The Evolution of Gastrointestinal Bleeding: A Holistic Investigation of Global Outputs with Bibliometric Analysis

Background: Gastrointestinal bleeding is one of the main presentations in emergency department admissions. Although there has been much improvement in prevention, diagnosis, and treatment recently, patients with GIB still have high morbidity and mortality. This study aimed to analyze the scientific articles on gastrointestinal bleeding published between 1980 and 2020 using statistical and bibliometric methods. Methods: Articles about gastrointestinal bleeding published between 1980 and 2020 were downloaded using the Web of Science database and analyzed using statistical methods. Network visualization maps were used to identify trending topics. Correlation studies were evaluated using Spearman’s correlation coefficient. Nonlinear regression analysis (exponential model) was used to estimate the number of articles in future years. Results: A total of 12 568 publications about gastrointestinal bleeding were found. Forty percent (n = 5033) of these publications were articles. The top 3 contributing countries to the literature were the United States of America (1646, 32.7%), the United Kingdom (433, 9%), and Germany (391, 7.7%). The top three journals with the most publications were Gastrointestinal Endoscopy (172), American Journal of Gastroenterology (165), and Digestive Diseases and Sciences (161). The effect of countries’ gross domestic product levels on article productivity on gastrointestinal bleeding was significant (r = 0. 770, P < .001). Conclusion: In this comprehensive study, a summary of 5033 articles was presented. We think that these detailed analyses will be a quick source to show the past, present, and future of this subject to those who are currently working on gastrointestinal bleeding.


INTRODUCTION
Gastrointestinal bleeding (GIB) is one of the main presentations in emergency department admissions. It has high mortality and morbidity rates and requires significant resources. Gastrointestinal bleeding is divided into 2 categories according to its location; bleeding proximal to the ligament of Treitz is called upper gastrointestinal bleeding (UGIB) and bleeding from below is called lower gastrointestinal bleeding (LGIB). Both have unique etiologies and UGIB is more common.
Upper gastrointestinal bleeding has an incidence of 50-100/100 000 and the mortality ranges between 3% and 14%. 1,2 The incidence of LGIB is 33-87/100 000. Mortality rates of LGIB are estimated to be between 2% and 4%. 3,4 Both are more common in men and their incidence and mortality rates increase with age.
The approach to GIB cases first starts with the stabilization of the patient. After initial resuscitation, identifying the source of bleeding is a clinical priority and distinguishing between upper and lower GIB can be challenging. Clinical features such as age and sex, comorbidities, medications, previous bleeding history, and type and duration of bleeding can help in the diagnosis. 5 Lower and/or upper endoscopy are usually the first tests performed and their use has recently started to increase. 6,7 These interventions help in treatment as well as in diagnosis. 7 Gastrointestinal bleeding is managed by many clinicians such as emergency medicine physicians, internal specialists, gastroenterologists, surgeons, radiologists, and hematologists because it concerns all these procedures and approaches.
Bibliometry is the analysis of scientific articles and other scientific publications on a specific subject using statistical methods. 8 The number of publications in the literature is constantly increasing and the amount of medical information doubles every 5 years on average. 9 Considering this increasing amount of information and the limited time available to researchers, bibliometric studies are of great help in making a literature review in a short time and approaching the subject with holistic dominance. In parallel with this information, studies based on statistical and bibliometric analyses have been conducted on many important medical subjects recently. [10][11][12][13] Bibliometric research can identify the most active authors, institutions, journals, the most cited influential studies, and co-citations on a subject and reveal international collaborations. 14 Although the number of global studies about GIB has increased in recent years, there is still no bibliometric study in the literature about this important subject. In this study, it was aimed to analyze scientific articles on GIB published between 1980 and 2020 using statistical and bibliometric methods.

MATERIALS AND METHODS
The Web of Science (WoS) database (by Clarivate Analytics) was used for the literature review. We used gastrointestinal bleeding (GI bleed, GI bleeding, etc.) and gastrointestinal hemorrhage (hemorrhages, haemorrhage, etc.) as keywords in the WoS search. In order not to include studies that were not directly related to the subject, publications were searched only in the title section of the studies. With this search method, all articles with gastrointestinal bleeding (e.g., GI bleeding, bleed) and gastrointestinal hemorrhage (e.g., hemorrhages, haemorrhage) in the title section were obtained and these articles were downloaded from the WoS database. Studies that were labeled in the field of pediatric research or that included keywords such as child, children, and pediatrics in the title, abstract, or keywords section were excluded. The time interval was determined as 1980-2020 (Access date: June 15, 2021). Reproducibility codes for researchers to access similar documents (search findings may vary depending on different access dates) were as follows: (Title: "gastrointestinal bleed*" OR Title: "GI bleed*" OR Title: "gastrointestinal (GI) bleed*" OR Title: "gastrointestinal hemorrhage*" OR Title: "gastrointestinal haemorrhage*" OR Title: "GI hemorrhage*" OR Title: "GI haemorrhage*" OR Title: "gastrointestinal (GI) hemorrhage*" OR Title: "gastrointestinal (GI) haemorrhage*" NOT Topic: (child*) NOT Topic: (pediatric*) Refined by: [excluding] Web of Science Categories: (Pediatrics) Timespan: 1980-2020. Indexes: SCI-Expanded, SSCI, A&HCI, CPCI-S, CPCI-SSH, BKCI-S, BKCI-SSH, ESCI.

