Introduction

Anaphylaxis is a serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death. Severe anaphylaxis is characterized by potentially life-threatening compromise in breathing and/or the circulation and may occur without typical skin features or circulatory shock being present [1]. Recent studies have confirmed that the incidence of anaphylaxis has increased and poses a significant burden on population health and healthcare settings [2], [3]. With a better understanding of anaphylaxis, more and more articles have been published. However, the information in the database will also be more complex, making it difficult for clinicians to find most needed and valuable research.

Bibliometric analysis is the process of extracting measurable data through statistical analysis of published research studies, which can provide researchers with important messages in a specific field [4]. Citation analysis is one of bibliometric analysis methods that has been used to quantify the relative significance of a scientific article by examining the citations attributed to that paper. A thorough bibliometric analysis of the top 100 most cited articles can help the understanding of disciplinary development and future directions of a research field [5].

According to document index, some allergic diseases have been explored by bibliometric analysis, such as asthma [6], allergic rhinitis [7], and food allergy [8]. However, no bibliometric analysis of anaphylaxis was conducted based on our knowledge. Thus, this study aimed to identify the top 100 most cited articles in anaphylaxis and analyze their bibliometric characteristics.

Methods

Data sources and search strategies

Web of Science Core Database was chosen as the database to perform the literature source and bibliometric analysis for this study. The top100 most cited articles in anaphylaxis were retrieved from the database Web of Science Core Collection on November 20, 2021, with the following strategy: topic = anaphylaxis, from 1991 to 2021, no language limitation. Only article and review were included in analysis. Abstracts, editorials, proceeding papers, and book chapters articles were excluded. A total of 14,096 publications were retrieved from the Web of Science Core Database. Articles were ranked based on the total number of citations. If articles with the same total citation, recent articles were ranked higher.

Data extraction and bibliometric parameters

Research focusing on anaphylaxis or regarding anaphylaxis as a main part were included in this study. The two researchers examined the articles independently for qualify and finally reached an agreement on the list of the top 100 most cited articles. Then the top 100 list was imported into Biblioshiny and VOSviewer for bibliometric analysis.

Biblioshiny is a new advanced tool of bibliometric analyses [9, 10]. In this study, it was  used it to perform a basic bibliometric analysis. To obtain more comprehensive information of the result based on co-occurrence which can visualize the research hotspots and classification, the study also constructed bibliometric maps by VOSviewer. Bibliometric indicators included year of publication, total number of citations and average citations per year (ACY), journal of publication and impact factor (IF), countries, institutes, and authors and co-occurrence network.

Statistical analysis

SPSS 19.0 was used for the statistical analysis. The Kolmogorov–Smirnov test was used to analyze the normal distribution of data. Spearman’s correlation was used to evaluate the association between total number of citations, ACY, IF, and length of time since publication. A p-value < 0.05 was accepted as statistically significant.

Ethical statement

This research did not involve intervention or data collection in animal experiments or clinical trials. Thus, approval from an ethical committee was not needed.

Results

The top 100 most cited articles are listed in Table 1, sorted in descending order according to the number of citations. In the top 100 list, 82 were articles and 18 were reviews.

Table 1 List of the top 100 most cited articles in anaphylaxis(1991-2021)
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Year of publication

The top 100 most cited articles were published between 1991 and 2017. The number of articles published in each 3-year interval followed normal distribution (p = 0.682). The largest number of articles published in a single interval was 25, which occurred in 2006–2008.

Figure 1 shows the number of articles published in each 3-year interval.

Fig. 1
figure 1

The number of articles published in each 3 year interval

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Citations

The total citations of articles in each 3-year interval are shown in Fig. 2. The total number of citations in each 3-year interval followed normal distribution (p = 0.962). The largest total number of citations in each 3-year interval was also 2006–2008. We identified a positive correlation between total citations and the number of articles published in each 3-year interval (r = 0.921, p < 0.01). Total citations of the 100 articles were between 156 and 1243, with a mean of 278.02. Top 10 most cited articles accounted for 24.44% (n = 6796) of the total citations. Average citations per year (ACY) of the top 100 articles were from 5.61 to 68.13, with a mean of 18.54. Six of the top 10 most cited articles according to total citations still ranked in the top 10 list according to average citations per year. We observed that the most cited article among the top 100 list was a study by Sampson HA with the following title: “Fatal and Near-Fatal Anaphylactic Reactions to Food in Children and Adolescents” published in New England Journal of Medicine 1992.

Fig. 2
figure 2

The number of citations in each 3 year interval

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Journal of publication

Journals and their impact factor are listed in Table 2.

