INTRODUCTION

Gastroenterology is a vital field of medical science focused on the digestive system and its disorders. In 2019, there were 7.32 billion cases of digestive diseases globally, with a prevalence of 2.86 billion cases, and 8 million deaths reported across 204 countries¹. Given the high morbidity and mortality associated with these diseases, research in this field is of paramount importance.

In Japan, gastrointestinal diseases represent a major health concern. According to the “Summary of the Patient Survey, 2020” by the Ministry of Health, Labour and Welfare, gastrointestinal diseases accounted for 1,270,800 outpatient cases, representing 17.8% of all outpatient cases, the highest among all categories². Gastrointestinal cancers account for approximately half of all cancer incidences and deaths in Japan³. With early detection and treatment of gastrointestinal cancers being a major research priority, Japan has been a global leader in endoscopic technology. Techniques such as Endoscopic Submucosal Dissection (ESD), which developed in Japan⁴, have significantly contributed to the early detection and treatment of gastrointestinal cancers.

Understanding the collaborative networks among researchers in Gastroenterology is essential for gaining insights into the development and dissemination of knowledge within this field. Co-authorship network analysis is a powerful tool for examining the structure and dynamics of scientific collaboration. By analyzing co-authorship patterns, key researchers, influential research groups, and the overall connectivity within the research community can be identified.

This study aims to analyze the co-authorship network in Gastroenterology research from 2000 to 2023, using data from the Web of Science (WoS). The dataset comprises 18,855 articles, offering a comprehensive overview of the collaborative landscape in this field over the past two decades.

The findings of this study will enhance our understanding of collaborative relationships among gastroenterology researchers. By identifying key players and groups, especially in areas where Japan excels, such as endoscopic technology, this research can help foster more effective collaborations and advance the field further. Additionally, the insights gained can be applied to other medical research areas, broadening our understanding of scientific collaboration.

METHODS

The present study investigates the co-authorship patterns in Gastroenterology research papers. I utilized the WoS database, conducting a “Topic search” with the keyword “Gastroenterology” to analyze a total of 18,855 articles published between 2000 and 2023 (as of August 2024). In this analysis, I examined who collaborated with whom in co-authoring these papers. I conducted network analysis using the Python programming language (version 3.10.5) within the integrated development environment (IDE) PyCharm (software version 2022.1.3). This study employed methodology-established principles of social network analysis⁵. I carried out the analysis in two main parts:

Macro-level metrics

Network density: calculated as the ratio of the number of edges to the maximum possible edges between all nodes.

Clustering coefficient: measured the extent to which nodes form clusters by considering the number of edges among neighboring nodes and calculating the average.

Components: identified and counted the number of subgraphs (components) where nodes are mutually connected.

Average path length: evaluated the average “distance” between nodes by calculating the overall average path length in the network⁶.

Micro-level metrics

Degree centrality: measured the importance of each node by counting the number of edges it has in the network.

Closeness centrality: defined as the inverse of the sum of the shortest path lengths from a node to all other nodes, measuring how close each node is to others in the network.

Betweenness centrality: assessed the extent to which a node lies on the shortest paths between other nodes, indicating its importance in information transmission within the network^6,7.

The significance of these macro-level metrics in understanding the structure of scientific collaboration networks and these micro-level centrality measures in scientific collaboration networks has been well documented and used^6,7. Through these analyses, I can identify collaborative relationships and influential researchers in Gastroenterology research. This information may be useful for understanding research trends and planning future collaborative studies.

RESULTS

The co-authorship network of Gastroenterology research from 2000 to 2023 was analyzed using data from the WoS. The analysis was conducted at both macro and micro levels to understand the collaborative patterns and structure within the research community over this period.

2000-2009 network analysis

The network analysis for 2000-2009 revealed a sparse connectivity among researchers (Figure 1), with a network density of 0.00051 (Table 1). This indicates that only 0.052% of all potential collaborative relationships were realized. The network exhibited a high average clustering coefficient of 0.896 (Table 1), suggesting that when collaborations did occur, they tended to form tightly-knit clusters. The network consisted of 1,495 components (Table 1), reflecting a highly fragmented structure where many researchers were isolated or part of small, disconnected groups (Figure 1). The average distance within the network was infinite, indicating that the majority of nodes were not reachable from one another, further emphasizing the network’s fragmented nature⁸.

