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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 17  |  Issue : 3  |  Page : 134-140

Pediatric hyperthyroidism research: A scientometric assessment of global publications during 1990–2019


1 Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 CSIR-National Institute of Science, Technology and Development Studies, New Delhi, India

Date of Submission21-Oct-2020
Date of Acceptance29-Nov-2020
Date of Web Publication20-Jan-2021

Correspondence Address:
Prof. Devi Dayal
Endocrinology and Diabetes Unit, Department of Pediatrics, Advanced Pediatrics Center, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/trp.trp_67_20

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  Abstract 


Background: A systematic mapping of research in pediatric hyperthyroidism (PHT) is unavailable.
Aims and Objectives: To provide a comprehensive assessment of PHT research over the past three decades.
Materials and Methods: The data on publications in PHT were retrieved from the Scopus database using a defined search strategy, and analyzed using select bibliometric indicators.
Results: During 1990-2019, global research in PHT registered 8.8% and 150.7% average annual and 15-year cumulative growth respectively, and averaged 30.6 citations per paper. Of the 111 participating countries, the USA leads the ranking with 28.9% share, followed by Italy, UK and Germany with 7.8%, 7.6% and 7.5% share, respectively. The number of participating organizations and authors was 555 and 1117 respectively. National Institute of Health, Bethesda, USA, INSERM, France and John Hopkins University, USA were the three most productive organizations. The most productive authors were F. Vargas, S. A. Rivkees, and F. De Luca, and the most productive journals were the Journal of Pediatric Endocrinology and Metabolism, Journal of Clinical Endocrinology and Metabolism, and Thyroid.
Conclusions: The PHT research is largely conducted in developed countries of the North-American and European regions. The disparity in research needs to be addressed by fostering collaboration, and strengthening of institutional research capacities. This is the first sketch of global research architecture in PHT.

Keywords: Bibliometrics, global publications, Graves' disease, pediatric hyperthyroidism research, scientometrics


How to cite this article:
Dayal D, Gupta BM. Pediatric hyperthyroidism research: A scientometric assessment of global publications during 1990–2019. Thyroid Res Pract 2020;17:134-40

How to cite this URL:
Dayal D, Gupta BM. Pediatric hyperthyroidism research: A scientometric assessment of global publications during 1990–2019. Thyroid Res Pract [serial online] 2020 [cited 2021 Oct 28];17:134-40. Available from: https://www.thetrp.net/text.asp?2020/17/3/134/307561




  Introduction Top


Hyperthyroidism is an uncommon endocrine condition in children but is associated with significant morbidity resulting from the damaging effects of thyroid hormones excess on the function of various organ systems in the body. The exact prevalence of pediatric hyperthyroidism (PHT) is unknown but approximates the prevalence of Graves' disease (GD) which accounts for more than 95% of all PHT cases.[1] The prevalence of PHT is 1 in 10,000 in USA children and about 5% of all GD cases in the country.[1] Based on the number of new prescriptions of antithyroid drugs (ATD) by age group, a study from the USA estimated the incidence of PHT as 0.44/1000 and 0.59/1000 among children aged 0–11 and 12–17 years, respectively, peaking at 10–15 years.[2] According to recent estimates, the overall incidence of PHT appears to be increasing.[1]

Although PHT is a well-researched disease, there are several issues that need further research.[1] The epidemiology of PHT and hence the disease burden in several countries remains undefined.[1] The underlying reasons for a low rate of remission of only about one-fourth to one-third of all cases, are unknown.[3],[4] Further, it is not known why children with GD are more prone to relapses as compared to adults.[5] In addition, the ATD regimens are still evolving although a control of hyperthyroid state is achievable in a majority of PHT patients.[6],[7] Despite an increasing use of definitive treatment with radioiodine ablation or thyroidectomy, the best timing for the definitive therapy as well as characteristics of patients who are more likely to benefit from an early definitive therapy, is unclear.[8],[9] The optimum treatment for the low bone mineral density and the effects of ATD on bone health are less well studied in children.[10] Furthermore, there are scarce data on optimal management of ophthalmopathy in childhood GD.[11] Finally, despite a tremendous progress in achieving “control” of hyperthyroid state, a cure remains elusive in PHT. A precise bibliometric assessment of the research on PHT is therefore required to identify research gaps and guide further research.