Table 2 List of journals from the top 100 articles
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The top 100 articles were published in 34 different journals. The Journal of Allergy and Clinical Immunology published the most (n = 41), followed by Allergy (n = 9) and Clinical and Experimental Allergy (n = 5). 77% articles of top 100 were published in 11 journals. We determined that the IF of these 34 journals was from 1.131 to 91.253 (according to Clarivate Analytics 2020). There was no correlation between IF and number of publications (p > 0.05).

Figure 3 shows the dynamic changes of articles published in major journals. Since the middle 1990s, the publications of The Journal of Allergy and Clinical Immunology began to increase rapidly compared with other journals.

Fig. 3
figure 3

Dynamic changes in the number of articles in major journals

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Correlation analysis between citations, ACY, IF, and publication time

The correlation analysis for the total number of citations, ACY, IF, and length of time since publication in the top 100 list revealed a positive correlation between total number of citations and ACY (r = 0.670, p < 0.01), and between total number of citations and IF (r = 0.219, p < 0.05), whereas a negative correlation was observed between ACY and length of time since publication (r = -0.697, p < 0.01). There was no correlation between total number of citations and length of time since publication or between ACY and IF or between length of time since publication and IF (Fig. 4).

Fig. 4
figure 4

Correlation analysis between citations, ACY, IF, and publication time

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Countries collaboration, affiliations, and authors

The data extracted from web of science indicated that the corresponding authors of the top 100 articles were from 13 different countries (Fig. 5). Most of the top 100 cited articles were from the USA (n = 46), followed by Canada (n = 10), Australia (n = 8), and France (n = 8).

Fig. 5
figure 5

Corresponding author’s country

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Figure 6 shows the country collaboration map worldwide generated by the Biblioshiny.

Fig. 6
figure 6

Country collaboration map

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There were 219 pairs of collaborating countries worldwide, of which the top 3 were the USA and Canada with 13 collaborations, followed by the USA and Germany with 10 collaborations, as well as the USA with UK with 10 collaborations. Collaboration Network according to the Biblioshiny is shown in Fig. 7. We observed that the collaboration network had two clusters, one was the continental European countries, and the other mainly included the USA, Canada, Australia, and UK.

Fig. 7
figure 7

.Collaboration network

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As to the most relevant affiliations according to Biblioshiny, University of Manitoba published the most articles (n = 21), followed by Harvard University, University of Cincinnati (n = 13), and University of Florida (n = 10) (Table 3).

Table 3 List of the top10 affiliations in the number of articles
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The top 10 most prolific authors demonstrated by Biblioshiny was that Simons FER from University of Manitoba produced the most top-cited articles in anaphylaxis(n = 14), followed by Sampson HA(n = 8), Sheikh A(n = 7), Lieberman P(n = 6), Worm M(n = 6), Thong BY (n = 5), Ardusso LRF(n = 4), Kemp SF(n = 4), Laxenaire MC(n = 4), Lockey RF(n = 4).

Figure 8 shows the details of the top 10 authors and their productions over time. The larger the circle, the more articles published. The deeper the color, the more citations.

Fig. 8
figure 8

Top-autors’ production over the time

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The analysis of co-occurrence network

Apart from searching term “anaphylaxis,” authors keywords and keywords plus extracted from the top 100 articles were analyzed by VOSviewer (Fig. 9). According to Fig. 9A, different colors represent different clusters and the size of the ball reflects the frequency of keywords. It was observed that the research focus was classified into three clusters, marked with red, blue, and green, respectively. In addition, the color of keywords corresponds to the average publication year as shown in Fig. 9B. The recent keywords after 2005 mainly included “drug allergy,” “adrenaline,” “prevalence,” “diagnosis,” and “management.”

Fig. 9
figure 9

.Co-occurrence network

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Recent articles

No articles published after 2017 were observed in the top 100 list. In order to better show the recent research hotspots, we retrieved the top 10 most cited articles published from 2018 to 2021 (Table 4). The total citations of the top 10 articles were from 58 to 151, and ACY of them were between 14.5 and 102. Nine of the top 10 most cited articles were original articles, and one was review. The correlation analysis for the total number of citations, ACY, IF, and length of time since publication in the top 10 list revealed a negative correlation between ACY and length of time since publication (r = − 0.782, p < 0.01). However, there was no correlation between the other parameters, which was different from the results of top 100. The research hotspots of the top 10 articles were COVID-19 vaccine (n = 3), pathogenesis (n = 3), perioperative anaphylaxis (n = 1), diagnosis (n = 1), and others (n = 2).

