Carotid artery stenosis, or carotid stenosis (CS), is responsible for 8–12% of all ischemic stroke cases. Indeed, CS is an important preventable cause of ischemic stroke (1). Close monitoring and intervention are recommended for patients with moderate and severe (50–99%) CS and symptomatic CS (such as transient ischemic attacks) (2). Advances in treatment modalities, including carotid artery angioplasty/stenting (CAS) have helped diversify treatment options for CS. Advances in medical treatment have helped reduce the risk of stroke in patients with asymptomatic CS (3). Unlike other arterial stenosis (including in lower extremities and abdomen), it seems that carotid endarterectomy (CEA) for CS plays a favorable role even when compared to CAS in terms of overall risk of stroke or death (4). The recent guideline also considers the role of CEA as important (5).
Research pertaining to CS has largely focused on the appropriate selection from amongst the three main treatment modalities, i.e., medical treatment, CEA, and CAS. This is typically based on stroke risk stratification, including assessing the symptoms, and the degree, of stenosis. Bibliometric analysis is a research method that aims to identify publication trends in a particular field with respect to authorship, journal, country, year of publication, and issues in a particular field (6). The purpose of this study was to analyze the performance and trends of CS research through bibliometric analysis.
Hallym University’s Institutional Review Board (IRB No. HKS 2020-02-017) approved the review of medical article using a publicly available database. A search of the Thomson Reuters Web of Science citation indexing database and research platform was completed on August 22, 2019. The key words used in the search were “carotid artery” and “carotid stenosis”. The retrieved articles were filtered to include only full-text manuscripts published in the English language. The filtered manuscripts pertained only to the extracranial portion of the internal carotid artery.
Data collection and statistical analysis
The retrieved manuscripts were sorted by the number of citations, a method initially developed by Paladugu and colleagues (7). The two authors (H Jun and JW Hwang) analyzed the individual articles independently to ensure their relevance to CS. Any disagreements were resolved by consensus. The top 100 most cited articles (T100) were finally selected. The variables, including the title, corresponding author, institution, country of origin, year of publication, and topic, were then evaluated. All articles were analyzed according to their topic: CEA, medical treatment, CAS, diagnosis, and CEA vs. CAS. The “medical treatment” group included comparative studies between medical treatment and correction of stenosis by CEA or CAS. The “diagnosis” group included articles pertaining to manifestations, risk factors, clinical correlations with other diseases, and diagnostic tools (ultrasound, computed tomography, and magnetic resonance imaging). The “CEA vs. CAS” group included studies that compared the outcomes of CEA and CAS. Older articles are likely to be cited more frequently because more time has elapsed since publication; to eliminate this potential source of bias, the citation rate was analyzed by dividing the citation number by the number of years since publication.
The authors retrieved 15,259 full-text English language papers from the Web of Science database. The T100 are listed in Table S1. The number of citations ranged from 5,424 for Barnett et al. (8) (“Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis”) to 230 for Mannami et al. (9) (“Prevalence of asymptomatic carotid atherosclerotic lesions detected by high-resolution ultrasonography and its relation to cardiovascular risk factors in the general population of a Japanese city: the Suita study”). The mean number of citations for all articles was 582.7±707.7.
The T100 were published between 1990 and 2016. Overall, the number of articles pertaining to CS showed a progressive increase over successive years; however, the T100 were distributed uniformly over this period (Figure 1). The oldest of the T100 was published in 1990 by Craven et al. (“Evaluation of the associations between carotid artery atherosclerosis and coronary artery stenosis. A case-control study”) (10). The most recent article was published in 2016 by Brott et al. (“Long-term results of stenting versus endarterectomy for carotid-artery stenosis”) (11).