There is no bibliometric study available on research output in PHT. Previous studies on thyroid research did not separately examine the PHT research.[12],[13],[14] We therefore planned to conduct a qualitative as well as quantitative assessment of global publication output over the past three decades with an aim to address the lack of a comprehensive assessment of research in this field.

Objectives

We aimed to provide a scientometric assessment of global research in PHT during 1990–2019, using select quantitative and qualitative bibliometric indicators on publications covered in Scopus multidisciplinary database. The study focuses on distribution of publications by type and source, global publication growth, research output and impact of top countries, organizations and authors, international collaboration, broad subject areas of research, media of research communications, and bibliographic characteristics of highly cited publications (HCPs).


  Materials and Methods Top


The publications on PHT during 1990–2019 were identified in the Scopus database (http://www.scopus.com), using a defined search strategy. Two combinations of keywords were searched in “Keyword” and “Title” (Article Title) tags, and the search output was confined to the period 1990–2019, as shown below:

KEY (hyperthyroidism and (child* or pediatr* or toddler or kid* OR infant) or TITLE (hyperthyroidism) and (child* or pediatr* or toddler or kid* OR infant) and PUBYEAR >1989 and PUBYEAR <2020.

This search was further refined by country name one by one to generate the publication output of 10 most productive countries. The publications were further analyzed by broad subjects, collaborating countries, author-wise, organization-wise, and journal-wise, etc., using analytical provisions of the Scopus database. We used complete counting method, wherein every contributing author or organization covered in multiple authorship publications is fully counted. The names of the authors were standardized to avoid spelling errors in names and initials, similar to our previous bibliometric studies.[15],[16],[17] The issue of synonyms or homonyms in authors' names was sorted out using other specific fields such as author affiliations. The indices of qualitative assessment included citations per paper (CPP), relative citation index (RCI), and H-index (HI). The CPP was defined as the total number of citations divided by the total number of publications. The RCI was calculated by dividing the number of citations received by the average number of citations an article usually receives in that particular field. The number is then benchmarked against the median Relative Citation Ratio for all NIH-funded papers. HI or Hirsch index is defined as the maximum value of h such that the given author/journal has published h papers that have each been cited at least h times. Activity index was used to depict changes in research activity over time. The 30-year study period was divided into two 15-year time periods to understand the changes in growth rate and other metrics. Citations to publications were counted from date of their publication till May 12, 2020.


  Results Top


General profile of publications

The total number of publications on PHT was 3493 over the 30-year study period, and showed an average annual growth of 8.8%, increasing from 50 in 1990 to 199 in 2019 [Figure 1]. The absolute growth rate was 150.7%, as cumulative publications increased from 996 during 1990–2004 to 2497 during 2005–2019. The average CPP was 30.6, which showed a marginal decline from 31.8 during 1990–2004 to 30.1 during 2005–2019 [Figure 1]. Original articles and reviews contributed the major publication share of 66.4% and 21.7%, respectively, followed by letters, conference papers, notes, short surveys, and editorials (from 1.4% to 4.0%) and book chapters, erratum, and undefined (from 0.03% to 0.3%). Only 251 (7.2%) publications were funded by 158 funding agencies. The funded publications had higher CPP as compared to nonfunded (51.6 vs. 30.6). National Institutes of Health, USA (57 papers); Bristol Myers Squibb (38 papers); AstraZeneca, Pfizer, and Roche (19 papers each); National Natural Foundation of China and Novartis (17 papers each); Merck (15 papers); and Eli Lilly and Co. and Bayer (12 papers each), were the major funding agencies.
Figure 1: Number of citations (a), and number of publications, citations per paper and funded papers (b) on pediatric hyperthyroidism research during 1990–2019

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Most productive and impactful countries

Research on PHT was unevenly carried out in 111 countries; 56 contributed 1–5 publications each, 11 contributed 6–10 publications each, 22 contributed 11–50 publications each, 11 contributed 51–100 publications each, 5 contributed 101–300 each, and 1 contributed 1011 publications. The most productive countries were the USA, Italy, the UK, and Germany, with publication share of 28.9%, 7.8%, 7.6%, and 7.5%, respectively [Table 1]. Between 1990–2004 and 2005–2019, the USA, China, Turkey, India, Canada, and the UK increased their publication share by 1.0%–5.2%, as against a decrease in countries, namely Spain, Italy, France, Japan, and Germany. Five countries registered RCI higher than their group average of 1.5: Canada 2.9, the UK 1.9, France 1.8, the USA 1.8, and Germany 1.6. The share of international collaborative papers among the top 11 countries varied from 12.3% to 58.6%, with an average of 26.9% [Table 1].
Table 1: Contribution of the top 11 countries in pediatric hyperthyroidism research during 1990-2019