Table 4 List of the top 10 most cited articles in anaphylaxis(2018-2021)
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Discussion

Bibliometric analysis explores the characteristics of published articles based on specific and reliable parameters [11]. The top 100 most cited articles may be the highly recognized articles in a certain area, and analysis of these articles may quantitatively determine primary research concerns and provide information about dynamic research changes.

Among the top 100 list, the largest number of articles published in a single interval is between 2006 and 2008, which may be mainly attributed to the publication of the article in 2006 entitled “Second symposium on the definition and management of anaphylaxis: summary report–Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium” with 314 citations. Even though anaphylaxis was first described around 100 years ago, there was no universal agreement on its definition or criteria for diagnosis, which greatly hampered research into the epidemiology, pathophysiology, and management of anaphylaxis. This article provided a definition of anaphylaxis and clinical criteria for diagnosis, which became a landmark in anaphylaxis research. Subsequently, several important biomarkers were confirmed, such as platelet-activating factor [12] and tryptase [13]. In addition, owe to the technological progress and clinical research, galactose-α-1,3-galactose [14] and extensive skin disease with mastocytosis [15] were also confirmed as the important risk factors of anaphylaxis.

The number of citations generated by a paper is an indicator of the impact on the research field, but not necessarily the quality and eminence of it [16]. It would accumulate over time, so the time strongly influenced the impact assessment through citation analysis. Garfield demonstrated that older papers had more chance to be cited [17], and even the most cited papers had no citation when they were just published. Therefore, we use ACY to try to reduce this bias; however, we illustrated a positive correlation between total citations and ACY among top 100 list. It indicates that there may be a positive correlation between ACY and total citations over time.

Our analysis showed that the majority of the top 100 articles were published in The Journal of Allergy and Clinical Immunology followed by Allergy and Clinical and Experimental Allergy.

We found that there was no correlation between IF and number of articles, which indicated that IF may not represent the production of journals in top 100 list. Such findings were similar to bibliometric analyses of allergic rhinitis [7]. The correlation analysis also showed a positive correlation between total number of citations and IF, whereas a negative correlation was observed between ACY and length of time since publication. It may be explained by the inherent bias that researchers tended to choose high impact factor journals for citation and younger articles have higher ACY.

The publication of papers in different countries may reflect the influence of the country in the field of anaphylaxis to some extent. We identified the corresponding authors from 13 different countries of the top 100 most cited articles. Simons FER from University of Manitoba published the most articles, while most articles were from the USA. The European and the North America are two major research collaboration networks. Despite the relatively high prevalence in these areas, different degrees of economic growth might also explain this phenomenon.

Co-occurrence of keywords analysis, aiming to investigate the co-occurring relationships between keywords in a set of publications, can show the different research hotspots and topics [18]. According to the co-occurrence network by VOSviewer, we found that cluster 1 (red) was mainly about the epidemiology and management, cluster 2 (blue) mainly focused on the risk factor and treatment, cluster 3 (green) mainly reflected the assessment and diagnosis of anaphylaxis (Fig. 9A). According to Fig. 9B, we can see that the recent hotspots mainly on drug allergy, optimizing treatment as well as management, and improving clinical diagnosis.

Although co-occurrence analysis has shown the research hotspots in recent years, the latest research hotspots may not be shown as no articles published after 2017 in top 100 list, so we retrieved the top 10 most cited articles published from 2018 to 2021. We found that the number of articles related to COVID-19 vaccines has increased sharply (Table 4), as the COVID-19 vaccination is an essential way to control the current pandemic situation. Although anaphylaxis due to a vaccine is rare, it can lead to fear and undermine public confidence [19]; therefore, the importance of vaccine safety research is self-evident.

Although we spared no effort to eliminate potential defects in this bibliometric analysis, some limitations were inevitable. First, although Web of Science Core Database is a recommended database for clinical research and a relatively reliable source, the citations of articles may be insufficient and affect the results of bibliometric analysis. Second, the definition of anaphylaxis has been controversial for many years; therefore, when we regard the key word “anaphylaxis” as the search subject word, we may miss some relevant articles. Besides, citation ranking may not be intended to measure quality, but rather a degree of recognition. Low citation numbers may not represent low research value, and historical high citation numbers also cannot represent the longtime influence in the future. Despite these defects, the data presented here provide insight into the outline of anaphylaxis research over the past 30 years. In conclusion, this study identified the top 100 most cited articles in anaphylaxis and showed their bibliometric characteristics, which may pave the way for further study.