Get Permission Santhakumar: Measuring the growth and trends of neurology research output during 2012-2021


Introduction

Neurology is a branch of medicine dealing with disorders of the nervous system. Neurology deals with the diagnosis and treatment of all categories of conditions and disease involving the central and peripheral nervous system including their coverings, blood vessels, and all effector tissue, such as muscle. Neurological practice relies heavily on the field of neuroscience, which is the scientific study of the nervous system. Neurology implies the branch of medicine pertaining to the study and treatment of disorders of the nervous system. The nervous system is a complex, sophisticated system that regulates and coordinates body activities. Neurology has been at the heart of the Chiropractic profession since its very beginning. But it is only in recent years that advances in clinical neuroscience have allowed us to understand how our treatments affect the nervous system; and how this effect can help us to restore and preserve good structure and function within the musculoskeletal system. 1

Scientometric analysis is the quantitative study of a subject growth by using bibliometric indicators and statistical tools and techniques. It throws light on the pattern of growth of individual to the respective subject literature, inter-relationship among different branches of knowledge, productivity, authorship pattern, degree of collaboration, pattern of collection building, and their use. Gradually the Scientometric studies are attaining the status of inter-disciplinary in nature. This is clear from the scientometric evidence from 2012 to 2021, the number of publications was increased from 1046 to 1204. There is a significant increase in the literature ttherefore the present study aims to know the growth and development of publications in the field of neurology.

Review of Literature

Review of literature plays a significant role of any research study.

Wang et al 2 carried out a visual analysis of global health research from the perspective of scientific output characteristics, scientific research cooperation networks, keywords, and highly cited literature based on the 14,692 document data retrieved from the Web of Science from 1996 to 2019. The results show that scholars’ interest in global health research is increasing, especially after the outbreak of SARS. The USA, England, Canada, Australia, and China have the most prominent contributions to global health research. Significant authors, high-impact journals, and core institutions were also identified. Chaman Sab 3 examined 29153 publications in medical research, the present study deals with the Assessment of Indian medicine research output as reflected in Web of Science (WOS) database for the period 2009 to 2018 for identifying the research output in the field of medical literature. It also provides a comparative evaluation and performance of different types of scientometric indicators, such as the number of publications, the number of citations, relative growth, doubling time, activity index, and collaboration from India.

Karthikeyan 4 examined the overall production of scientific articles in Neuroscience research during the period 1986-2015 in worldwide. The study finds that the total number of publications is between 100 and 1000 per year for the first fifteen years of study i.e. 1986-2000, more than 1000 but below 1500 during 2001 and 2004 and more than 3000 for the further study period 2005-2015. Gautam, Vinod Kumar 5 focused on the growth of neuroscience research in India and its impact on scholarly world. A total of 4812 data was collected from the Scopus database for the period of 2004-2018. Analysis of the data revealed a considerable increase in the Annual Growth Rate in neuroscience research with a 10.52% CAGR for the entire period. Relative Growth Rate (RGR) was increasing with minor fluctuations i.e. growth in Neuroscience research is not an exponential ratio rather than it is the arithmetic ratio and Doubling Time is similar to RGR. Author Shukla, D. is the most productive author contributing 42 articles.

Sivasami 6 discussed on Scientometric analysis of research on neurophysiology, the data have been accessed from the Scopus database. A total of 1366 records were retrieved from the Scopus database, the year-wise analysis shows neurophysiology research publications an increasing and decreasing trend. In the document type-wise research publications on neurophysiology, the article has the first position with 506 publications, among the top twenty authors, De Paola, L. has the first place with 1.61 percent contributions on neurophysiology research, collaborative contributions are more, single authors' contributions are very least. Alhibshi 7 analyzed the Neurosciences research productivity in the Kingdom of Saudi Arabia (KSA) from 2013-2018 based on the Scopus database. Saudi Arabia is ranked 39th in publishing neuroscientific research worldwide. The number of yearly published articles has increased from 123 to 332 during the time between 2013 and 2018. King Saud University & King Abdul Aziz University & their corresponding regions namely the Western and Central regions are the major contributors to publications. Neuroscientists working in Saudi Arabia collaborate with scientists from all over the world. The top 10 preferred journals are international. 8, 9, 10, 11, 12

Objectives for the Study

The present study has following objectives as enumerated bellow:

  1. Year wise growth of publications

  2. Most prolific authors

  3. Highly productive countries

  4. Most productive institutes

  5. Most preferred source titles and

  6. High productive subject areas

Materials and Methods

Web of Science bibliographic database was used to harvest the bibliographical details of referred research publications on neurology in topic field. The Web of Science database allows us to refine the results in terms of publication years, countries, institutes, authors, subjects and source titles. The Time Span was used from 2012 to 2021. Total 12,639 research publications were retrieved with this search syntax for research analysis.

