Global trends and hotspots in research of cough variant asthma: a bibliometric and visual analysis from 2004 to 2024

Introduction

Cough variant asthma (CVA) is recognized as a unique asthma phenotype, mainly presenting with persistent cough as its defining symptom. It is a peripheral airway inflammatory disease similar to asthma (1). With the increasing environmental pollution, the incidence of CVA has been rising. A large-scale, multi-center epidemiological study in China showed that CVA is the most common cause of chronic cough. Among adults with chronic cough in China, approximately 14–27% are diagnosed with CVA (2). Unlike typical asthma, CVA is not associated with significant shortness of breath or wheezing. Patients mainly present with persistent, irritating dry cough, which is often triggered or aggravated by upper respiratory infections, intense physical exercise, or exposure to allergens. Owing to its presentation, CVA is frequently underrecognized in practice and can be mistaken for alternative bronchial pathologies. Failure to manage the condition adequately may increase the risk of transition to conventional asthma (3). The pathogenesis of CVA is similar to that of asthma, involving airway inflammation, hyperresponsiveness, and airway remodeling (4). Both environmental and genetic factors play crucial roles, with neurogenic mechanisms and various cells contributing to immunoglobulin E (IgE)-mediated hypersensitivity and chronic airway inflammation. Despite growing attention from researchers, bibliometric studies in the field of CVA remain limited. A bibliometric review can provide a quantitative summary of the global research trends, influential contributors, and emerging topics. Thus, this study aimed to explore the development trajectory and research hotspots of CVA using multiple visualization tools.

Bibliometric research refers to the analysis of key information from published articles within a specific research field to outline its developmental trajectory, identify research hotspots and characteristics, and predict future trends (5). Bibliometric analysis typically presents its findings through visualization, which results in structured, interconnected, and pattern-rich maps. These maps intuitively display the complex relationships between different research topics, providing insights into the field’s development and progress (6). Currently, various software tools are available for bibliometric visualization, among which VOSviewer and CiteSpace are the most widely used and representative analysis tools.

Analyses and visualization of the CVA research domain were carried out using the bibliometric tools CiteSpace 6.1.R3 and VOSviewer 1.6.18. The map provides an intuitive overview of the current research status, hotspots, and trends in this area, offering valuable insights for further research. We present this article in accordance with the BIBLIO reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-920/rc).

Methods

Literature collection and selection strategy

Relevant publications were collected from the Web of Science (WOS) Core Database, with literature extraction completed by January 1, 2025, to avoid potential biases due to database updates. The search strategy was: ((TS=(Cough variant asthma)) OR TS=(Cough-variant Asthma)) OR TS=(Cough Variant Asthma Cva). The search was restricted to English-language articles published between January 1, 2004, and December 31, 2024, excluding meeting abstracts, letters, and other types of publications.

Bibliometric analysis

The dataset from the WoS Core Collection was exported in plain text format with complete records and references (download_xxx.txt). CiteSpace 6.1.R3 was applied to conduct deduplication and to analyze dynamic indicators, including keyword bursts, timeline evolution, and co-citation bursts. VOSviewer 1.6.18 was employed to explore collaborative structures across authors, institutions, and countries, as well as to map keyword co-occurrence and citation relationships involving references, journals, and authors.

No quality assessment of the included publications was conducted, as this study did not involve a systematic review of evidence-based outcomes. The study assessed several metrics, including the number of publications, citation frequency, H-index, average citation impact, and the overall strength of links, which indicate the intensity of collaboration or co-occurrence.

Statistical analysis

Descriptive statistics were applied to evaluate the number of publications, citation frequency, H-index, and average citations per article. Network indicators such as total link strength were used to assess the intensity of collaboration and co-occurrence. CiteSpace 6.1.R3 and VOSviewer software were employed for visualization and network analysis, including co-authorship, co-citation, and keyword co-occurrence mapping. Burst detection and timeline analysis were also performed to identify emerging research trends and hotspots.

Results

Annual publication

Excluding meeting abstracts, letters, and other types of publications, and after deduplication, this study included a total of 366 articles and 58 reviews.

