1179
21.41
65,064
329,064,917
0.924
247 235 196 175 175 154 153 151 126
4.42 3.02 1.58 1.91 5.36 2.26 3.06 0.99 15.54
52,885 44,759 33,889 51,015 42,269 37,349 46,984 58,184 10,841
83,517,045 67,530,172 46,736,776 37,411,047 126,860,301 60,550,075 65,129,728 17,097,130 1,433,783,686
0.936 0.922 0.891 0.926 0.909 0.880 0.901 0.931 0.752
Population (n)
HDI
GDP data were obtained from the website of International Monetary Fund. HDI data were obtained from the website of United Nations Development Programme, Human Development Report 2017. Abbreviations: GDP, gross domestic product; GDPpp, gross domestic product per capita; HDI, human development index.
process of the diagnosis of BD by adhering to scientific principles. The rate of willingness for being an organ donor ranges within 29.7% and 75% in Middle East nations [11,15]. However, the desire for organ donation ranges between 51.8% and 90% in European society [15-18]. The willingness for organ donation in Pakistan was found as 3.5% [19]; Beutel et al found this ratio as 20% in Germany [20]. The publication rates about BD or BD-related issues in the countries in the Arabian Peninsula and Africa was nearly none. It is reflected that there is a connection between writing potency about BD and the willingness to be an organ donor. Wijdicks EFM from the United States and Ploeg RJ from the Netherlands have the highest publication productivity about the topic of BD. The study of Wijdicks et al “Evidence-based guideline update: Determining brain death in adults Report of the Quality Standards Subcommittee of the American Academy of Neurology” published in the Journal of Neurology in 2010 had the highest citation numbers per year. Wijdicks et al evaluated 367 publications written between the years 1996 and 2009 and had suggestions on the diagnosis of BD [21]. The topic of BD is often considered as the subject of neurologists and intensive care (critical care) physicians. Although the subject is explained in detail in the main textbooks of neurology and intensive care, even cardiology, it is not included in surgical books in detail or summarized in a very short way. Interestingly, in the present study, 7 of the 10 most active authors about the topic BD were surgeons. We believe that this paradigm is exceptionally understandable because BD is the principal component of transplantation. GDP is one of the most common parameters used to pursue the form of a nation's economy. It involves various determinants, such as consumption and investment. It portrays the cumulative dollar worth of incomes and outcomes produced over a particular period. Many researchers investigated the relationship between GDP and health care systems [22-24]. Anbarci et al investigated the effect of GDP on donation rates and revealed that GDP is the strongest predictor of organ donation [25]. Also, Dogan and Kayir showed there is a positive correlation between publication rates focusing on BD and GDP/GDPpp of the countries. They also demonstrated the correlation between HDI and publication about BD. Following the literature, we found a significant correlation between the publication rate of articles focusing on BD and GDP/GDPpp and HDI. Additionally, we showed the negative correlation between increasing population and publication rates about BD, which is a highly understandable situation. It is obvious that the socioeconomic level will decrease with the increasing population, the welfare level decreases, and the budget allocated by the governments for scientific programs and research will decrease. On the other hand, as the socioeconomic level increases, organ donation rates, and the number of organ transplantations would increase. We believe that this leads to an increase in the number of transplant-related articles like the BD topic.
6
Limitations of the Study
Our study is the first research about BD articles published in Scientific Citation Index-Expanded journals in English. The main limitation of our study is not including databases other than the Web of Science. However, the Web of Science database is the most reliable data source about scientific publications. Also, the assessment of articles only in English may be interpreted as an obstacle to this research. However, the analysis of articles in lesser known languages other than English could not be done correctly by the authors of this article. Therefore, articles other than English were excluded.
CONCLUSION
The present study proves the increase in the publication productivity over the last 25 years. This progression highlights the value of bibliometric analysis, which facilitates researchers in further studies. Developing/undeveloped nations especially should be inspired to the investigation and to publish scientific investigations about BD and subjects related to BD, like transplantation, organ donation, or critical care. Many people have been suffering from end-organ failure, which can be treated only by organ transplantation. Accordingly, the collaborations and multidisciplinary investigations concerning organ donation, thus, BD should be promoted in all nations. Furthermore, more prominent collaborations should be organized between countries by national governmental support instead of little or local clusters.
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