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Intercountry research collaboration

All the top countries had one-to-one collaboration; the USA, Germany, and France showed the largest, whereas India, Turkey, and China showed the least number of collaborative linkages [Supplementary Table 1][Additional file 1]. The USA collaborated with Canada, Italy, Germany, and the UK in 44, 42, 40, and 37 publications, respectively [Supplementary Table 1].

Subject-wise distribution of research output

Medicine contributed the largest publication share and CPP of 90.3% and 31.5, respectively, as compared to other research subjects. All subject areas showed an increase in research activity except for biochemistry, genetics, and molecular biology [Supplementary Table 2][Additional file 2].

Type of hyperthyroidism

The largest share of research (694 publications, 19.9%) was conducted on GD, followed by thyroiditis (371 papers, 11.8%), thyroid storm (11 papers, 0.4% share), and hyperfunctioning thyroid nodules (5 papers, 0.2%). The publications share showed a marginal decrease in GD from 21.9% to 19.0% during the two 15-year time periods, as against an increase in rest of the areas.

Significant keywords

Eighty-one keywords were identified from the publications on PHT as indicators of research trends and are listed in [Supplementary Table 3][Additional file 3] in decreasing order of their frequency of occurrence in literature during 1990–2019.

Most productive organizations

Of the 551 participating organizations, 264 published 1–5 papers each, 157 published 6–10 papers each, 99 organizations 11–20 papers each, and 31 organizations 21–43 papers each. Among the top 50 organizations, 23 were from the USA; 7 from Italy; 4 from France; 3 from Germany; 2 each from Sweden, Spain, and The Netherlands; and 1 each from Australia, Canada, Denmark, Israel, Japan, Taiwan, and the UK [Supplementary Table 4][Additional file 4]. The contribution of the top 50 organizations varied from 17 to 43 publications per organization; together, they contributed 33.9% (1186) of publications share. Nineteen organizations registered their publication output above the group average of 23.7, while 16 registered their CPP and RCI above the group average of 114.82 and 3.75, respectively. [Table 2] shows the 10 most productive and 10 most impactful organizations.
Table 2: Top 10 most productive and top 10 most impactful organizations in global pediatric hyperthyroidism research during 1990-2019

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Interinstitutional collaboration

The top 4 organizations that registered the highest collaboration linkages were INSERM, France; Memorial Sloan Kettering Cancer Center, USA; Universite de Paris, France; and Hôpital Robert-Debré AP-HP, France, whereas Universita di Pisa, Italy; Universita degli Studi di Messina, Italy; and Charite Universitatsmedizin Berlin, Germany, recorded the least number of linkages [Supplementary Table 5][Additional file 5]. The institution pairs that recorded the largest number of linkages were INSERM, France, and Universite de Paris, France; INSERM, France, and Hôpital Universite de Paris, France, and Hôpital Robert-Debré AP-HP, France; and Memorial Sloan Kettering Cancer Center, USA, and University of Texas MD Anderson Cancer Center, USA, with 17, 14, 10, and 8 linkages, respectively [Supplementary Table 5].

Most productive and impactful authors

A total of 1117 authors participated in global PHT research; 1038 published 1–5 papers each, 58 published 5–10 papers each, 20 published 11–20 papers each, and 1 published 24 papers. Twenty authors registered their publication output above the group average of 10.4, whereas nine registered their CPP and RCI above the group average of 62.7 and 2.0, respectively [Table 3].
Table 3: Most productive and most impactful authors in pediatric hyperthyroidism research during 1990-2019

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Medium of research communication

