Bibliometric analysis is an effective measure of numerical analysis of the scientific contribution in a specific field and period of time, as well as of the relationships between these publications ; i.e. to ascertain which authors, scientific centers, countries and journals have the greatest influence in the advances in the given field of science, and especially in medicine .
Intragastric balloons as an alternative option for obesity treatment were first introduced in the late 1980s as an instant restrictive procedure, reducing the active gastric space to accommodate food and thus increasing satiety [16, 20]. Today, almost 30 years later, the idea of using a balloon as a space-occupying device in the stomach has proved itself, filling the void between pharmacotherapy and bariatric surgery. It is a less expensive, minimally invasive, and easy-to-perform nonsurgical procedure, the advantage of which is its full reversibility and low rate of reported complications, ensuring a significant weight loss in selected obese patients . Thousands of devices are now placed globally each year and the literature contains numerous studies of methodology, results and the applicability of the various balloon types [2, 4, 21, 22].
To our knowledge, this is almost the first Bibliometric study ‒ if we exclude a previous study from our group published only in the proceedings of a non-medical congress [22 ‒ which not only presents the dynamics of article production in this field, but also attempts to analyze the authors’ scientific productivity and to identify the academic institutes as well as NHS centers systematically dealing with intragastric balloons placement. The last two decades have seen a 5-fold increase in both the number of publications and the number of cases included in each study; of course, this may be associated with the population density of most countries involved, i.e. Brazil with 5874 cases, Italy with 2515 and Egypt with 1600, but there is also undoubtedly a progressive general drive worldwide towards less invasive, but reliable procedures, .
In the bibliographic analysis of country of origin, the numerical superiority of Italy is obvious, more than double in relation to Brazil and USA. These findings are easily explained by the fact that intragastric balloons were not FDA approved until 2015, and therefore banned from the largest market in the world: the USA. This is also noticeable in the analysis of balloon type: a progressive polarization towards two balloon types - the old-time classic fluid-filled balloon [Orbera or similar] applied in hundreds of thousands of cases and the newer, swallowable fluid and/or gas filled ones, with one or two bubbles, making their first exploratory steps. This difference in numbers between Orbera and all the other types may be explained by the great popularity of the Orbera in Europe, due to its safety and effectiveness after a more than a decade as the sole balloon. One way another, the numbers of publications resulting from use of the Orbera show a considerable and consistent increase over the years.
The fluid-filled Orbera-related publications exponentially increase over our period of study, recording the balloon’s effectiveness, its long-lasting positive effects on weight loss and the reduction in comorbidities. Later publications relating to new balloon types attempt to present them as comparable to the Orbera, in particular, promoting their easier handling for placement and removal.
Apart from the statistical figures, our Bibliometric study provides a new insight into which countries have played a key role in understanding the advantages and promoting the use of intragastric balloons for obesity management. Moreover, the detailed analysis of related publications covering two decades could help to identify changes occurring in scientific trends over this period . It has thus become clear that many centers with long-term experience with the Orbera balloon consider it trustworthy and reliable, and are disinclined to change just for the sake of a study . On the other hand, new physicians in this era, or new markets, as big as the USA or as small as the Czech Republic, are trying the more modern balloons.
As regards cooperation between countries, analyzed in terms of the affiliations of all authors, 11 out of the 33 countries ‒ sharing a total of 15 publications ‒ have conducted at least one such collaborating project. It is of interest that the United States has a central position in terms of co-authorship, having collaboration with 9 different countries, although it is not the dominant country in terms of the number of overall publications. (This may relate to the restrictions on use of intragastric balloons before 2015). Italy, the country with the majority of publications (37) had only 4 performed in collaboration with other countries ‒ probably due to the extensive intra-country network, leading to 7 national collaborating studies.
The bibliometric network visualization and mapping by means of the Biblioshiny [https://bibliometrix.org] and Bing GeoData software enabled us to present the worldwide distribution of this endoscopic procedure, as well as the scientific collaboration between countries. However, this co-operation was clearly not in the field of ideas exchange for scientific research, but rather merely collaboration among centers or even countries in order to increase the number of cases presented and achieve valuable statistical documentation. While the largest intra-country network collaboration, 8 centers/cities, is the Italian - they present their early experience with the Orbera balloon in 2515 obese individuals - the majority of cases come from Brazil − 5874 Orbera balloons from only 4 centers/cities, which is unsurprising considering the size of their population.
A similar collaboration is that of USA institutes and private practice centers, leading to a valuable number of cases with the swallowable gas-filled balloon, the Obalon − 387 cases in the 2018 publications and 1343 in the following year, all balloons in the initial year of U.S. commercialization. Half of the pioneering research into intragastric balloons has come from European countries and started with the Orbera. However, as newer balloons appeared on the market, research evolved apace to include these new models: The Reshape Duo, presented in the REDUCE pivotal trial , in 326 cases [187applied the dual balloon system and 139 sham endoscopy plus diet and exercise alone], has been of significant impact on the knowledge of newest balloon technology; this is clear from the number of citations [n = 211] of only the one publication.
It is well known that the number of times an article is cited is a good way of measuring its impact over a period of time on a specific field of science, and this in turn allows evaluation of both the authors and the journal itself . However, it is important to understand that gathering citations is a time-dependent process, a new study requiring at least 2–5 years accumulating enough citations to be used as a reliable bibliometric indicator . Thus, in the present Bibliometric analysis, 8 out of 14 and 5 out of 12 publications of the years 2021 and 2020, respectively, have still gained 0 citations.
It is also of interest to mention that despite the large number of journals used ‒ 48 journals for 164 publications ‒ just one, Obesity Surgery which published 86 articles, accounted for 52.44% of the total number of papers; while, 32 journals accounted for 66.7% of the total number of journals hosting only one article each, i.e. publishing 19.51% of the total number of publications. It can thus be argued that Lotka’s law  applies also to the authors of the articles under study, although being over-estimated; however this analysis is outside the main topics of our study.
The present study has some limitations. First, the Scopus and the PubMed databases were only used for data extraction, and the PubMed only for the citations of the articles under analysis; this decision being based on the finding that PubMed presents more citations in relation to Scopus for the same articles . Second, we unfortunately excluded 4 articles written in non-European-language journals, only because of our inability to understand these languages. Third, we manually collected all the authors’ names and credited them as authors, rather than only the first or the corresponding author, as the bibliometry software suggests. Fourth, we tied to map the countries/cities where there are scientifically valuable centers dealing with the application of intragastric balloons through their scientific productivity. This, in no way means that there are no other trustworthy centers, worldwide, which do the same, but don’t like or don’t have time to present their results through publication in reliable medical journals – unfortunately, there is no other method of identifying them; and, fifth our purpose was to identify these centers through their scientific publications. Finally, except in rare cases we generally named cities and not institutes, which is why some authors’ affiliations changed over time.
In conclusion, through the present bibliometric analysis of scientific publications we identify the productive centers in various countries/cities and classify them in relation to the number of published articles, collaboration, number of cases reported and number of citations gained. Of the 164 publications considered eligible for analysis, the lists are topped by: Italy with 37 publications; the USA, as having participated as collaborators with 9 different countries; the fluid-filled Orbera balloon used in 126 studies; the journal Obesity Surgery with 86 publications; Brazil with 5874 cases; Lorenzo M, and Genco A, co-authors from Italy with 14 and 12 publications, respectively; and the article by Genco A, et al published in Obesity Surgery 2005  having being cited 441 times. All other balloon types are related to much lower productivity; unsurprising since their history begins only from 2007.