Figure 1A shows the trend of annual publication and citation counts from 2004 to 2024. From 2004 to 2024, the annual publication and citation counts for CVA generally increased, but with different rates of growth and fluctuations. The number of publications remained relatively stable between 2004 and 2015, averaging around 10 to 20 articles per year. From 2016 onwards, there was a significant rise, peaking at nearly 30 articles in 2019, and maintaining a high level (around 30 to 35 articles) from 2020 to 2024. Citation counts showed a more pronounced increase. They remained low between 2004 and 2013, then rapidly climbed after 2014, reaching a peak between 2019 and 2023, with citations nearing 900 in 2022. Although there was a slight decline in 2024, citation numbers remain high. This trend indicates a significant increase in academic activity and influence in the CVA research field in recent years, especially after 2014, with a notable rise in citation rates of research findings. Figure 1B presents the top ten countries/regions in terms of publication output over the last two decades, showing that Japan led the field prior to 2015. However, after 2015, China rapidly increased its publication output, surpassing Japan to become the leading country, a position it has maintained to the present year.

Figure 1 Global publication trends and leading contributors in CVA research [2004–2024]. (A) Annual publication and citation trends in CVA from 2004 through 2024. (B) Yearly publication trends in the top 10 contributing countries/regions for CVA between 2004 and 2024. CVA, cough variant asthma.

Distribution of countries/regions and institutions

Over a twenty-year period, a total of 53 countries/regions have been engaged in CVA research, forming a global collaborative network (Figure 2). Table 1 lists the top 10 countries by publication volume. Among these, China ranked first with the highest number of publications (169, accounting for 39.86%), 2,113 total citations, an average of 12.50 citations per paper, an H-index of 20, and a total link strength of 41. Despite its high publication output, China’s international collaborations, as reflected by its total link strength, remain relatively limited, highlighting the need for enhanced cooperation with other countries and regions. The UK ranked second in publication output, contributing 41 articles (9.67%) with a total of 2,014 citations, an average of 49.12 citations per paper, an H-index of 19, and the highest cumulative link strength of 52. The UK’s robust collaboration network is evident through its close connections with the US, China, and other European countries. As the third-most productive country, the US produced 50 publications (11.79%), amassing 1,878 citations, with an average citation rate of 37.56 per article, an H-index of 17, and a total link strength of 48. The US serves as a central hub in the global collaboration network, closely connected with numerous countries, especially the UK and Japan. With 96 publications (22.64%), Japan accumulated 1,742 citations, averaging 18.15 citations per paper, holding an H-index of 26, and a total link strength of 32, reflecting a balanced contribution in both productivity and academic impact. Japan’s collaborations are notably strong within the Asian region, particularly with South Korea and China. Other notable contributors include Canada (13 publications, 3.07%) with the highest average citations per paper (84.08), Italy (18 publications, 4.25%) with 758 total citations, and the Netherlands (8 publications, 1.89%) with 727 total citations and the second-highest average citations per paper (90.88). While these countries have lower publication volumes, they have produced high-quality research that is widely cited within the academic community. From Figure 2, it is clear that the global collaboration network is dominated by key players such as the US, China, the UK, and Japan. However, countries like China, despite their high output, have relatively sparse international connections, suggesting the need for greater global engagement.

Figure 2 Visualization of the national and regional collaboration network in the field of CVA. (A) The figure was generated using the Bibliometric Online Analysis Platform. (B) Node size corresponds to the number of publications per country/region, while warmer colors indicate more recent outputs. Lines connecting nodes represent collaborative relationships, with thicker lines denoting stronger cooperation. (C) The map shows the geographic distribution of research collaboration among countries/regions in CVA. Circle size reflects publication count, circle color denotes cluster affiliation, and line thickness indicates collaboration strength. CVA, cough variant asthma.

A total of 667 different research institutions have contributed to CVA research publications. Figure 3 illustrates the collaboration network among institutions with at least 3 publications, while Table 2 lists those with at least 7 publications. The top five institutions by publication count were: Guangzhou Medical University, Kyoto University, Kanazawa University, Shanghai Jiao Tong University, and Tongji University. Notably, Guangzhou Medical University had the highest publication count and average citation rate, highlighting its significant academic influence in the field. Kyoto University ranked first in the H-index, reflecting its long-standing academic contributions.