The T100 were published across 20 journals (Table 1). Stroke published the highest number of papers (n=22, citations =7,669). The New England Journal of Medicine had the highest number of citations [15,113], although only 10 out of the T100 were published in this journal.
|Journal title||Impact factor 2018||5-year impact factor||Number of articles||Number of citations|
|New England Journal of Medicine||70.67||70.331||10||15,113|
|Journal of Vascular Surgery||3.243||3.616||8||2,463|
|Journal of the American Medical Association||51.273||46.312||5||5,216|
|Journal of the American College of Cardiology||18.639||19.068||3||1,096|
A vast majority of the T100 were published in the United States (43 publications) and United Kingdom (26 publications) (Figure 2), and most of the studies were performed in western countries. The University of Oxford had the highest number of publications among the T100 (seven publications) followed by the University of Washington (six publications) (Table 2). Eleven corresponding authors contributed to two or more papers; among these, Peter M. Rothwell had contributed to 10 publications (Table 3).
|Institution||Number of publications||Total number of citations|
|University of Oxford||7||3,235|
|University of Washington||6||2,511|
|Wake Forest University||5||5,100|
|Western General Hospital||5||5,043|
|University College London||4||2,294|
|John P. Robarts Research Institute||3||3,485|
|St George Hospital||3||2,339|
|University of Western Ontario||3||864|
|Author||Number of articles||Total number of citations|
The articles were divided into the following categories according to the main topic (Figure 3): CEA (n=22), medical treatment (n=11), CAS (n=9), diagnosis (n=44), and CEA vs. CAS (n=14). Only 2 of the T100 were published after 2011. Articles in the CEA group were consistently published over time; however, the number of publications tended to decrease over time. Most articles in the CAS groups were published between 1996 and 2005. Publications in the medical treatment group tended to increase over time. The diagnosis group continued to account for a significant proportion of articles and included four studies investigating the correlation with coronary artery disease. The number of studies in the CEA vs. CAS group showed a remarkable increase after 2006.
CEA was introduced by DeBakey (12) in 1953; it has long been considered the standard therapy for CS requiring recanalization. Ever since the first CAS study was published by Kerber et al. in 1980 (13), it is widely practiced as a viable alternative to CEA. Consistent with this, our study also revealed a consistent trend of published studies comparing CEA and CAS (Figure 3). Favorable results have been published for CEA, but similar results have recently been reported in the overall risk of stroke or death in patients with CS (4,11). Medical treatment trials for CS were initiated in the 1990s; the resultant advances in medical treatment have helped reduce the stroke risk in patients with CS (3). In recent trials (including SAMMPRIS trial), aggressive medical treatment (including antiplatelet and lipid management) was associated with decreased risk of stroke in patients with asymptomatic CS, regardless of recanalization (14). Despite advances in recanalization technology, medical treatment seems to play a more important role in CS.
Recently, the endovascular approach is an important issue in vascular disease and has greatly improved. While the number of studies pertaining to CS has increased progressively over successive years, the temporal distribution of the T100 has remained mostly steady over a long period of time (Figure 1). This likely reflects the fact that modern treatment modalities for CS have not replaced traditional treatments completely. There are several ongoing historical studies of the comparative efficacy of CEA, CAS, and medical treatment.
Bibliometric analysis can help assess research performance, scientific productivity, and publication quality (15). The number of citations is a good indicator of the quality and impact of publications. In this study, we selected the T100 according to the number of citations. By analyzing the flow of past publications, bibliometric analysis can help predict future publication trends. Therefore, bibliometric analysis is a useful tool to understand the history of a particular field.
As with any bibliometric analysis, our results are liable to be affected by several potential sources of bias, including institutional bias and influential researcher bias. Moreover, older studies are more likely to be cited because more time has elapsed since publication; this is another source of potential bias. Lastly, we analyzed only the T100 and not all CS studies; therefore, we may not have assessed the overall study trends accurately.
This bibliometric analysis of CS research provides insight into publication trends and perspective on the treatment of CS. The main treatment modalities for CS include CEA, CAS, and medical treatment; these are viable treatment alternatives and may be used in conjunction with each other. Ongoing analysis of CS research is a key imperative.
Peer Review File: Available at https://apm.amegroups.com/article/view/10.21037/apm-21-3420/prf
Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://apm.amegroups.com/article/view/10.21037/apm-21-3420/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. Hallym University’s Institutional Review Board (IRB No. HKS 2020-02-017) approved the review of medical articles using a publicly available database.
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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