Data Analysis and Interpretations

Form of publications

Table 1

Form of publications

S.No.

Title

Articles

Percentage

1

Articles

9364

74.09

2

Review articles

1607

12.71

3

Editorial materials

1210

9.57

4

Letters

298

2.36

5

Book reviews

49

0.39

6

Biographical-Items

43

0.34

7

Corrections

39

0.31

8

News Items

17

0.13

9

Reprints

7

0.05

10

Poetry

2

0.02

11

Retractions

2

0.02

12

Retracted publications

1

0.01

Total

12639

100.00

Neurology research has been published in different forms of publications in the world. Out of the 12639 published papers, 9364 (74.09%) were Journal articles followed by Review articles with 1607 (12.71%), Editorial materials with 1210 (9.57%), Letters with 298 (2.3.6%) and the remaining forms are less than 1% of the publications. This is interesting to note that, the study neurology research researchers have contributed more in the form of journal articles.

Relative growth rate (RGR)

The Relative Growth Rate (RGR) is the increase in number of articles or pages per unit of time. This definition derived from the definition of relative growth rates in the study of growth analysis in the neurology research. The mean relative growth rate (R) over the specific period of interval can be calculated from the following equation.

Relative growth rate (RGR)

1 - 2R=Log W2 – Log W1/ T2-T1

Whereas

1-2 R- mean relative growth rate over the specific period of interval

Loge W1 - log of initial number of articles

Loge W2 - log of final number of articles after a specific period of interval

T2-T1- the unit difference between the initial time and the final time

The year can be taken here as the unit of time. The RGR for articles is hereby calculated.

Therefore

1-2) can represent the mean relative growth rate per unit of articles per unit of year over a specific period of interval.

    1-2/ T-T

Doubling time (DT)

There exists a direct equivalence between the relative growth rate and the doubling time. If the number of articles or pages of a subject doubles during a given period then the difference between the logarithms of numbers at the beginning and end of this period must be logarithm of the number 2. If natural logarithm is used this difference has a value of 0.693. Thus, the corresponding doubling time for each specific period of interval and for both articles and pages can be calculated by the formula.

Doubling Time (DT) = 0.693/R

Therefore,

Doubling time for articles Dt (a)= 0.693/1-2)

Table 2

Relative growth rate (RGR) and Doubling time (DT) of publications

Year

No. of Publications

Percentage

W1

W2

RGR

DT

2012

1442

11.41

-

7.27

-

-

2013

1177

9.31

7.27

7.07

-0.20

-3.46

2014

1069

8.46

7.07

6.97

-0.10

-6.93

2015

1132

8.96

6.97

7.03

0.06

11.55

2016

1184

9.37

7.03

7.08

0.05

13.86

2017

1046

8.28

7.08

6.95

-0.07

-9.90

2018

1204

9.53

6.95

7.09

0.14

4.95

2019

1193

9.44

7.09

7.08

-0.01

-6.93

2020

1451

11.48

7.08

7.28

0.20

3.46

2021

1741

13.77

7.28

7.46

0.18

3.85

A total of 12639 publications were published during 2012-2021. The average number of publications per year was 1263.9. The highest publications (1741) were in 2021 and the lowest publications (1046) was 2017. It was observed that there was a fluctuation trend of publications during 2012-2021.

The year wise relative growth rate is found to be in the range of -0.01 to 0.20. It has been observed from Table 2 and figure 2 that RGR is fluctuation trend from 2013 (-0.20) to 2020 (0.20). The doubling time was also fluctuation trend from 2013 (-3.46) to 2016 (13.86).

Identification of most prolific authors

Table 3

Identification of most prolific authors

S.No.

Author

No. of publications

Percentage

1

Anonymous

155

1.23 %

2

Matsumoto N

63

0.50 %

3

Okumura A

59

0.47 %

4

Saito Y

47

0.37 %

5

Sasaki M

46

0.36 %

6

Yamamoto T

43

0.34 %

7

Saitsu H

42

0.33 %

8

Takahashi Y

37

0.29 %

8

Sugai K

36

0.28 %

10

Gronseth G S

34

0.28 %

11

Maegaki Y

33

0.26 %

12

Osaka H

32

0.25 %

13

Haginoya K

31

0.24 %

14

Kobayashi K

31

0.24 %

15

Saito T

31

0.24 %

16

Nakagawa E

30

0.24 %

17

Yamagata T

30

0.24 %

A total number of 4,489 authors were identified from the 12,639 published bibliographic research articles. The authors having 30 or more publications during the study period are given in Table 3. Anonymous is the most productive author with 155 (1.23%) publications followed by Matsumoto N with 63 (0.50%) publications, Okumura, A with 59 (0.47%) publications, Saito Y with 39 (0.37%) publications, Sasaki M with 46 (0.36%) publications, Yamamoto T with 43 (0.34%) publications, and Saitsu H with 42 (0.33%) publications. Total of 51,689 authors are contributed entire research output of the study period.