Figure 3 Knowledge map of institutional collaborative network related to CVA. The size of the nodes represents the number of publications from each institution. Warmer colors indicate more recent publications. Connections between nodes indicate inter-institutional collaboration, where thicker lines denote stronger links. CVA, cough variant asthma.

Furthermore, half of the top 10 institutions in terms of publication count were from China, with Japan also making substantial contributions. This suggests that Chinese institutions have played a key role in advancing CVA research. However, some institutions, such as Kanazawa University and Nagoya City University, have relatively low total link strength, indicating a need for stronger international collaboration and broader dissemination of their research.

Analysis of journals and cited journals

In the field of CVA research, a total of 175 journals have contributed to related publications. The top 10 journals with the highest number of publications are listed in Table 3. The Journal of Asthma (US) ranked first, with 22 publications (5.19%), an average citation per article of 14.18, an H-index of 11, an impact factor (IF) of 1.7 (Q3), and a total link strength of 127. It was followed by Pulmonary Pharmacology & Therapeutics (UK) with 16 publications (3.78%), an average citation per article of 20.13, an H-index of 12, an IF of 3.3 (Q2), and a total link strength of 136. In third place, Respirology (Australia) published 13 articles (3.07%), with an average citation per article of 21.00, an H-index of 9, an IF of 6.6 (Q1), and a total link strength of 139. Notably, Chest (US) achieved the highest average citation per article (68.67) and the highest citation count [824], underscoring its status as a core journal in the field.

Among the top 10 journals, 50% are classified as Q1, reflecting the high quality of research in this domain. Geographically, 30% of the journals are based in the US, with the remaining contributions distributed across the UK, Australia, Japan, Germany, China, and Ireland. This suggests that journals from the US and the UK play a leading role in the dissemination of CVA-related research. Additionally, Journal of Thoracic Disease (China) and Evidence-Based Complementary and Alternative Medicine (UK) had relatively lower average citation counts and total link strengths, indicating potential for further enhancement in international collaboration and citation impact.

In the field of CVA research, the journal co-citation network (Figure 4) identifies journals with significant academic influence, as reflected by their citation counts and total link strengths. Table 4 lists the top 10 most co-cited journals in this field. Among them, Chest (US) ranked first. This was followed by American Journal of Respiratory and Critical Care Medicine (US). The third was European Respiratory Journal (UK). Notably, with an IF of 96.3, the New England Journal of Medicine (US) led all journals in this metric. The analysis also highlights strong co-citation relationships among these journals. For instance, Chest and European Respiratory Journal frequently co-occur with Journal of Allergy and Clinical Immunology, Thorax, and American Journal of Respiratory and Critical Care Medicine, demonstrating their central roles in the dissemination of CVA-related research. Additionally, journals like Respirology (Australia) and Pulmonary Pharmacology & Therapeutics (UK), although lower in citation counts, maintain relevance through their consistent contributions and interdisciplinary appeal. Among the top 10 journals, 80% belonged to Q1, reflecting the high quality of research cited in this field. Geographically, 50% of these journals originated from the US, 40% from the UK, and the rest from Australia, demonstrating the significant contributions of American and British journals in advancing CVA research. With an average IF of 22.1 and an average H-index of 5.7, this analysis emphasizes the importance of high-quality journals in shaping the CVA knowledge base. Researchers are encouraged to prioritize these leading journals for a deeper understanding of the field.

Figure 4 The co-citation network map of journals related to CVA. Circle size corresponds to each journal’s publication output, and links between circles illustrate collaboration strength, with thicker lines denoting closer connections. Distinct colors indicate different clusters. CVA, cough variant asthma.