At the micro level, key researchers were identified based on their centrality measures. The top 20 researchers by degree centrality, which reflects the number of direct collaborations, were led by Gasbarrini, G (0.0098), followed by Niv, Y (0.0086) and Graham, DY (0.008) (Table 2). These researchers had the highest number of co-authorships, positioning them as central figures in the network.

Closeness centrality, which measures how close a researcher is to all other researchers in the network, highlighted Graham, DY (0.085) and Gasbarrini, G (0.085) as having the shortest average distance to other researchers, indicating their strong influence and reach within the network (Table 3). Betweenness centrality, which means the extent to which a researcher acts as a bridge between other researchers, ranked Graham, DY (0.0145) the highest, followed by Gasbarrini, G (0.0107) and Lam, SK (0.0102) (Table 3). These individuals played a crucial role in controlling the flow of information and collaboration within the network.

2010-2019 network analysis

The network analysis for 2010-2019 revealed a significant shift towards a more interconnected co-authorship network (Figure 2). The network density increased to 0.000372 (Table 1), indicating that 0.0372% of possible connections were realized. The average clustering coefficient remained high at 0.904 (Table 1), further suggesting the presence of tightly interconnected clusters of researchers. The number of components was 2,624 (Table 1), indicating a reduction in network fragmentation compared to the earlier period but still reflecting the complexity of the network. The average distance within the network was still infinite, showing that complete network integration had not yet been achieved.

In terms of degree centrality, the top 20 researchers included several prominent figures, with Vandenplas, Yvan (0.0076) leading, followed by Fockens, Paul (0.0074), and Hassan, Cesare (0.0072) (Table 2). Closeness centrality was highest for researchers such as Hassan, Cesare (0.1379), and Vandenplas, Yvan (0.1341), who had better reach across the network (Table 3). The betweenness centrality analysis placed Hassan, Cesare (0.0198) at the top, emphasizing his role as a key connector in the network, followed by Gisbert, Javier P. (0.0149), and Malfertheiner, Peter (0.013) (Table 4).

2020-2023 network analysis

The network analysis for 2000-2023 revealed the collaborative structure in Gastroenterology research as captured by the WoS data (Figure 3). The network density was 0.000381 (Table 1), indicating that 0.0381% of potential collaborative relationships were realized. The average clustering coefficient was calculated at 0.920 (Table 1), reflecting strong clustering behavior among researchers. The network consisted of 2,415 components (Table 1), showing a higher level of fragmentation compared to previous periods. The average distance within the network was infinite, indicating the presence of disconnected components within the network, which contributed to this calculation.

The degree centrality analysis identified key researchers such as Romano, Claudio (0.0071) and Gasbarrini, Antonio (0.0054) as having the most extensive co-authorship networks (Table 2). Closeness centrality was highest for researchers like Nakov, Radislav (0.1345), and Bisschops, Raf (0.1334), signifying their central position within the network (Table 3). Betweenness centrality analysis highlighted the pivotal role of Huang, Ying (0.01) in connecting disparate parts of the network, with Makharia, Govind (0.0096), and Thapar, Nikhil (0.0093) also being significant connectors (Table 4).

Summary

The co-authorship network in Gastroenterology research from 2000 to 2023 evolved from a highly fragmented and sparsely connected structure to a more integrated network, though full integration was not achieved. In the 2000-2009 period, the network had a very low density of 0.00051, reflecting minimal collaboration among researchers. The network consisted of 1,495 components, indicating significant fragmentation and the average distance was infinite, showing the lack of connectivity across many researchers. Key figures like Gasbarrini, G, and Graham, DY emerged as central nodes based on degree and closeness centrality, playing crucial roles in collaboration.

In the 2010-2019 period, the network density increased slightly to 0.000372, and the number of components rose to 2,624, indicating continued fragmentation but with a higher degree of connectivity within clusters. Researchers such as Vandenplas, Yvan, and Hassan, Cesare were identified as key connectors, with Hassan, Cesare having the highest betweenness centrality, indicating his role as a bridge in the network.

The 2020-2023 period saw a further slight increase in network density to 0.000381, with the average clustering coefficient reaching 0.920, reflecting strong clustering behavior. The number of components decreased to 2,415, indicating some consolidation within the network. Key researchers such as Romano, Claudio, and Gasbarrini, Antonio were central to the network, with Huang, Ying, and Makharia, Govind identified as significant connectors based on between­ness centrality.

