A bibliometric analysis in the fields of preventive medicine, occupational and environmental medicine, epidemiology, and public health

The fields of Preventive Medicine, Occupational/Environmental Medicine, Epidemiology and Public Health constitute scientific fields, along with clinical medicine, which play an important role on people's health around the world [1–3]. Research performed in the above fields provides the basis for identifying significant health problems in the population and supports the development of knowledge-based interventions to educate people on health issues, promote health, and protect people's vulnerability to different health hazards [4–6]. Furthermore, published scientific articles on such topics promote public dialogue and provide opportunities for policy makers to address public health issues through legal interventions [7, 8].

While, the academic community strives to identify the best approach to assess the quantity and quality of research production between different geographical boundaries, languages and scientific disciplines, most scientists agree on the utility of the impact factor as well as additional adjusted indicators for international comparisons [9]. Several bibliometric analyses have been published in the medical literature on different topics [10–13]. Our group has also previously published a number of articles assessing the research production of different world regions on several scientific disciplines, however there are limited data on the bibliometric assessment of research in the fields of our present study with several reported limitations [14–22].

For example, Gehanno JF et al has reported that 1.4% of journals in the field of Occupational Health (a total of 8 journals) account for 27% of published articles in the field, while Navarro A et al have reported that one or more institutions in the United States contributed over 40% of articles in Occupational Health [18, 19]. In addition, Verbeek J et al have studied the sensitivity and specificity of search terms in identifying Occupational Health intervention studies [20].

In the current investigation, we sought to identify and quantify the research production of different world regions in the fields of Preventive Medicine, Occupational and Environmental Medicine, Epidemiology, and Public Health around the world.

The methodology we used in our study parallels other bibliometric studies performed by our research group in order to evaluate research productivity in specific scientific disciplines [14–17].

As shown in Table 1, the USA is the world leader in research productivity in the "Preventive and Occupational/Environmental Medicine" subcategory, in terms of both quantity and quality (7,280 articles, mean impact factor 1.5) of published papers. Researchers in the USA published more than one third of articles in this field. Western Europe comes second in the number of published articles (5,306), while Canada ranks second regarding the mean impact factor (1.4) along with Central and Latin America. When adjusted for GDP, Canada is the most productive region, whereas USA reclaims it leadership when data are adjusted for population size.

Similar rankings for USA, Canada, and Western Europe are seen in Table 2, referring to articles published in the field of epidemiology. It is notable that researchers in Europe publish more articles in this field compared to their own research productivity in the Preventive Medicine and Occupational Medicine subcategory, while Canada researchers rank again second when research production is adjusted for gross domestic product.

Finally, data from the 28 Public Health journals are presented in Table 3. USA again leads the research production, and there is a much bigger gap compared to the second region (Western Europe). USA researchers rank first regarding both raw and adjusted data and produce about two thirds (61%) of all published articles around the world. We also note that researchers from Oceania rank first in this subcategory, together with the USA, with respect to the mean impact factor, and come second when total product is adjusted for both gross domestic product and population size.

In all of the 3 subcategories examined, the annual number of published articles worldwide showed an increasing trend, a phenomenon that was more pronounced in the "Public Health" subcategory (Table 3), probably due to the gradual increase in the number of journals of the ISI category throughout the study period. After accumulating the data from all 3 subcategories (data not shown), USA came first in all indices, namely the number of articles (23,918), the mean impact factor (1.96), the total product (46,879), and the total product per GDP (61.1), and per million of population (167).

In our study we have quantified the research production around the world in several related public health disciplines as well as in Occupational and Environmental Medicine looking at a specific time period and adjusting our findings from different world regions for their corresponding gross domestic product and population size.

We found that researchers from the USA maintain a leadership position in the publication of scientific articles in the fields of Preventive Medicine, Occupational/Environmental Medicine, Epidemiology and Public Health similar to other scientific fields examined. The most noteworthy finding of our study is the fact that USA researchers contributed more than 60% of all articles published in the field of Public Health around the world (indexed in the reviewed databases). Even after overall adjustment for gross domestic product and population size, USA continued to lead. However, Canada researchers ranked first when scientific production was adjusted for gross domestic product in the fields of Preventive Medicine, Occupational/Environmental Medicine and Epidemiology. Furthermore, we found that four regions of the world with more than 50% of the world's population have minimal contribution in the scientific fields studied.

Our results support previous findings suggesting that the majority of research published in scientific journals is carried out in the developed world [18]. It is also notable that USA evolved as the strongest leader in the field, since it demonstrated the highest productivity in most fields examined. The above finding is not a surprise given the long tradition of agencies and institutions in the USA in implementing research and population-based public health programs [26, 27]. Similar observations with respect to public health research would also apply to Canada [28]. In addition, our study reveals a significant gap in the participation of certain world regions in scientific research in the above fields examined at least with respect to the published literature in the English language [29–31].

Several limitations of our current investigation have been cited previously and would also apply [14–17]. Most of the limitations are related to the databases used to retrieve articles as they consist largely of English-language journals therefore possibly contributing to selection bias due to language barriers. In addition, the above databases do not represent all scientific and biomedical journals published. Other limitations include the incorrect citation of origin for the authors, and the use of impact factors as an indicator of research quality [32]. Finally, many articles of public health importance appear in journals other than those we included in our searched categories. Nevertheless, we believe that comparisons made even under known or unknown limitations, are useful and could provide important insight with respect to the direction, amount, and impact of research productivity around the world [33].

In summary, we found that the USA, Western Europe, Canada and Oceania are the leading regions in the research production in the fields of Preventive/Occupational/Environmental Medicine, Epidemiology and Public Health, with the USA being far ahead especially in the subcategory of Public Health. We believe that our findings clearly indicate the need to promote research in the above fields in less developed regions of the world. Promoting research in less developed areas such as Africa, Asia, Latin America and Eastern Europe, may involve but not limited to the development of infrastructure including research and academic institutes, the improvement of current collaborative partnerships with developed nations, increased sponsorship and support from world agencies such as the World Health Organization and the United Nations, and the implementation of programs including free access to online journals and translation services for scientific articles published in languages other than the English language. All of the above are likely to increase research and development in the less developed regions of the world and improve peoples' health through the diffusion of knowledge and the implementation of large-scale research projects.