Authorship and co-citation network analysis

A total of 2,037 authors have contributed to research in the field of CVA. The knowledge map of author collaboration, shown in Figure 5A, illustrates the relationships among authors with more than three publications. Table 5 lists the top 9 authors by publication count, with the top five being Akio Niimi, Masaki Fujimura, Kefang Lai, Noriyuki Ohkura, and Hisako Matsumoto. These authors have made significant contributions to the field, with Niimi A, being the most prolific, contributing the most publications in CVA research. His recent review systematically summarized the clinical and physiological features of CVA, its prognosis, and determinants, and offered expert opinions on treatment duration. He suggests that patients with risk factors for recurrence and/or chronic airflow obstruction/remodeling should receive long-term treatment (7). Lai K, with the highest citation count, demonstrates the wide recognition of his work. His most recent nationwide cross-sectional study of 11,718 patients identified independent factors for severe cough, such as female gender, asthma, chronic cough, gastroesophageal reflux, coronary heart disease, diabetes, and coronavirus disease 2019 (COVID-19) vaccination history (8). Furthermore, Michiaki Mishima, the author with the highest H-index in the field, shares Lai’s view that gastroesophageal dysmotility is an independent predictor of quality of life in CVA patients (9). Regarding publication volume, nine authors have published more than 9 papers, with seven of them from Japan, underscoring Japan’s significant contribution to CVA research and the important role of these authors in the field.

Figure 5 Network visualization of author collaboration and co-cited authors in CVA research. (A) Collaboration network of authors. Node size corresponds to the number of publications by each author. Warmer-colored nodes indicate more recent average publication years. Connecting lines denote cooperative relationships among authors, with thicker lines suggesting stronger collaboration. (B) Co-cited author network. Node size reflects the frequency of citations. Distinct colors indicate different clusters, while the connections and line thickness represent the presence and strength of co-citation relationships. CVA, cough variant asthma.

The author’s co-citation network knowledge map (Figure 5B) displays authors with at least 20 citations. Co-citation represents the joint citation of authors within a paper, providing insight into the field’s scholarly network and identifying leading research teams. In the CVA field, Table 6 lists the top 10 authors with the highest co-citation counts, the top five most co-cited authors are: Irwin RS (381 citations, total link strength 8,470, H-index 55, US), Niimi A (362 citations, total link strength 7,418, H-index 46, Japan), Fujimura M (353 citations, total link strength 7,404, H-index 37, Japan), Morice AH (256 citations, total link strength 6,608, H-index 10, England), and Brightling CE (204 citations, total link strength 5,568, H-index 48, England). Irwin RS, as the most frequently cited author, recently published a study indicating that due to the differences in respiratory physiology and anatomical structures between children and adults, the physiological mechanisms in children result in different physiological functions, drug metabolism, and drug responses. Therefore, the diagnosis of cough hypersensitivity syndrome is inappropriate for children (10). Niimi A, ranked second, also has a high citation count and H-index. Among the top 10 most co-cited authors, three are from the US, three from the UK, two from Australia, and two from Japan, which suggests that high-quality research in this field primarily originates from developed countries. However, the research contributions from other countries remain relatively limited, likely due to insufficient research funding, inadequate research infrastructure, or insufficient international collaboration. To promote the global development of this field, it is essential to strengthen international cooperation, facilitate the sharing of knowledge and resources, and encourage developing countries to invest more in research to improve their research capacity.

In our analysis of authors, we found that the top 10 authors by publication count in the CVA field all come from Asia (Japan, China, South Korea), indicating that Asia is becoming a central hub for CVA research. This phenomenon can likely be explained by several factors: CVA appears to have a higher prevalence in Asia, which may be driven by genetic factors, environmental influences (such as air pollution), and increased clinical awareness. Additionally, some researchers(Niimi A, Fujimura M, Lai K) in Asia have played a pioneering role in the field, establishing foundational work and building robust research teams that continue to produce high-quality publications. Several Asian countries also place significant emphasis on respiratory disease research, providing both funding and policy support.

It is worth noting that this study includes only English-language publications, and Asian scholars have increasingly published in English in international journals, which has further increased their visibility in our analysis. However, in the co-cited author analysis, we found that only three of the top 10 co-cited authors are from Asia, suggesting that while Asia leads in publication volume, Western scholars still significantly influence the theoretical and foundational literature in CVA research.

This pattern of “Asia leading research and the West providing theoretical foundations” reflects the global collaboration and development trends in CVA research.

Analysis of cited references

References appearing together in at least 20 citations are displayed in the co-citation network knowledge map. Reference co-citation represents the joint citation of multiple references in a research work. Examining the key nodes in the co-citation network provides insight into the field’s intellectual structure, highlights foundational studies and emerging research trends, and identifies influential publications that have shaped its development (11).