These results highlight the evolving nature of collaboration in Gastroenterology research, with an increasing number of tight-knit clusters over time but persistent fragmentation across the network. Japanese researchers, including Uchida, K during the 2000-2009 period, and Shimosegawa, Tooru and Sugano, Kentaro and Kinoshita, Yoshikazu during the 2010-2019 period, and Koike, Kazuhiko and Suzuki, Hidekazu and Watanabe, Mamoru during the 2020-2023 period, have emerged as contributors to the research community (TABLES 2 to 4). These demonstrate the substantial contributions of Japanese researchers and research to the development of the field of Gastroenterology.

DISCUSSION

The present study analyzed the co-authorship network in Gastroenterology research, spanning from 2000 to 2023, using data from the WoS. Through this analysis, I aimed to understand the collaborative patterns and identify key researchers and influential groups within this field.

Macro-level insights

The macro-level analysis of the network revealed a low network density (Table 1), indicating that while there is some level of collaboration among researchers, the overall cohesion is limited. The clustering coefficient, however, was moderately high (Table 1), suggesting that certain groups of researchers tend to collaborate closely, forming distinct clusters within the network⁸.

The average path length within the network was found to be relatively short, indicative of a “small-world” structure (Figure 1 to 3). This means that, despite the low density, researchers within the network can reach one another through a limited number of intermediaries. Such a structure facilitates the dissemination of knowledge and may contribute to the rapid spread of innovative ideas and findings within the gastroenterology research community.

Micro-level insights

On a micro-level, the analysis of degree centrality highlighted several key researchers who play pivotal roles within the network due to their high number of collaborations (Table 2). These individuals are likely to be influential in setting research agendas and driving collaborative efforts. Closeness centrality measures revealed researchers who are strategically positioned within the network, with the shortest average distance to others (Table 3), allowing them to effectively disseminate information and maintain a central role in the research community. Betweenness centrality identified researchers who act as critical bridges between different groups, facilitating communication and collaboration across the network (Table 4). These individuals are crucial for maintaining the integrity and connectivity of the research community, as they enable the flow of information between otherwise disconnected groups.

Implications for future research and collaboration

The findings of this study underscore the importance of understanding the structure of collaborative networks in scientific research. In the case of Gastroenterology, the identified key researchers and groups play a significant role in advancing the field. By fostering collaborations and strengthening connections within and between these clusters, there is potential to further enhance the productivity and impact of research in this area. Moreover, the insights gained from this network analysis could be applied to other medical research fields, providing a model for understanding and optimizing collaboration across various disciplines.

Overall, this study contributes to a deeper understanding of the collaborative landscape in Gastroenterology research, offering valuable insights that could inform future research strategies and policies aimed at promoting effective scientific collaboration.

CONCLUSION

The co-authorship network analysis of Gastroenterology research from 2000 to 2023 reveals significant evolution in collaborative patterns over the years. The study identified an initial period (2000-2009) characterized by a highly fragmented network with sparse connectivity, where only 0.052% of potential collaborations were realized. Researchers tended to form tightly-knit clusters, but the network overall was disjointed, with many isolated components and a lack of connectivity across the broader research community.

Moving into the 2010-2019 period, there was a noticeable shift toward increased collaboration, albeit still limited, with 0.0372% of potential connections realized. The network remained fragmented but saw the formation of more cohesive clusters. Key researchers, such as Vandenplas, Yvan, and Hassan, Cesare, emerged as central figures, playing crucial roles in bridging different parts of the network and facilitating information flow.

In the most recent period (2020-2023), the network showed further improvement in connectivity, with a slight increase in network density to 0.0381%. The clustering coefficient reached 0.920, indicating strong clustering behavior among researchers. Despite these improvements, the network still exhibited significant fragmentation, with disconnected components persisting. Researchers like Romano, Claudio, and Gasbarrini, Antonio were identified as central figures in the network, while Huang, Ying and Makharia, Govind served as vital connectors.

Overall, the co-authorship network in Gastroenterology research demonstrates an ongoing trend towards greater collaboration, yet the persistence of fragmentation indicates that full network integration has not been achieved. Japanese researchers have notably contributed to the global Gastroenterology research community, particularly in the later periods, highlighting the importance of continued international collaboration to further advance the field. These findings underscore the need for strategic initiatives to foster more extensive and inclusive collaboration, which could enhance the dissemination and impact of research in Gastroenterology.

REFERENCES

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