Statistical Analysis
Statistical analyses were performed using the Statistical Package for the Social Sciences software (Version 22.0, IBM Corp.; Armonk, NY, USA) package program. Kolmogorov-Smirnov tests were used to analyze the normality distribution of the variables. To determine whether the economic power of the countries affected the productivity of world publications on GIB, the difference between the number of articles produced by countries of the world and some economic development indicators [gross domestic product (GDP) and gross domestic product per capita (GDP per capita)] of the countries was calculated using data obtained from the World Bank. Spearman's correlation coefficient was used in accordance with the data distribution to determine the correlations. 15 Visually, this relationship was evaluated with scatterplots between the logarithms of GDP and GDP per capita values and the number of published articles by countries. Nonlinear regression analysis (exponential model) was used to predict the number of publications in the coming years. The R 2 value was used to evaluate model success in regression analysis. The limit of statistical significance was accepted as P < .05. The VOSviewer package program (Version 1.6.16, Leiden University's Centre for Science and Technology Studies) was used for bibliometric network visualizations. 16 The website "https ://ap p.dat awrap per.d e" was used for world map drawing.

Development and Future Trend of Publications
The distribution of the number of published articles by years is shown in Figure 1 with a line graph. The nonlinear regression analysis results used to estimate the number of articles that could be published in 2021 and beyond are also shown in Figure 1. The compatibility of the exponential model with the data (R 2 = 0.9951) was quite high at 99.5%. According to the exponential model results, it is estimated that 304 (95% CI: 268-340) articles will be published in 2021 and 364 (95% CI: 297-431) articles will be published in 2025 ( Figure 1).

Active Countries
The distribution of the number of articles by country is shown in Figure 2. ). Cluster analysis was conducted among 55 countries that produced at least 5 articles from 115 countries producing publications about GIB and whose authors had international cooperation. According to the results of the analysis, 7 different clusters related to international cooperation were formed [cluster 1 (red color): 15 countries; cluster 2 (green color): 9 countries; cluster 3 (blue color): 9 countries; cluster 4 (yellow color): 6 countries; cluster 5 (purple color): 6 countries; cluster 6 (turquoise color): 6 countries; cluster 7 (orange color): 4 countries; Figure 3a]. The cooperation density map that was created according to the total cooperation scores calculated for the countries (the top 10 countries with the highest cooperation scores were the United States, the United Kingdom, Denmark, Italy, Canada, Spain, China, the Netherlands, Germany, and France, respectively) is presented in Figure 3b.

Correlation Analysis
There was a high level of statistically significant positive correlations between the number of articles produced by countries on GIB with GDP and GDP per capita (r = 0.770, P < .001; r = .513, P < .001). The relationships between the logarithm of the GDP and GDP per capita values of the countries and the number of articles of the countries are visually shown in Figure 4 with a scatterplot.

Active Authors
The

Active Journals
Five thousand thirty-three articles on GIB were published in 978 different journals. The first 48 most active journals producing 20 or more articles, the total number of citations by journal, and the average number of citations per article are presented in Table 1. The citation network visualization map created according to the average number of citations per article among these journals is presented in Figure 5.