Table 7 lists the 10 most cited papers in the field of CVA. The average IF of the journals in which these papers were published (excluding one discontinued journal) is 31.28, with an H-index of 349.56, and all are Q1 articles, indicating their exceptionally high academic quality and their foundational role in CVA research over the past two decades. The top-ranked paper is by Corrao, published in 1979, which first introduced the concept of “cough variant asthma”. This type of patient presents with airway hyperresponsiveness, inducible diffuse airway constriction, and a good response to bronchodilator treatment, with the sole symptom being “cough”. This discovery significantly raised clinicians’ awareness of the potential for asthma in patients with isolated cough (12). The second most cited paper is a clinical retrospective study by Fujimura M, published in 2003. Through a comparative analysis of 82 atopic cough patients and 55 CVA patients, the study found that CVA may be a precursor to atopic cough, though atopic cough does not always manifest as CVA. The study recommends early use of inhaled corticosteroids to prevent the progression from CVA to atopic cough (13). The third most cited article, authored by Niimi A and a team, focuses on the role of eosinophils in CVA. The study compared CVA patients, typical asthma patients, and healthy controls, finding no significant difference in the levels of eosinophils between CVA and typical asthma patients. Moreover, the severity of both conditions was closely linked to eosinophil levels. This finding further underscores the importance of anti-inflammatory treatment for CVA patients (14). The fourth most cited paper was also authored by Niimi A and colleagues. The study, through bronchial biopsies, found that the subepithelial thickness in CVA patients was 7.1 microns, compared to 8.6 microns in typical asthma patients and 5.0 microns in healthy controls. This finding provides strong evidence for early anti-inflammatory treatment in CVA patients (15). The fifth paper, led by Kohno S, is the “Japanese Respiratory Society Cough Treatment Guidelines”. The guidelines offer a detailed classification of cough, defining acute, subacute, and chronic cough periods, and adapting Western research to the clinical context in Japan, providing more practical recommendations for the diagnosis and treatment of cough (16). The sixth paper, authored by Irwin RS in 1990, is a validation study that prospectively evaluated chronic cough patients and a normal control group. The study confirmed that an evaluation protocol for chronic cough patients remained clinically applicable, laying the foundation for future clinical practice (17). The seventh paper, led by Fujimura M, is a prospective multicenter study on the causes of chronic cough in Japan. The study found that atopic cough, CVA, and cough-dominant asthma were the major causes of chronic cough in Japan, providing an important contribution to the disease spectrum of chronic cough in the country (18). The eighth most cited paper, published by Brightling in 1999, highlighted that eosinophilic bronchitis is one of the most common causes of chronic cough. The study emphasized the importance of correctly identifying this condition for clinicians and recommended airway inflammation assessment to optimize treatment for such patients (19). The ninth paper, authored by Lai K and colleagues from China, analyzed the causes of chronic cough in a prospective multicenter study in China. The research identified CVA, upper airway cough syndrome, eosinophilic bronchitis, and atopic cough as common causes of chronic cough in China, enriching the understanding of the disease spectrum in chronic cough within the country (2). The tenth paper, by Irwin RS, focused on a study of CVA, employing a prospective, randomized, double-blind, cross-over design. The study concluded that a positive methacholine challenge test alone is insufficient to diagnose asthma; CVA can only be definitively diagnosed when there is a clear improvement in cough symptoms with Bronchodilator (20).

References with citation bursts

Citation bursts refer to a sudden increase in the citation frequency of a paper over a short period. Analyzing citation bursts helps identify research hotspots and emerging trends within a field (21). By setting the shortest duration of a burst to 3 years, the top 30 references with the most significant citation bursts were detected (Figure 6). The light blue bars represent the timeline, while the dark blue bars indicate the period after the paper’s publication. The red bars denote the period from the onset to the conclusion of the citation burst. The “strength” indicates the intensity of the burst, with higher values reflecting a stronger burst (22).

Figure 6 The 30 references exhibiting the most pronounced citation bursts. The blue line represents the overall time span, while the red line indicates the duration of each citation burst.

