Global research trends and hotspots in bronchiectasis: a bibliometric analysis

Introduction

Bronchiectasis is characterized clinically by cough, sputum production, and bronchial infection, as well as radiologically by abnormal and permanent dilation of the bronchi (1-3). Bronchiectasis was previously considered an orphan disease; however, the advent of computed tomography (CT) and pulmonary function tests has significantly improved the understanding of the disease. The pathological mechanism of bronchiectasis is related to abnormal bronchial epithelial remodeling, characterized by a damaged mucociliary structure (1-3). The causes are divided into congenital and secondary. Congenital causes include cystic fibrosis (CF), primary ciliary dyskinesia, primary immunodeficiency, and rare genetic diseases. Secondary causes are mainly related to infection (1-3). Previous studies have shown that the global prevalence of bronchiectasis is gradually increasing (4). Bronchiectasis imposes a significant burden on the global economy (5). A comprehensive understanding of the current research landscape, including emerging trends and key areas of focus, is essential for optimizing patient care and informing future research directions.

Bibliometrics employs statistical techniques and data visualization to reveal the evolution and trends of research fields, offering new insights for the field of medical research (6). Bibliometrics enables retrospective quantitative analysis, facilitates data correlations, and identifies potential areas of research. Bronchiectasis has traditionally been considered a permanent and progressive condition, but some previous studies have shown that bronchiectasis can be reversible if diagnosed and treated promptly in children (7). The improvement of bronchiectasis remains to be explored. Several articles related to bronchiectasis have been published, but a systematic evaluation of the relevant literature has not been conducted yet. The present study aimed to summarize the current status of the bronchiectasis field and identify potential research directions through bibliometric analysis. We present this article in accordance with the BIBLIO reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-528/rc).

Methods

Data source and search strategy

We conducted a subject search of the Web of Science Core Collection (WoSCC) database on June 27, 2025. The search formula was topic search (TS) = (bronchiectas* OR bronchial dila*). A total of 11,589 results were retrieved. The article type was limited to articles. Language was limited to English. The period was limited to 2005–2024. A total of 6,331 articles were exported and stored. The exporting steps were independently completed and verified by two authors, who discussed any discrepancies until a consensus was reached. The literature retrieved from the WoSCC database was exported as “plain text” with the record content as “full record and cited references”.

Data analysis and visualization

Bibliometric methods were applied to analyze research trends, hot topics, and development patterns in bronchiectasis research. This study used R 4.3.2, the Bibliometric.co website (https://bibliometric.com/), and VOSviewer 1.6.20 tools to conduct a visual analysis of the co-occurrence and clustering of keywords, document co-citations, and collaborative relationships among countries and institutions. The screening flow chart is shown in Figure 1. The H-index indicates that a person has at most H papers that have been cited at least H times. This index is a combination of the number of published papers and the number of citations. The H-index can also be used to comprehensively evaluate the impact of journals, indicating the importance of scientists’ contributions (8). To determine China’s contribution to the literature on bronchiectasis, we identified the top-cited studies from Chinese institutions and screened them manually. Articles were classified as “contribution from China” if the first author or the corresponding author was affiliated with a Chinese institution.

Figure 1 Workflow of literature screening and analysis.

Results

Annual average number of publications and analysis of countries and regions

According to the data retrieved from the WoSCC, 6,331 articles related to bronchiectasis were identified from 2005 to 2024. No additional papers were identified. The annual average number of publications has shown an increasing trend, with an average annual growth rate of 11.4%. Figure 2 shows that the number of publications remained relatively stable from 2005 to 2007 but increased from 2008 to 2022.

Figure 2 Annual average number of publications (bibliometric). Changes in the number of publications over the years.

VOSviewer was applied to visualize the number of publications and combine them for analysis of the same countries or regions. The 6,331 articles included in this study were written by people from 127 countries or regions. Figure 3A,3B shows the visualization of the number of publications and collaborations in each country. The node areas in Figure 3A,3B represents the number of publications, and a larger node area corresponds to more publications. Link size refers to cooperation intensity. A total of 58 countries published 10 or more publications. The results showed that the country with the most publications is the United States of America (USA) (n=1,206, 19.05%), followed by China (n=839, 13.25%) and the United Kingdom (UK) (n=626, 9.89%). The countries with the most citations were the USA (42,582 citations) and the UK (33,581 citations). Figure 3A also shows the countries with the most publications in the field of bronchiectasis in recent years, indicating that the USA, China, and the UK have laid the foundation for research on bronchiectasis. Link strength is an indicator used to analyze the strength of the relationship between nodes in VOSviewer, measuring the intensity of cooperation between countries. A higher total link strength corresponds with greater activity. Figure 3A shows the mutual collaboration among different countries. The strongest links were the UK (link strength of 1,200), the USA (link strength of 973), and Italy (link strength of 809), indicating that the UK, the USA, and Italy strongly collaborate in the field of bronchiectasis research.