Trend Topics
Four thousand three hundred forty-one different keywords were used in all of the 5033 articles published on GIB. Among these keywords, 92 different keywords that were used in at least 15 different articles are shown in Table 3. The network visualization map of the clustering analysis results between these keywords is shown in Figure 6  In 2020, 288 articles were published and it was determined that there was an exponentially increasing trend in the number of articles in recent years. According to the results of nonlinear regression analysis, the number of articles will continue with an increasing exponential trend.
When we looked at the distribution of active research areas on GIB, gastroenterology and hepatology departments were leading with 43.1%. Later, we can say that departments that were mostly related to treatment parts such as surgery, radiology, nuclear medicine, medical imaging, and pharmacology came to the fore. Emergency medicine had a low level of 2.4%. Although almost all patients with GIB first present to the emergency department, this may be because treatment protocols require a multidisciplinary approach, and long-term follow-up of patients is completed by other departments. Another reason for this may be that the emergency department is newer compared with other departments such as internal medicine. Considering that the emergency department offers many resources and data for studies on this subject, we can say that will make up a larger portion of the whole with time.
Looking at the distribution of publications in terms of production of GIB articles in the most active countries, 17 of the first 20 countries that were most active in article production on GIB were developed countries; the other 3 countries (China, Turkey, and India) were developing countries. Although these 3 countries were developing, each had a large economy. In addition, when the results of the correlation analysis were examined in our study, a significant correlation was found between article production and GDP, which is one of the indicators of economic development. Similar to the bibliometric studies conducted on many different medical subjects in the literature, it has been observed that economic power is effective in publication production. 39 A moderately significant correlation was determined with GDP per capita. When the scatter plots were examined, there was a higher correlation between article productivity and GDP rather than GDP per capita. The reason for this is that although some countries [Luxembourg (n = 0), United Arab Emirates (n = 3), Qatar (n = 4), Iceland (n = 9), and Hong Kong (n = 14)] have high GDP per capita, they do not have scientific article productivity. This shows that in addition to the economic power of the countries, other development indicators can also be effective in the production of articles. When the co-authorship cooperation of countries on GIB was examined in the density map, which was created according to the total cooperation scores between countries, the fact that countries with geographic neighbors (China-Japan-South Korea-Singapore), (France--Belgium), (Denmark-the Nethe rland s-Swi tzerl and), (Ital y-Tur key-G reece -Roma nia-A ustri a) are in the same cluster shows that geographic proximity has a significant effect on article production. When the analyzed articles were evaluated according to the total number of citations they received, the most cited study was published in Gut by Rockall et al 17 on "Risk assessment after acute upper gastrointestinal haemorrhage" in 1996. The aim of this study was to reveal the relative importance of risk factors for mortality after acute UGIB and to formulate a simple numerical scoring system that categorized patients according to risk. This study included 4185 patients, and as a result, age, shock status, comorbidities, diagnosis, major recent bleeding, and rebleeding were all individual mortality indicators. 17 In addition, the fifth most effective study was found as the "Incidence of and mortality from acute upper gastrointestinal haemorrhage in the UK (1995)," and this article was also written by Rockall et al. 21 The second most cited study was Villanueva et al's 18 "Transfusion strategies for acute upper gastrointestinal bleeding," which was published in the New England   Journal of Medicine in 2013. This study compared the liberal transfusion strategy with the restrictive transfusion strategy in terms of efficacy and safety, and as a result, it was seen that the restrictive transfusion strategy improved the outcomes in acute UGIB.
The third most cited study was "Risk of upper gastrointestinal bleeding and perforation associated with individual nonsteroidal anti-inflammatory drugs" by Rodriguez et al 19 and was published in The Lancet in 1994. In this study, non-steroidal anti-inflammatory drugs (NSAIDs) and other factors that increase the risk of UGIB were examined, and it was emphasized that NSAIDs should be used carefully in people with an increased risk of GIB such as older patients, smokers, and those with a history of peptic ulcers. 19 When the studies were evaluated according to the average number of citations per year, the most efficient article was Villanueve et al's 18  According to the co-citation numbers of the 5033 articles analyzed, the most influential studies are Rockall et al, 17 Rockall et al, 21 Blatchford et al, 24 Barkun et al, 37 Longstreth, 33 Forrest et al, 38 van Leerdam, 36 Longstreth, 29 respectively. We can suggest that physicians and researchers who want to publish on the subject of GIB should first examine these publications. These will be of great help in identifying tricks or areas for improvement in their work/publication that should be carefully approached.
Clusters of keywords were analyzed to identify trending topics. It was determined that the trend topics studied in recent years were atrial fibrillation, esophageal varices, anticoagulants, heart failure, left ventricular assist devices, Glasgow-Blatchford scores, video capsule endoscopy, liver cirrhosis, warfarin, risk assessment, and Rockall scores. The most mentioned keywords were aspirin, NSAIDs, clopidogrel, hemostasis, epidemiology, heart failure, treatment, left ventricular assist device, risk assessment, nonsteroidal anti inflammatory drugs, gastrointestinal endoscopy, outcomes, and double-balloon enteroscopy. In parallel with the citation analysis, keyword analyses also showed that epidemiology, drug interactions, and new treatment modalities were hot topics.
When we examined the literature in detail, no previous bibliometric study about GIB was found. In our study, all of  bleeding. Indicator shows trend keywords from blue to red (blue-gree n-yel low-r ed). The circle size increases with the number of times the keyword is used.
the scientific articles published on GIB between 1980 and 2020 were analyzed comprehensively. To the best of our knowledge, our study is the first detailed bibliometric research on this subject. The presence of keyword analysis, trend topic analysis, cluster analysis, correlation, and regression analyses in our study, apart from citation analysis, is another superior aspect of our study.
To mention the limitations of our study, only the WoS database was used. Our analyses do not include other databases such as Scopus, PubMed, and Google Scholar. While making this choice, the WoS database's features such as having a wide network of journals, already containing many important studies from PubMed, Scopus, and Google Scholar, and providing enough data to allow for many analyses such as citation and co-citation analysis were taken into account. 41 When we looked at the literature, it was seen that the WoS was used in most bibliographic studies. [10][11][12][13] We shared a summary of 5033 articles published between 1980 and 2020 in this wide bibliometric study on GIB, which has had an increasing trend in the number of articles published in recent years. We think that these detailed analyses will be a guide for people who are interested in this subject. In addition, it will be a quick resource to show the past, present, and future of this subject to those who are currently working on GIB. It will also help those planning new studies to see which topics are trending, which topics are currently prominent, and which topics need to be studied.
Ethics Committee Approval: Ethics committee approval was not obtained for this study as it was web-based and did not involve any human or animal.
Peer-review: Externally peer-reviewed. Funding: This study received no funding.