Among these 30 references, five articles exhibited citation bursts continuing into 2024, highlighting emerging trends in CVA research and meriting further investigation. The first of these is a guideline published by Morice AH in 2020 (23), which integrates the latest advancements in the pathophysiology, diagnosis, and treatment of chronic cough. The guideline defines the scope of cough hypersensitivity syndrome and outlines the treatment characteristics of CVA, with a particular emphasis on the challenges in diagnosing cough in children. Additionally, it highlights key research directions in the field of cough, including observational cohort studies on chronic cough, the development of assessment tools, and the identification of practical biomarkers. The second paper, authored by an international expert group from the Global Initiative for Asthma (GINA) association, reviewed recent scientific literature and incorporated new evidence regarding asthma (24). Published on World Asthma Day, May 3, 2022, the update focused on asthma management during the COVID-19 pandemic, diagnostic processes, management pathways, and the decision tree for severe asthma, providing important guidance for asthma management. The third paper, authored by Uryasjev in 2020, provides a comprehensive review of the evolution of CVA terminology, its pathophysiological mechanisms, biomarkers, and diagnostic criteria (25). It emphasizes the importance of considering CVA as a potential diagnosis in patients with chronic cough. The fourth article investigates the diagnostic value of fractional exhaled nitric oxide (FeNO) and small airway functional parameters in pediatric CVA (26). Through a controlled trial, the study found that the combination of FeNO and maximum mid-expiratory flow/maximum expiratory flow at 50% offers high sensitivity and specificity for diagnosing CVA. The fifth study focuses on small airway conditions in CVA patients, revealing that over 50% of CVA patients have small airway disease (27). Moreover, the study indicates that demographic and clinical features, as well as airway eosinophils and drug responses, are not specific to CVA. However, the expiratory flow at 50% stands out as a simple and feasible marker for identifying CVA.

Analysis of keywords

A paper’s keywords capture its core content and summarize the main research themes. Analyzing keywords helps capture the research hotspots and emerging trends within a given field (28-30). The keyword co-occurrence network, shown in Figure 7, illustrates keywords that appeared at least 10 times. Table 8 lists the 40 most frequent keywords. High-frequency keyword analysis reveals that “cough variant asthma”, “asthma”, “chronic cough”, “variant asthma”, “cough”, “airway inflammation”, “inflammation”, “diagnosis”, “management”, and “atopic cough” are the primary research themes.

Figure 7 The knowledge map of the keyword co-occurrence network related to CVA illustrates the relationships between keywords based on their co-occurrence patterns. The size of the nodes corresponds to the frequency of keyword occurrences, with larger nodes representing more frequent keywords. Node coloration shows average appearance time, with warmer tones for more recent occurrences. Node links represent co-occurrence patterns and their strengths, and the visualization was generated with VOSviewer. CVA, cough variant asthma.

The keyword timeline map reveals nine clusters, with keywords from the same cluster positioned along the same timeline. The timeline is placed at the top, with more recent keywords appearing further to the right (Figure 8). The clustering metrics, Q =0.3961 (>0.3) and S =0.7746 (>0.7), indicate that the partition structure is significant and the clustering is both compelling and effective (31). The inter-axis map clearly shows the number of keywords within each cluster. A cluster with a higher number of keywords generally reflects a more influential research domain. Additionally, the map provides insights into the time span of the keywords in each cluster, as well as the rise, peak, and decline of research within specific clusters, further exploring the temporal characteristics of the fields represented. The analysis of the keyword timeline map indicates that “cough variant asthma”, “airway inflammation”, “management”, and “methacholine” constitute the main areas of ongoing investigation.

Figure 8 Timeline knowledge map of keywords related to CVA, the keywords of the same cluster are placed on the same horizontal line, and the further to the right, the later they appear. CVA, cough variant asthma.

Keyword bursts, defined as rapid surges in keyword frequency, can be analyzed to detect emerging topics and main areas of research activity (32,33). With a shortest burst period of three years, the analysis highlighted the 15 keywords with the strongest surge in citations (Figure 9). Among them, one keyword’s citation burst ended in 2024. Therefore, the “chest guideline” represents the current research trend in the field.

Figure 9 The 15 keywords showing the most prominent citation bursts. The blue segments represent the full time span under analysis, while the red segments highlight the specific periods during which citation bursts occurred.