Figure 3 Analysis of countries engaged in bronchiectasis. (A) Timeline visualization of collaboration among countries in the field of bronchiectasis. The color represents time, with an increase from blue to yellow indicating the passage of time. (B) Density visualization of collaboration among countries in the field of bronchiectasis. The circle size represents publications.

Analysis of the institution collaboration network

A total of 6,735 institutions/affiliates were included in this research, among which 50 institutions/affiliates published more than 40 articles. As shown in Figure 4A,4B, the top three institutions or affiliates, in terms of the number of publications, were the University of Queensland (n=148), the University of Dundee (n=143), and Charles Darwin University (n=105). In terms of the number of citations, Royal Brompton Hospital (7,874 citations) ranked first, followed by the University of Dundee (7,248 citations). The closely cooperating institutions were the University of Queensland and the Charles Darwin University, with total link strengths of 442 and 356, respectively.

Figure 4 Analysis of institutions engaged in bronchiectasis. (A) Visualization map of collaborations between institutions. The lines between nodes represent cooperation between institutions. Each node represents one institution. The size of the node is proportional to the number of documents it contains. (B) Density visualization of collaboration among institutions in the field of bronchiectasis. The size of the node is proportional to the number of publications it has.

Analysis of the journals

The papers identified in this study were published in 1,350 journals, among which 39 journals published 30 or more articles on bronchiectasis. The journal with the most publications was Pediatric Pulmonology (n=142, 2.24%). Table 1 ranks the journals by H-index and lists the specialty journals concerning the bronchiectasis field. The journal with the highest H-index was the European Respiratory Journal, followed by the American Journal of Respiratory and Critical Care Medicine and Chest. Among the journals with the highest number of publications, seven belonged to the Q1 zone, indicating that more articles were published in authoritative journals.

Co-citation reference analysis

A total of 107,516 references were extracted from 6,331 documents, among which 24 references were cited more than 150 times. Among the top-most frequently co-cited references in Table 2, the most cited one was the document entitled “The bronchiectasis severity index. An international derivation and validation study” (9), published in the American Journal of Respiratory and Critical Care Medicine, with a co-citation count of 472. Figure 5 lists the main research contents in chronological order of co-citation documents. The results revealed that before 2002, the field of bronchiectasis was in the initial exploration stage, from case studies of orphan diseases to a summary of the causes of 150 cases of bronchiectasis (10,11). In 2002, a summary of the clinical characteristics of bronchiectasis was proposed (11). During this stage, the research focused primarily on the causes and clinical characteristics of bronchiectasis. Between 2007 and 2014, with the advancement of research on bronchiectasis, scholars began to investigate methods for detecting the condition, including the Bronchiectasis Severity Index (BSI) assessment system. Currently, research on bronchiectasis continues to be refined and expanded (9,12-16). In 2017, the European Respiratory Society first released international guidelines for the management of bronchiectasis (17). The guidelines systematically summarized the causes, treatments, and management of bronchiectasis. With the continuous development of the medical field, the current research focus has gradually shifted to improving the quality of life of patients with bronchiectasis and reducing mortality.

Figure 5 Timeline of the highly co-cited references concerning the bronchiectasis field. ATS, American Thoracic Society; BSI, Bronchiectasis Severity Index; BTS, British Thoracic Society; CF, cystic fibrosis; ERS, European Respiratory Society; IDSA, Infectious Diseases Society of America.

Keyword analysis

Keyword co-occurrence refers to the frequency with which two or more keywords appear in the same document. VOSviewer was used to count the keywords extracted from the 6,331 documents. When the frequency of occurrence was set to 50, a total of 41 keywords reached the threshold. A keyword co-occurrence graph was constructed through VOSviewer (Figure 6). Each node represents a keyword, and the size of the node is positively correlated with the frequency of occurrence. A larger key node corresponds with greater importance in the network structure. The top high-frequency keywords are shown in Figure 6A,6B, sorted by frequency of occurrence: “bronchiectasis”, “cystic fibrosis”, “COPD”, “CT”, “asthma”, “children”, “primary ciliary dyskinesia”, “exacerbation”, “Pseudomonas aeruginosa”, and “interstitial lung disease”. Keywords connected by lines represent co-occurrence frequency, and thick lines represent high co-occurrence frequency. Different colors represent different cluster groups. As shown in Figure 6A, the extracted keywords were primarily classified into five clusters. Cluster 1 (red) and Cluster 2 (green) primarily involved the clinical manifestations, diagnosis, and etiologies of bronchiectasis. Cluster 3 (blue) represents etiologies of bronchiectasis. Cluster 4 (yellow) and Cluster 5 (purple) focus on the differential diagnosis of bronchiectasis and outcomes. The contents of each cluster partially overlap, with a focus primarily on the etiology, evaluation, and manifestations of bronchiectasis.