Of the total research yield, 99.0% (3459 publications) appeared in journals, 0.7% (24 publications) in book series, 0.2% as books, and the rest as trade publications or undefined. Of the 1258 journals which reported 3461 articles, 1143 published 1–5 papers each, 82 published 6–10 papers each, 21 published 11–20 papers each, 9 published 21–50 papers each, 2 published 51–100 papers each, and 1 published 195 papers. The top 50 most productive journals published 28.4% of the research output that appeared in journal medium during 1990–2019, which showed a decrease from 31.2% to 27.3% between 1990–2004 and 2005–2019. The top 10 most productive and the most impactful journals are shown in [Table 4].
Table 4: Most productive and most impactful journals in global pediatric hyperthyroidism research, 1990-2019

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High impact publications

Only 190 (5.4%) publications received 100–6736 CPP; their total citations were 60,092, averaging 316.2 CPP. The number of citations was highly skewed; 121 papers were cited 100–200 times, 31 papers 201–300 times, 18 papers 201–300 times, 11 papers 301–500 times, 11 papers 501–1000 times, and only 9 were cited 1001–6736 times. The HCPs were largely contributed by institutions in the USA [Supplementary Table 4]. The major authors of HCPs were P. Laurberg, J. D. Wolchok, C. Robert, M. B. Zimmermann, D. S. Cooper S. A. Rivkees, A. Pinchera, P. Vitti, M. T. Cllins, and G. Y. H. Lip [Supplementary Table 6][Additional file 6].

The Journal of Clinical Endocrinology and Metabolism, New England Journal of Medicine, Thyroid, and Journal of Clinical Oncology published 25, 9, 8, and 8 HCPs, respectively, while Clinical Endocrinology, European Journal of Endocrinology, The Lancet, Lancet Oncology, Endocrine Reviews, and Annals of Oncology published 5 HCPs each [Supplementary Table 7][Additional file 7].


  Discussion Top


Our analysis shows that research in PHT has shown a remarkable growth over the last three decades and has led to a better understanding of several aspects of the disease and has helped in improving the lives of children suffering from hyperthyroidism.[1] However, the PHT research landscape is dominated by North American and Western European countries. None of the developing countries were among the top productive or impactful countries in PHT research, despite a disease burden almost similar to what is seen in the developed countries.[1],[18] A particularly concerning observation was the lack of collaboration between high-resource and low-resource countries. Most of the intercountry collaborative linkages were observed between high-resource countries. As quality research requires financial support, a collaboration between resourceful and resource-constrained countries may help improve overall research in PHT.[19]

Another important finding was the decrease in quality of research as indicated by CPP of publications over the study period. One of the reasons could be the small proportion of funded research. It is well known that the funded research produces better quality research measured by the citation impact of publications.[19] The CPP of funded publications was much higher as compared to nonfunded publications (51.6 vs. 30.6).

Several aspects of PHT such as the global disease burden, reasons for frequent relapses, effects on bone health, timing of definitive therapy, and optimal therapy of eye disease in GD need quality research. To conduct such high-quality research activities, there is a need for commitment by the national governments, research organizations, professional bodies, and researchers involved in the care of children with hyperthyroidism. The way forward is to increase financial support, improve research collaboration between developing and developed countries, and strengthen the research capacity of institutions in the resource-constrained setups.[20] Although individual researchers in the developing countries also need support for enhancing their research capacity, the long-term impact and sustainability of individual-level research remains poor despite apparent promising short-term outcomes.[20] The resource crunch faced by researchers in low-income countries often limits their research endeavors resulting in a low-impact research yield despite a high-volume thyroid practice.[19],[21],[22],[23],[24]

A few limitations of the current bibliometric study need discussion. The study is based on the publications indexed in the Scopus database only and could have missed some data on PHT. It has been suggested that a simultaneous search in the three major medical databases, i.e., Scopus, PubMed, and Web of Science, may improve data capturing but is cumbersome to conduct.[25],[26] We chose Scopus for its larger content coverage, search analysis tools, and funding information as compared to PubMed or Web of Science.[25],[26] A vast majority of bibliometric studies use a single database.


  Conclusion Top


The research landscape in PHT is dominated by developed countries in the North American and European regions. There is a disparity in PHT research between resourceful and resource-poor countries despite similar disease burden in different countries. There is a need to address the research gaps through collaboration and strengthening of national and institutional research capacities to overcome current and future health challenges posed by PHT. To the best of our knowledge, our study provides the first mapping of global PHT research architecture.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]


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