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A bibliometric analysis of exertional heat stroke research in Web of Science

Contributed equally
Military Medical Research20163:31

https://doi.org/10.1186/s40779-016-0101-6

Received: 24 March 2016

Accepted: 10 October 2016

Published: 20 October 2016

Abstract

Background

Exertional heat stroke is a fatal condition and remains a health problem. This paper evaluates the publication trend regarding exertional heat stroke research between 1996 and 2015 using a bibliometric method.

Method

Articles regarding exertional heat stroke research published between 1996 and December 2015 were searched for in the SCI-EXPANDED database of Web of Science. The search results were analyzed with regard to publication year; publication quantity regarding countries/regions, and authors; citation frequency; and journal distribution. CiteSpace (v3.6) was used for a document co-citation visualization analysis.

Results

In total, 289 publications on heat stroke were located. After selection, 209 original articles conducted across 28 countries/regions and published in 83 journals were included in the analysis. The USA, Isreal, and France were the most common locations for exertional heat stroke studies. The CiteSpace visualization cluster analysis showed that exertional heat stroke-related mortality and protective measures were constant concerns of research.

Conclusions

Research related to exertional heat stroke has been continuous concerned. USA is still the leading country in this field.

Keywords

Heat strokeBibliometric analysis

Background

Heat stroke is a severe and fatal condition clinically characterized by a severe rise in core body temperature (often >40 °C), with concomitant central nervous system dysfunctions such as delirium, convulsions, epilepsy, and coma [1]. Heat stroke is primarily classified into classic heat stroke and exertional heat stroke. The latter is particularly encountered during modern warfare and military training. Over the past few decades, the incidence of exertional heat stroke has significantly increased. According to data from the US Centers for Disease Control and Prevention, 7,000 cases of heat stroke death occurred in the US between 1979 and 1997 [2]. Along with the change in global climate, the progress of urbanization, and the extension of life expectancy, exertional heat stroke is expected to remain a health problem that cannot be ignored [3]. The most common treatment for exertional heat stroke is rapid cooling to promptly lower body temperature to normal. This strategy can reduce the risk of organ damage [4]. Despite effective cooling, numerous patients suffer from multiple organ failure, disability, and even death following active cooling treatment. Several studies related to exertional heat stroke have been published over the last few decades [13]. However, many problems remain to be addressed regarding the pathogenesis, prevention, and treatment of exertional heat stroke [3]. Bibliometric analysis is a wildly used method to evaluate the publication trend on a special topic [5].

Although many papers investigated exertional heat stroke, reports are still currently lacking regarding the trend of exertional heat stroke publications. We aimed to employ a bibliometric method to analyze the trend of exertional heat stroke publication in the latest twenty years.

Methods

This trend analysis was performed using the Web of Science database with regard to publication quantity, country/region, institution, author, journal, and so on. The co-citation patterns were visualized to provide evidence for relevant clinics and research.

Data source and retrieval

The SCI-EXPANDED database of Web of Science was searched, and the last search occurred on June 14, 2016. The search terms “heat stroke” or “heatstroke” and “exertional” were used to create the following search queries: (topic = “heat stroke”) OR (topic = heatstroke)) AND “exertional”. The time span was set to between 1996 and 2015. The publication type was not limited, and “article” was selected for an in-depth analysis.

Statistical analyses

Histcite 12.03.07 (Thomson Reuters) was used for the descriptive analysis. A bibliometric method was used to quantitatively describe the published articles regarding year of publication; publication quantity, including country/region, institution, and author; citation frequency; and journal distribution. A citation map was generated. The co-citation visualization analysis was performed using CiteSpace 3.6.

Results

Selection of articles

Using the search queries, 289 publications were searched, including 209 original articles, 37 reviews, 11 editorials, 10 meeting abstracts, 10 letters, 8 proceedings papers, 4 corrections. Based on the selection criteria, 80 non-original articles were excluded, and 209 original articles related to exertional heat stroke were included in the analysis.

Distribution of articles by publication years

The quantity of published articles on exertional heat stroke showed an overall trend by year, which rose from 12 in 1996 to 31 in 2015 (Table 1).
Table 1

Number and citation frequency of published articles on extertional heat stroke between 1996 and 2016

Publication year

Articles

Citation frequency

Average citation frequency

1996

12

485

40.4

1997

4

38

9.5

1998

6

105

17.5

1999

3

135

45.0

2000

1

24

24.0

2001

6

82

13.7

2002

6

93

15.5

2003

10

98

9.8

2004

11

318

28.9

2005

7

213

30.4

2006

12

244

20.3

2007

12

250

20.8

2008

7

117

16.7

2009

10

192

19.2

2010

11

151

13.7

2011

16

120

7.5

2012

9

111

12.3

2013

12

61

5.1

2014

23

43

1.9

2015

31

43

1.4

Total

209

2923

14.0

Distribution of articles by countries and regions

The 209 articles originated from 28 countries and regions. The USA, Isreal, France, Mainland China and Taiwan, and UK were the most common locations for publishing articles on exertional heat stroke (Table 2). USA is the leading country during the twenty years in publishing articles on exertional heat stroke.
Table 2