Figure 6 Keyword co-occurrence of bronchiectasis. Each node represents a keyword, and the size of the node is positively correlated with the frequency of occurrence. A larger key node corresponds with greater importance in the network structure. (A) Clustering diagram of the keyword co-occurrence of bronchiectasis. A different color represents each cluster. (B) Density map of the keyword co-occurrence of bronchiectasis. The yellow keywords represent the highest frequency.

Contribution from China

This study identified the top 10 most influential publications in bronchiectasis research from China, presented chronologically in Table 3. The collection comprises one expert consensus and nine medical research studies. The consensus document, titled “Expert Consensus on the Diagnosis and Treatment of Adult Bronchiectasis in China” (18), was first published in 2012 and received a major update in 2021. The nine research papers focus primarily on key aspects of bronchiectasis in the Chinese population, including disease incidence, etiology (such as post-infective disease, idiopathic, and tuberculosis-related causes), and treatment strategies (encompassing pharmacological interventions and emerging cellular therapies).

Discussion

Research on bronchiectasis is becoming increasingly important in respiratory medicine and has received more attention worldwide. We applied a bibliometric methodology to identify research hotspots and trends in the field of bronchiectasis research. Reviewing the evolution of bronchiectasis research, we can reasonably infer that future trends may develop towards studying the causes of decreased respiratory function.

Research on bronchiectasis has shown an obvious upward trend over the past 20 years, with a total of 6,331 articles published. The number of publications in the initial exploration stage was relatively small. After 2005, the overall number of publications steadily increased, indicating good progress in this field, as previously highlighted by a bibliometric study on bronchiectasis in children (19). Among the top 10 countries in terms of the number of publications, most are in Europe and North America, particularly the USA and the UK. Moreover, close cooperation can be observed among countries. The strength of cooperation links is most significant among the UK, the USA, and Italy, indicating that these countries are more active in this field. International cooperation needs to be strengthened to promote exchanges and win-win situations in this field.

China ranks second in terms of the number of publications. However, since 2014, the number of publications in China has increased, with 114 articles published in 2023 alone, ranking first among its peers. There is evidence of increasing research activity from China and potential for greater impact with enhanced international collaboration and focus on high-impact topics (19). China has achieved significant progress in bronchiectasis research in recent years. The 2021 update of the “Expert Consensus on the Diagnosis and Treatment of Adult Bronchiectasis in China” reflects a major shift in clinical strategy, from primarily managing acute exacerbations toward emphasizing long-term, standardized, and individualized care during stable phases, with greater focus on etiological screening, disease severity assessment, and implementing chronic disease management models (18). Epidemiological studies indicate a rapid increase in both the prevalence and disease burden of bronchiectasis in China (20). Research has identified distinctive clinical features: post-infective disease (43.2%) and idiopathic (29.6%) are the most common causes, Pseudomonas aeruginosa (20.8%) is the most prevalent pathogen, and patients in low-income regions experience a higher disease burden (21,22). Regarding exacerbations, studies show viral infections often correlate with upper respiratory symptoms, while new bacteria lead to more severe lower respiratory symptoms and elevated inflammation; bacterial-viral co-infections are associated with broader symptoms and greater inflammatory burden (23,24). Therapeutic approaches have formed a complete system from drug to cellular level: drug therapies cover strategies from mucoactive agents (such as N-acetylcysteine) to inhaled antibiotics (such as tobramycin solution), and multiple randomized controlled trials have confirmed that it can effectively reduce acute exacerbations and improve quality of life (25,26). Meanwhile, at the level of cell and regenerative medicine, the repair mechanism of lung progenitor cells (such as P63⁺ cells) is explored (4). The latest clinical trials have shown that autologous lung progenitor cell transplantation can significantly reduce the damaged area of the lungs, offering a promising therapeutic approach for bronchiectasis. This transition from macro-level drug interventions to micro-level cellular therapy highlights both the remarkable progress and expanding depth of bronchiectasis research in China.

The top three journals in terms of H-index are the European Respiratory Journal, the American Journal of Respiratory and Critical Care Medicine, and Chest. These three journals have high academic output and academic influence in this field. Clinicians or researchers interested in the field of bronchiectasis can focus on the above three journals.