Author’s productivity

In a study of author productivity, a large number of authors were classified according to the number of articles they had published during a certain period. To calculate Author productivity a formula has been applied. The formula is mathematically represented as below:

Average Author per Paper = No. of Authors/No. of Papers

Productivity per Author = No. of Papers/No. of Authors

Table 4

Author productivity

Year

No of Authors

No of Articles

Average Author Per Paper

Productivity per Author

2012

6351

1442

4.40

0.23

2013

4392

1177

3.73

0.27

2014

3194

1069

2.99

0.33

2015

3963

1132

3.50

0.28

2016

4105

1184

3.47

0.29

2017

3648

1046

3.49

0.29

2018

4686

1204

3.89

0.26

2019

5236

1193

4.39

0.23

2020

7548

1451

5.20

0.19

2021

8746

1741

5.02

0.20

It is one of the productivity of the total authors involved in contributing the research productivity. But the contribution of individual authors can’t measured in these methods of measurements. Table 4 depicts the data pertaining to author productivity and average author per paper. It is revealed from the table no. 4 that the average number of authors per articles is 4.01 for 12639 articles published between the periods 2012 to 2021.

The average productivity per author for the period 2012 to 2021 is 0.26. It is also clear from above table that for the years 2012, 2019 and for the years 2016, 2017 years are equal average productivity per author is recorded i.e., 0.23 and 0.29 respectively.

Degree of Collaboration

The degree of collaboration is defined as the ratio of the number of collaborative research articles to the total number of research articles in the subject during a certain period of time. The formula suggested by Subramanyam (1983) is used. It is expressed as

Nm

C = ---------------

    Nm + Ns

Where, C is the degree of collaboration in a discipline. Nm is the number of multiauthored research papers in the discipline published during a year. Ns is the number of single authored papers in the discipline published during the same year.

Table 5

Degree of collaboration

Year

Single Author

Multi Authors

Total

Degree of Collaboration

No. of Output

Percentage

No. of Output

Percentage

2012

176

9.17

1266

11.81

1442

0.88

2013

231

12.03

946

8.82

1177

0.80

2014

143

7.45

926

8.64

1069

0.87

2015

197

10.26

935

8.72

1132

0.82

2016

167

8.70

1017

9.49

1184

0.86

2017

89

4.63

957

8.93

1046

0.91

2018

159

8.28

1045

9.75

1204

0.87

2019

281

14.63

912

8.51

1193

0.76

2020

218

11.35

1233

11.50

1451

0.85

2021

259

13.49

1482

13.82

1741

0.85

Total

1920

100.00

10719

100.00

12639

8.47

The authorship pattern was analysed to determine the percentage of single and multiple authors. Table 5 presents the single and multiple authors productivity pattern on yearly basis. There were 10719 (84.81%) multi authored and only 1920 (15.19%) single authored publications. The productivity patterns on the neurology publications are much contributed by the multiple authors than the single author since 2012 to 2021.

The degree of collaboration is determined by using this formula based on this study, the degree of collaboration C = 0.85. i.e, 85 percents of collaborative author's articles is published in this study. The degree of collaboration in producing research output on neurology research has shown a fluctuating trend.

Highly productive countries

Table 6

Highly productive countries

S. No.

Country

Total Publications (%)

S.No.

Country

Total Publications (%)

1

USA

4232 (33.48%)

10

Australia

485 (3.84%)

2

England

1345 (10.64%)

11

Turkey

387 (3.06%)

3

Germany

1088 (8.61%)

12

Spain

358 (2.83%)

4

Japan

1080 (8.54%)

13

Switzerland

343 (2.71%)

5

Italy

956 (7.56%)

14

Austria

284 (2.25%)

6

Canada

788 (6.23%)

15

India

251 (1.99%)

7

France

677 (5.36%)

16

South Korea

231 (1.83%)

8

China

652 (5.16%)

17

Belgium

230 (1.82%)

9

Netherlands

528 (4.18%)

18

Sweden

221 (1.75%)

H gives highly productivity countries ((≥200 publications) in Neurology research. In all there were146 countries that have at least one publication in the research field of Neurology. USA topped the list with highest share 4232 (33.48%) of publications. England ranked second with 1345 (10.64%) share of publications followed by Germany 1088 (8.61%) share of publications, Japan with 1080 (8.54%) share of publications, Italy with 956 (7.56%) share of publications, Canada with 788 (6.23%) share of publications, France with 677 (5.36%) share of publications, China with 652 (5.16%) share of publications, Netherlands with 528 (4.18%) share of publications and Australia with 485 (3.84%) share of publications respectively.

Highly productive institutes

Table 7

Highly productive institutes

S.No.