An analysis of the number and citation frequency of published articles with regard to major countries/regions

Rank

Country/region

Total records

Publication year

Total citation

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

1

USA

105

8

0

3

0

1

3

4

4

3

3

7

6

2

4

7

10

3

5

10

22

1725

2

Israel

19

0

0

0

1

0

0

1

2

6

0

2

0

0

0

0

4

1

1

1

0

266

3

France

14

1

1

0

1

0

1

0

0

0

1

1

0

1

1

2

0

0

0

2

2

177

4

Mainland China

13

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

2

1

1

4

4

37

5

UK

12

1

0

0

0

0

0

0

0

0

1

0

2

1

0

0

0

1

2

0

4

283

6

Taiwan

11

1

2

0

0

0

0

0

1

2

0

0

0

0

0

2

1

1

0

1

0

109

Distribution of articles by authors

The 209 articles were written by 803 authors in total. The top 10 authors publishing articles on exertional heat stroke primarily came from the US and Israel (Table 3). Casa DJ from the University Connecticut of USA published the most articles (20 records) and accounted for 9.6 % of all published articles. Casa DJ published the first article on exertional heat stroke in 2005 [6]; the most recent research on exertional heat stroke was published in 2015 [7].
Table 3

Ten authors who published at least 10 articles on exertional heat stroke from 1996 to 2016

Rank

Author

Records

Citations

Average citation

Country/region

Institution

1

Casa DJ

20

302

15.1

USA

University Connecticut

2

Armstrong LE

12

325

27.1

USA

University Connecticut

3

Epstein Y

9

253

28.1

Israel

Tel Aviv University

4

Moran DS

9

203

22.6

Israel

Tel Aviv University

5

Roberts WO

8

241

30.1

USA

University of Minnesota

6

Wenger CB

8

255

31.9

USA

US Army Research Institute of Environmental Medicine

7

Heled Y

7

131

18.7

Israel

Heller Institute of Medical Research

8

Maresh CM

7

193

27.6

USA

University Connecticut

9

Gardner JW

6

191

31.8

USA

Uniformed Services University of the Health Sciences

10

McDermott BP

6

114

19.0

USA

University of Tennessee

Distribution of articles by journals

The 209 articles were published across 105 journals. The top 10 journals published 83 articles on heat stroke and accounted for 32.9 % of all articles included in this study (Table 4). The JOURNAL OF ATHLETIC TRAINING published the most articles (16). Ellis A published the most frequently cited article in Gut in 1996 which was referenced 102 times [8].
Table 4

Top ten SCI journals for heat stroke publications

Journals

Records

Categories

Quartile

F2014

Journal of athletic training

16

Sport sciences

Q2

2.017

Medicine and science in sports and exercise

16

Sport sciences

Q2

3.983

Military medicine

12

Medicine, general & internal

Q3

0.911

Aviation space and environmental medicine

8

Medicine, general & internal/public, environmental & occupational health/sport sciences

Q3/Q4/Q5

0.875

Journal of applied physiology

7

Physiology/sport sciences

Q2/Q1

3.056

Wilderness & environmental medicine

6

Public, environmental & occupational health/sport sciences

Q3/Q3

1.196

European journal of applied physiology

5

Physiology/sport sciences

Q3/Q2

2.187

Journal of thermal biology

5

Biology/zoology

Q2/Q2

1.505

American family physician

4

Primary health care/medicine, general & internal

Q1/Q2

2.175

Journal of strength and conditioning research

4

Public, environmental & occupational health/sport sciences

Q3/Q3

1.196

Citation map

One of the core documents cited was published by Epstein Y in 1999, titled “Exertional heat stroke: a case series” [9]. Another core document cited was published by Smith JE in 2005, titled “Cooling methods used in the treatment of exertional heat illness” [10] (Fig. 1).
Fig. 1

A citation map, with Ref 9 and Ref 10 as core documents

Analysis of time-frequency of key words

The time frequency of the keywords was obtained via a co-citation analysis using CiteSpace (Fig. 2). The core documents co-cited were subject to a cluster analysis (Table 5). Fifteen categories were generated in the cluster analysis, with the following nine major categories: “fulminant hepatic failure”, “contribution”, “near-fatal exertional heat stroke”, “plasma beta-endorphin concentration”, “marine corp”, “suspected heat illness”, “distance”, “air force”, and “energy metabolism” et al. In this figure, the timeline of clusters labeled using keywords is shown horizontally. The earliest concern was “marine corp”.
Fig. 2

Timeline for the keyword analysis of the document co-citation clustering

Table 5

Documents at the nodes of the co-citation clusters

Frequency (cited times)

Centrality (article’s degree of centralized in the cluster)

Year

Co-cited articles

84

0.30

2002

Bouchama A, 2002, New Engl J Med, V346, P1978, DOI 10.1056/NEJMRA011089

51

0.06

2007

Armstrong LE, 2007, Med Sci Sport Exer, V39, P556, DOI 10.1249/MSS.0B013E31802FA199

