What’s known on the subject? and What does the study add?

Bibliometric analysis on retrograde intrarenal surgery. This study is the first study that makes a holistic analysis of the articles about this issue. One of the notable findings of this study is that Turkiye is among the world countries that produced the highest number of publications about this issue and the hospitals where this technique is used most are located in Turkiye.

Introduction

Urinary system stone disease encompasses the kidneys, ureter, bladder, and urethral calculus. It is a commonly encountered health problem affecting 2-3% of people and causes serious complications when it is not treated. The retrograde intrarenal surgery (RIRS) technique performed under general anesthesia is done using a thin instrument, 3 mm in diameter (flexible renoscopy), with a light source that enables monitoring with an optic fiber by passing from the urethra (urinary canal) and bladder (urinary bladder) to the path that connects kidneys and bladder (ureter), in order to break the stone located within the kidney. Renal stone is broken using a laser power source that can pass through renoscopy and the big stone parts are taken out after the breaking procedure; the fragments that are now in powdered form are removed from the kidney (1,2).

Today, RIRS enables the successful treatment for most small or medium size renal stones, without any need for open surgery or percutaneous nephrolithotomy (PCNL). This method makes it possible to access the kidney from the abdominal wall without needing to open any holes; renoscopy that could be bent by entering from the urinary canal and laser enable the complete breaking and removal of the stones. Using this method, patients could be discharged from the hospital in a shorter period and begin to live as before (3-5).

The treatment of renal stones has recently undergone significant changes. The treatment options include open surgery, as well as the less invasive PCNL, extracorporeal shock wave lithotripsy (ESWL), and RIRS (6). With the increase in surgical experience, RIRS has become an important and acceptable treatment option for renal stones for all age groups, stone sizes, and localizations (7).

Bibliometric analyses enabled the identification of the most effective and top-cited studies and journals, through the statistical analysis of articles published with regard to a specific topic, specific research field, journal, or a country (8-11). They also enabled us to explore the collaborations between countries, authors, and institutions.

Bibliometric studies involve the investigation of the relationship between publication productivity and various factors possible (12-15). There have been several bibliometric studies in the medical field in recent years. The value of bibliometric studies has been increasing as a result of the increased number of publications in literature day by day (16).

The prevalence of renal stones has been increasing worldwide (5,17), and surgical methods have changed over time. However, there is no comprehensive bibliometric analysis of this method in the literature This study aimed to conduct a bibliometric analysis of all the articles regarding RIRS published between 1980 and 2019.

Material and Methods

The literature review was done using the following keywords: “RIRS” and “flexible ureterorenoscopy/flexible ureteroscopy/FURS), in the “title” part of the search. [Access codes: (title: (retrograde intrarenal*) or title: (flexible uretero*) or title: (RIRS) or title: (FURS) timespan: 1980-2019. indexes: SCI-Expanded, A&HCI, SSCI, CPCI-S, BKCI-S, CPCI-SSH, BKCI-SSH, ESCI) and access date: August 01, 2020]. Through this search, all the articles that were published between 1980 and 2019 on this topic were accessed and downloaded from the Web of Science (WoS) database. The articles were analyzed using bibliometric methods. VOSviewer (Version 1.6.13) package program was used for the bibliometric web visualizations. The world map was drawn using an online web site (http://lert.co.nz/map/).

Results

Totally, 1378 publications were found as a result of the literature search, of which 619 were articles, 544 were Meeting Abstracts, 109 were Editorial Materials, 53 were Reviews, 33 were Letters, 19 were Proceedings Papers, and 20 were other publications (Early Access, Correction, Book Chapter, Note). This study included the bibliometric analysis of 619 publications only; all of which were articles. Of these articles, 90.3% were English (n=559), and the others were French (n=34), Spanish (n=22), Turkish (n=3), and Korean (n=1).

The 619 articles accessed received 8518 citations (without self-citations 5549) in total, and the mean citation number per article was found to be 13,76, while the H-index of all the articles was 44.

Active Research Areas

The top 10 research areas of the published articles included Urology and Nephrology (515: 83.2%); General Internal medicine (35); Surgery (30); Experimental Medicine Research (25); Multidisciplinary Sciences (11); Pediatrics (10); Pharmacology and Pharmacy (4); Radiology, Nuclear Medicine, and Medical Imaging (3); Anatomy Morphology (2); and Biotechnology Applied Microbiology (2).

Development of Publications

The distribution of the articles is demonstrated in Figure 1. The increase in the number of articles has been significant since 2011, and a notable increase was found after the year 2014.

Active Countries

A total of 51 countries had made publications on this topic; Figure 2 demonstrates the rank order of 23 countries that produced the highest number of articles. The network map of international collaborations between the 30 countries that produced a minimum of three publications is displayed in Figure 3.

Active Authors

Table 1 presents the top 25 authors producing the highest number of publications about this issue.

Active Organizations

The top active organizations involved and organizations that produced the highest number of publications are demonstrated in Table 2.