Institutions

Country

No. of Publications

1

Mayo Clinic

USA

331 (2.62%)

2

Harvard Medical School

USA

255 (2.02%)

3

UCL Institute of Neurology

UK

222 (1.76%)

4

Massachusetts General Hospital

USA

206 (1.63%)

5

University of California San Francisco

USA

205 (1.62%)

6

University of Toronto

Canada

195 (1.54%)

7

Johns Hopkins University

USA

194 (1.53%)

8

University of Pennsylvania

USA

183 (1.45%)

9

University of California Los Angeles

USA

174 (1.38%)

10

Harvard University

USA

164 (1.30%)

11

Washington University

USA

157 (1.24%)

12

Kings College London

UK

154 (1.22%)

Table 7 presents the institutions that have contributed more than 150 publications during 2012-2021. There were 12,423 global institutions involved in the Neurology research. Among these top 12 institutions 9 are from USA, 2 are from UK and one from Canada. Mayo Clinic, USA topped the list with 331 (2.62%) publications followed by Harvard Medical School, USA with 255 (2.02%) publications, UCL Institute of Neurology, UK with 222 (1.76%) publications, Massachusetts General Hospital, USA with 206 (1.63%) publications, University of California San Francisco, USA with 205 (1.62%) publications, University of Toronto, Canada with 195 (1.54%) publications, Johns Hopkins University, USA with 194 (1.53%) publications, University of Pennsylvania, USA with 183 (1.45%) publications and University of California Los Angeles, USA with 174 (1.38%) publications.

Most preferred source titles

Table 8

Sourcetitle of publications

Rank

Source Title

No. of Publications

Percentage

Impact Factor

1

Neurology

1619

12.81

9.901

2

Brain and Development

1400

11.08

2.272

3

European Journal of Pediatric Neurology

1144

9.05

3.692

4

Epilepsy and Behavior

235

1.86

3.337

5

Journal of the Neurological Sciences

153

1.21

4.553

6

European Journal of Neurology

146

1.16

6.089

7

Pediatric Neurology

139

1.10

2.398

8

Nervenarzt

136

1.08

1.214

9

Neurological Sciences

130

1.03

3.830

10

Journal of Child Neurology

128

1.01

1.385

HHH provides the leading journals each with number of publications and impact factor. The scientific literature onneurology is spread over 1664 different web of science source journals. It reveals that Neurology the list with the highest number of publications 1619 (12.81%) and the impact factor is 9.901, followed by Brain Development with a share of 1400 (7.39%) publications and the impact factor is 2.272. European Journal of Pediatric Neurology occupies the third position with 1144 (9.05%) publications and the impact factor is 3.692. The fourth highest source title is Epilepsy and Behavior with 235 (1.86%) publications and the impact factor is 3.337, Journal of the Neurological Sciences with 153 (1.21%) publications and the impact factor is 4.553 and European Journal of Neurology with 146 (1.16%) publications and the impact factor is 6.089.

High productivity subject areas

Table 9

High productivity subject areas

S.No.

Subject

No. of Articles

Percentage

1

Neurosciences Neurology

7129

56.40

2

Behavioral Sciences

5119

40.50

3

Pediatrics

1819

14.39

4

Research Experimental Medicine

798

6.31

5

General Internal Medicine

628

4.97

6

Health Care Sciences Services

622

4.92

7

Communication

301

2.38

8

Psychiatry

299

2.37

9

Psychology

296

2.34

10

Toxicology

271

2.14

The scientific literature on neurology is spread over 91 different subjects. Table 9 shows high productivity subjects which are contributing more than 100 articles. It is found that Neurosciences Neurology has highest number of articles with 7129 (56.40%) followed by Behavioral Sciences contributing 5119 (40.50%) articles. Pediatrics occupies the third position with 1819 (14.39%) articles. The fourth highest articles belonged to the subject Research Experimental Medicine with 798 (6.31%), General Internal Medicine with 628 (4.97%) and Health Care Sciences Services with 622 (4.92%) articles respectively. 13, 14, 15

Conclusions

The current scientometric study shows that a total of 12639 articles on neurology research were published in the web of science database during 2012 to 2021. The average number of publications per year was 1263.9. Since 2021, the number of publications related to this field has grown rapidly. There was a fluctuation trend of publication during the study period. The topmost research active institution was the Mayo Clinic, USA topped the list with 331 (2.62%) publications followed by Harvard Medical School, USA with 255 (2.02%) publications and the USA has a significant research output as a country with 4232 publications. Three of the most productive journals are Neurology, Brain and Development and European Journal of Pediatric Neurology. The results of this research showed that Indian author publications was very low. Maybe neurology Indian researchers can use the results of this study to identify their research colleagues around the world and increase the publication productivity.

Source of Funding

None.

Conflict of Interest

None.

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Received : 26-12-2023

Accepted : 09-04-2024


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