35

0.31

1990

Costrini A, 1990, Med Sci Sport Exer, V22, P15

30

0.06

2002

Binkley HM, 2002, J Athl Train, V37, P329

29

0.17

1990

Shapiro Y, 1990, Med Sci Sport Exer, V22, P6

28

0.09

1999

Epstein Y, 1999, Med Sci Sport Exer, V31, P224, DOI 10.1097/00005768-199902000-00004

27

0.10

2007

Casa DJ, 2007, Exerc Sport Sci Rev, V35, P141

24

0.07

2005

Casa DJ, 2005, Curr Sport Med Rep, V4, P309

23

0.04

2004

Rav-acha M, 2004, Am J Med Sci, V328, P84, DOI 10.1097/00000441-200408000-00003

22

0.28

1996

Armstrong LE, 1996, Am J Emerg Med, V14, P355, DOI 10.1016/S0735-6757(96)90048-0

22

0.17

1967

Shibolet S, 1967, Q J Med, V36, P525

22

0.11

2003

Proulx CI, 2003, J Appl Physiol, V94, P1317, DOI 10.1152/JAPPLPHYSIOL.00541.2002

22

0.09

1998

Dematte JE, 1998, Ann Intern Med, V129, P173

21

0.13

2005

Smith JE, 2005, Brit J Sport Med, V39, P503, DOI 10.1136/BJSM.2004.013466

84

0.30

2002

Bouchama A, 2002, New Engl J Med, V346, P1978, DOI 10.1056/NEJMRA011089

Discussion

According to classical bibliometric theory, increases or decreases in the number of scientific research publications indicate the speed of scientific/technological development. The present study shows that the number of published research articles on exertional heat stroke between 1996 and 2015. These publications indicate several findings. First, heat stroke research has been of continuous concern. Second, environmental heat damage, sports heat damage, and military action training heat damage remain problems that cannot be ignored. Finally, many problems have yet to be solved regarding the diagnosis, treatment, and prognosis of heat stroke.

With regard to distribution by country/region, US and Israel are the two leading countries. Mainland China published the most articles on heat stroke ranking No.4. Previous bibliometric studies in other fields have also found a sharp increase in the number of research articles from Mainland China, exceeding Hong Kong and Taiwan [1113] and ranking second only to the US [14]. The continuous research progress in the number of published articles on exertional heat stroke demonstrates the overall improvements in critical care medicine, sports medicine, and military medicine in the output country.

With respect to journal distribution, the top 10 journals publishing articles on exertional heat stroke were all specialist publications, and none were comprehensive. On one hand, this evidence indicates that exertional heat stroke research is relatively esoteric. Most of these top 10 journals were classified as quartile 2 or 3 SCI publications. These journals mainly focus on Sport Science or Military Medicine. Although impact factor has been extensively used to evaluate the quality of research published [15], its value has always been questioned. Professor Alberts, the editor-in-chief of Science, the top journal in the sciences, recently published an editorial stating that impact factor has led to abnormalities in the research evaluation system [16]. Moreover, high impact factor journals occasionally publish low-quality research. Therefore, we did not analyze or discuss impact factor in the present study.

Recently, an increasing number of bibliometric analyses have emerged in medicine [1113, 1720] and have demonstrated significant value [21]. Previous analyses have shown that the number of published articles grew rapidly in certain countries that are emerging in scientific research, which reduced the share of articles from traditional research powers in Europe and the US [22]. A 2010 study showed that 100 classic publications in Bone Science were primarily from the UK and the US [23]. The authors of that study predicted that China would reverse this situation and establish a new balance in the near future [21]. As the present study revealed, this trend has begun to show in heat stroke research. Furthermore, we performed a visualization cluster analysis of co-cited documents on heat stroke and listed core documents in these clusters.

The present study has a few limitations. For example, to perform the citation analysis, we only searched the SCI database and not the Medline or Embase databases. However, we are certain that the SCI database generally includes all mainstream documents in the natural sciences.

Conclusions

In summary, the research evidence gained continous attention in exertional heat stroke-related fields. USA is the dominated country in this field.

Abbreviation

SCI: 

Science Citation Index

Declarations

Funding

None.

Availability of data and materials

All data generated or analyzed during this study are included in this published article [and its supplementary information files].

Authors’ contributions

ZM and CL contributed equally to this work. ZM and CL conceived the study, participated in the design, collected the data, performed statistical analyses, and drafted the manuscript. SC performed statistical analyses, and helped to draft the manuscript. ZGZ and HJK revised the manuscript critically for important intellectual content. FHZ performed statistical analyses, helped to revise the manuscript critically for important intellectual content. All authors read and approved the final manuscript.

Competing interests

The authors declare that they have no competing interests.

Consent for publication

Not applicable.

Ethics approval and consent to participate

Not applicable.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Department of Critical Care Medicine, Chinese PLA General Hospital
(2)
Department of Medical Information, Chinese PLA General Hospital
(3)
Department of Orthopedics, Chinese PLA General Hospital

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Copyright

© The Author(s). 2016

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