Active Journals and Citation Analysis

Table 3 presents the active journals producing the highest number of publications regarding this topic. The number of citations and the number of citations per article are shown in the last column of Table 3. The Citation network visualization map among the journals is given in Figure 4.

Most Cited Articles

Table 4 displays the top 15 articles that had received the highest number of citations (18-32).

Co-citation Analysis

A total of 4484 publications were cited in the references section of the 619 published articles. The studies receiving the highest number of citations were those conducted by Dindo, 2004 (Citation: 88) (33); Breda, 2009 (Citation: 80) (21); Breda, 2008 (Citation: 69) (20); Traxer, 2013 (Citation: 65) (18); and Bozkurt, 2011 (Citation: 58) (25). There were 33 articles that received citations at least 30 times. The density map of these articles is shown in Figure 5.

Trend Topics

There were 697 different keywords in the 619 articles. Figure 6 shows the network map of the cluster analysis results conducted with 71 keywords that were used in minimum of four different articles. The network map of trend words analysis is given in Figure 7.

Discussion

In line with the increase in the importance of RIRS, the importance of the number of publications and citations has also increased. Particularly, the number of publications has increased rapidly since 2011, and it has reached approximately 80 articles in recent years. Turkiye was found to be the most productive country with regards to RIRS. Although the publication productivity of developed countries such as the USA, China, France, United Kingdom, Germany, Italy, Spain, and Japan reveals that publication productivity is closely related to financial power; it is also important to note the contribution of countries such as Turkiye, India, Brazil, Chili, and Romania.

The analysis performed to detect the collaboration between the countries showed that the collaborations were in clusters of geographical location. Developing or undeveloped countries could be encouraged to create collaborations on this issue topic.

The journals that had the highest contribution to the literature were Journal of Endourology, Urology, Journal of Urology, Urolithiasis, and World Journal of Urology. As per the total number of citations, the Journal of Endourology, Urology, Journal of Urology, and BJU International were the effective journals. The journals receiving the highest number of citations per article were European Urology, Journal of Urology, BJU International, Urology, and Urological Research. Researchers could be recommended to consider these journals for studies that they would like to receive more citations. As for the journals addressing Turkiye, the notable journals were the Journal of Urological Surgery and Turkish Journal of Urology.

The articles with the highest total number of citations included the articles entitled “Prospective Evaluation and Classification of Ureteral Wall Injuries Resulting from Insertion of a Ureteral Access Sheath During RIRS” written by Traxer and Thomas (18) and “Ureteral access sheath provides protection against elevated renal pressures during routine flexible ureteroscopic stone manipulation” written by Auge et al. (19). Apart from these studies, the top-cited articles according to the average number of citations included the studies entitled “Flexible Ureteroscopy and Laser Lithotripsy for Multiple Unilateral Intrarenal Stones” and “Flexible ureteroscopy and laser lithotripsy for single intrarenal stones 2 cm or greater - Is this the new frontier?” by Breda (20,21), respectively. The top-cited Turkish study entitled “RIRS Versus Percutaneous Nephrolithotomy in the Management of Lower-Pole Renal Stones with a Diameter of 15 to 20 mm” was written by Bozkurt et al. (25) in the Journal of Endourology.

According to the co-citation analysis results, the studies conducted by Dindo et al. (33), Breda et al. (20,21), Traxer et al. (18), and Bozkurt et al. (25) were cited the most in the references sections of the articles. Researchers interested in RIRS are recommended to first read these studies.

Keyword analyses indicated eight different clusters, and the cluster centers included RIRS, flexible ureteroscopy, ureteroscopy, and urolithiasis. While previous percutaneous nephrolithotomy and ureteroscopy topics were searched, especially after the year 2000, laser and RIRS topics were searched, which is considered to be as a result of using holmium laser in RIRS operations in 1995.

Study Limitation

The limitation of the present study is that it did not search the PubMed and Scopus databases. WoS database was preferred, as the journals with a high impact factor are indexed there and it is a more reliable database in terms of citations (11,34,35).

Conclusion

With the increase of the importance of RIRS, a less invasive technique for the treatment of urinary system stone diseases, the present study is the first of its kind study to conduct a holistic analysis of the articles on this issue. The study is believed to guide physicians, academics, and students in studying RIRS, on topics such as effective journals, top-cited studies, trend topics, and the most productive countries. One of the notable findings of this study is that Turkiye is among the world countries that had the highest number of publications on this topic and the hospitals where this technique is used are mostly located in Turkiye.

Ethics

Ethics Committee Approval: This article does not contain any studies with human participants or animals performed by any of the authors.

Informed Consent: For this type of study formal consent is not required.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Concept: M.M.B., M.E., Design: M.M.B., M.E., Data Collection or Processing: M.E., E.D., Analysis or Interpretation: M.E., E.D., Literature Search: M.E., E.D., Writing: M.M.B., M.E.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.