The highly co-cited articles were published relatively early, including three guidelines or statements issued by medical associations, one article on imaging examinations, two evaluation systems, and four articles summarizing the pathophysiology, etiology, clinical manifestations, diagnosis, treatment, and prognosis of bronchiectasis. The most cited article was “The bronchiectasis severity index. An international derivation and validation study”, published by Chalmers JD, in the American Journal of Respiratory and Critical Care Medicine in 2014 (9). This research was the first multicenter international study to describe a clinical prediction tool for bronchiectasis. Another is the “European Respiratory Society guidelines for the management of adult bronchiectasis” (17), published in the European Respiratory Journal in 2017.

Keywords represent the main research topics. Co-occurrence and clustering analyses were conducted based on keywords, and five clusters were ultimately obtained. A certain overlap is found in the contents of the clusters. The time overlay diagram highlights the research hotspots in the field. Of course, bronchiectasis is the central and most important keyword. The early evaluation of bronchiectasis primarily focused on its clinical manifestations, evaluation, and treatment. The current research hotspots primarily focus on the causes of decreased respiratory function. The early research on bronchiectasis is closely related to asthma, chronic obstructive pulmonary disease (COPD), CF, and CT. Bronchiectasis is one of the most common asthma-associated comorbidities, which can increase airway inflammation and exacerbation rates, ultimately leading to respiratory dysfunction (27,28). Bronchiectasis and COPD have overlapping clinical features, often leading to a concurrent diagnosis (29). Studies have shown that COPD and asthma patients with bronchiectasis have more obvious respiratory symptoms, more significant lung function damage, and a worse prognosis (30). CF, the most common autosomal recessive genetic disease in Caucasians, is one of the congenital factors that induce bronchiectasis. CF was identified as a cluster keyword in Cluster 2. CF is the most common cause of bronchiectasis in Caucasians (31), and research on CF often implies research on bronchiectasis. CT imaging remains the preferred imaging method for diagnosing bronchiectasis, with high-resolution computed tomography (HRCT) being more sensitive and specific for diagnosis. Infection and inflammation are associated with bronchiectasis and can lead to acute bronchiectasis (32), which are significant factors contributing to a decline in respiratory function. Bronchiectasis is not uncommon in Asians, but even after a comprehensive examination, the cause of bronchiectasis in most patients cannot be determined (18). But a recent prospective observational cohort study (BE-China) revealed significant differences between Chinese bronchiectasis patients and their European and Indian counterparts in terms of etiology, disease severity, pathogen distribution, and treatment patterns. Among Chinese patients with bronchiectasis, the most common etiology was infection (43.2%), followed by idiopathic causes (29.6%), with tuberculosis also being relatively common (12.2%) (22). “Children” was also identified as a key term. It was not identified in a previous bibliometric analysis of bronchiectasis because it only included papers on pediatric populations (19), while the present study included all papers on bronchiectasis, irrespective of the population or etiology. Nevertheless, bronchiectasis is a common condition in children that results from repeated or severe lung infections such as pneumonia, tuberculosis, or whooping cough. Other causes include immune deficiencies, blockages (e.g., inhaled foreign objects), congenital lung abnormalities, CF, primary ciliary dyskinesia, aspiration of stomach acid, and neurological issues affecting swallowing (3,32,33). Exploring the cause remains a research hotspot. It is also the main difficulty and challenge faced in clinical practice. We can pay attention to this type of research and continue to dig deeper into it to guide research and clinical practice.

This research used bibliometrics and VOSviewer to analyze and visualize the development trends and research hotspots in the field of bronchiectasis based on the WoSCC. However, this study has several limitations. Firstly, considering that the articles on bronchiectasis research included in WoSCC have been published since 1975, this may be because documents published earlier have not been analyzed since this study began in 2005. Secondly, different bibliometric analysis software packages employ varying calculation methods, which may introduce bias in the analysis results for the same data. Thirdly, only WoSCC was used for the search. WoSCC offers a broader literature coverage than PubMed. Compared with PubMed, WoSCC also offers a more comprehensive citation indexing, curated content, historical depth and coverage, and more advanced analytical tools. Nevertheless, we agree that using multiple databases could ensure that we identify all available studies. We performed a similar search on PubMed. The PubMed search identified a slightly smaller number of papers.

Conclusions

Bronchiectasis studies are rapidly increasing in number, and the USA, China, and the UK are becoming increasingly active and emerging as world leaders in this field. The causes of decreased respiratory function might be the focus of subsequent research and the direction of development. This study also provides directions and references for future research by medical professionals.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the BIBLIO reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-528/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-528/prf

Funding: This study was funded by the Science and Technology Development Fund, Macau SAR (Nos. 0098/2021/A2 and 0048/2023/AFJ), and the Chinese Medicine Guangdong Laboratory (No. HQCML-C-2024007).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-528/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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