Overall, the keyword analysis highlights that research in the CVA field is shifting from basic clinical characterization (e.g., “cough”, “asthma”) to more specific diagnostic markers (e.g., “exhaled nitric oxide”, “FeNO”) and treatment strategies (e.g., “management”, “guidelines”), with pediatric CVA becoming a new research frontier.

Discussion

Research output and global distribution

This bibliometric study summarizes two decades of research on CVA. Since 2014, both publications and citations have risen markedly, reflecting growing recognition of CVA. China has become the most productive country, surpassing Japan after 2015, but its international collaboration remains limited. In contrast, the US and the UK occupy central positions in the global network, supported by strong partnerships, while Japan continues to exert significant influence in Asia. At the institutional level, Guangzhou Medical University and Kyoto University are among the most active contributors. The increasing presence of Chinese universities highlights the region’s expanding role, though some institutions show weak external connections. Broader collaboration will be important to enhance global visibility.

Journals, authors, and influential references

The Journal of Asthma, Pulmonary Pharmacology & Therapeutics, and Respirology are key outlets for CVA studies, while Chest and the American Journal of Respiratory and Critical Care Medicine dominate in co-citations, confirming their central role in shaping the field. Most highly cited journals are Q1, and their concentration in the US and the UK underscores their dominance in agenda setting. Leading authors such as Niimi A, Fujimura M, and Lai K have contributed extensively, from defining clinical features to large-scale epidemiological surveys (2,13-15,18). Most prolific authors are based in Asia, but Western researchers remain highly influential in co-citations, providing much of the theoretical framework. This pattern suggests a complementary trend: Asia driving output, while the West anchors foundational theory. The most cited references include the initial description of CVA and subsequent clinical studies linking airway inflammation to disease mechanisms. Guideline papers also rank prominently, reflecting their role in standardizing diagnosis and management.

Emerging research frontiers

Recent citation bursts highlight evolving priorities. The 2020 chronic cough guideline and updated GINA reports integrate CVA into broader respiratory care, particularly in children (23,24). Research on biomarkers such as FeNO and small airway function is expanding, aiming to improve diagnostic precision (27). Keyword trends support this shift, moving from general terms (“asthma”, “cough”) toward diagnostic markers, treatment strategies, and pediatric CVA. The prominence of “guidelines” and “FeNO” indicates a growing emphasis on evidence-based practice and non-invasive testing.

Strengths, limitations, and future directions

This is the first comprehensive bibliometric mapping of CVA research. By combining productivity, impact, and collaboration metrics, it highlights both achievements and gaps. Although the WOS is one of the most widely used databases for bibliometric analysis (34,35), its reliance on English-language publications may have excluded relevant studies, and bibliometric approaches often emphasize quantity rather than depth.

Despite these limitations, the findings show that CVA research is expanding rapidly, with Asia contributing most of the output and Western countries shaping much of the theoretical base. Future work should strengthen international collaboration, focus on pediatric populations, validate biomarkers, and refine guidelines to better integrate research into clinical practice.

Conclusions

We conducted bibliometric and visualization analysis of CVA-related research published over the past two decades in the WOS core collection database using VOSviewer, CiteSpace, and the Bibliometric Online Analysis Platform. Our findings indicate that China has published the most articles, while Japan stands out as the most influential country in this field. Guangzhou Medical University is the most prolific institution, with 25 publications. The Journal of Asthma is the journal with the highest number of publications, while Chest is the most cited journal. Niimi A has published the most articles and holds the highest H-index, while Irwin RS is the most cited author and has the highest citation-based H-index. Both researchers have significant academic influence in the CVA field. Key research topics include “cough variant asthma”, “asthma”, “cough”, “diagnosis”, “management”, “eosinophilic bronchitis”, “children”, “exhaled nitric oxide”, “prevalence”, and “bronchoconstriction”, with the Chest guideline emerging as a key trend in the field.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the BIBLIO reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-920/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-920/prf

Funding: This work was supported by the Launch Fund for PhD Startup Fund at The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine [grant No. GYZYYFY-BS-2024(03), to H.Y.Y.].

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-920/coif). H.Y.Y. received financial support for this research from the Launch Fund for PhD Startup Fund at The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine [grant No. GYZYYFY-BS-2024(03), to H.Y.Y.]. The other 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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