Keywords
INTRODUCTION
Cardiovascular disease (CVD) is the primary cause of morbidity and mortality in the European Union (EU), the United States, and other industrialised nations. In the EU it is estimated that 80 million people are at risk of suffering a vascular accident within the next ten years, and that the number of deaths caused by CVD will increase by 60% between 2000 and 2020.1 Resources aimed at these diseases have been estimated at €169 trillion per year, of which 62% is spent on treatment, prevention, and control.2
Scientific research is considered one of the pillars of economic development and growth in both industrialised and less developed nations.3 In recent years the publication of research articles has increased considerably in all biomedical areas, putting Spain in seventh position in Europe and eleventh worldwide during the period 1994-2002.4 Spanish scientific productivity in the cardiovascular field has also increased significantly in recent years. According to the Institute for Scientific Information Science Citation Index database,5 during the 1990-1996 period, the total cardiovascular productivity of Spanish authors increased by 83% and remained at 80.9 % between 1994 and 1999.6
The amount of economic resources and investments aimed at research is not exactly known, given the diversity of funding sources (regional, national and supranational, both public and private).3 However, the scale is such that it is necessary to utilise measures or indicators which can quantify research results and their impact. Bibliometric indicators, linked with other economic and social indicators, allow for the precise assessment of the developmental state of research and therefore provide a basis for political and scientific decision making.4-7
The position occupied by Spain in Europe and worldwide with regard to cardiology research is not known, nor if this position corresponds to Spain's current status of eighth world economic power in terms of gross domestic product. An understanding of the Spanish position is fundamental in being able to remedy insufficiencies, as well as reaching a level of critical understanding that would allow for the advancement of knowledge in the field.3,8 The aim of this study is to determine the position held by high-quality Spanish cardiology research both in Europe and worldwide, and its progress in recent years.
MATERIAL AND METHOD
Database Selection
The Science Citation Index Expanded (SCI-E) database from Thomson Reuters was used to examine Spanish productivity in the cardiovascular field.9 The SCI-E is routinely used in studies analysing scientific activity, since this database encompasses all scientific and technological fields and allows us to examine the repercussions or impact of publications after the publishing date. This study covers the 5-year period 2003-2007. All analysed documents were original articles: revisions, editorials, and letters were not included, neither were abstracts of communications to conferences, bibliographic articles, corrections, reprints, or announcements.
Strategy for Document Recovery and Bibliographic Searches
The downloading of information from the SCI-E was carried out online, using the Web of Knowledge10 platform, version 3.0, in January 2009.
With the aim of collecting all scientific productivity in the field, we selected articles published in all 78 journals included in the Cardiac & Cardiovascular Systems (CCS) category under Journal Citation Reports (JCR) during 2003-2007. During this period new journals were added to the JCR and some were removed. This fluctuation in the category is as follows: 2003: 70 journals; 2004: 71 journals; 2005: 72 journals; 2006: 74 journals; 2007: 74 journals.
To compare Spanish cardiological productivity with that of other countries, articles from each of the 27 European Union member states, as well as Norway and Switzerland, were searched. The European Union countries are as follows: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom. To assess the position of Spain and other European countries among the rest of the world, articles from the United States, Canada, Mexico, Brazil, Japan, Australia, China, India, New Zealand, and Russia were also searched. These countries were selected due to being the most productive nations in each continent.
With the aim of garnering cardiovascular research of the highest scientific quality from both Spain and the above-mentioned countries, articles in journals from the first quartile of the CCS-JCR category were identified. The number of journals included in the first quartile did not remain constant during the 5-year period, with 18 in 2003, 2004 and 2005, and 19 in 2006 and 2007. Of the 24 journals identified in the category, only the 13 that were included in the first quartile for all 5 years were selected for analysis in this study.
To identify the quality and repercussions of published articles, the number of citations received by each country and the average number of citations per article were determined. This average was reached by dividing the total citations received by the total number of published articles. The time period for the number of citations was from the date of each article's incorporation into the SCI-E up to the date of the bibliographic search (January 2009).
Finally, in order to determine the productivity of each country, the relationship between the number of articles and either the population or gross domestic product (GDP) was determined.
RESULTS
Scientific Contribution to All Journals in the CCS-JCR Category
The total number of original articles published worldwide in journals within the CCS category during the 5-year period 2003-2007 was 54 968. Of this number, 22 389 (39%) were published by the 27 EU nations, 20 625 (35%) by the United States, and 15 346 (26%) by countries in the rest of the world. Those European countries which published the most articles were Germany (n=5445; 9.92%), United Kingdom (n=4557; 8.29%), Italy, (n=3546; 6.45%), France (n=2781; 5.06%) and the Netherlands (n=2471; 4.5%). Spain takes 6th place (n=1542; 2.81%) (Table 1). Other countries in addition to the United States that contributed over 1% of worldwide output are: Japan (n=5680; 10.33%), Canada (3268; 5.95%), Australia (n=1115; 2.03%), China (n=1057, 1.92%), Russia (n=775; 1.41%), and Brazil (n=640; 1.16%). Spain therefore holds 9th place overall in the world rankings. Figure 1 shows the annual progress in the number of articles published by the EU's most productive nations. The majority of countries maintain a steady output for the whole period, and significant increases in the number of articles can only be seen for Italy (from 595 articles in 2003 to 797 in 2007), and a minor decrease for France (from 601 articles in 2003 to 536 in 2007). Revista Española de Cardiología (Spanish Journal of Cardiology), which published 460 original articles during the 5-year period, contributed 30% of the total articles published by Spanish institutions in CCS-JCR journals, this being 0.84% of worldwide contributions.
Figure 1. Annual development of EU-27 countries with the highest contribution to the CCS category.
Scientific Contributions to All First-Quartile CCS-JCR Journals
The total number of original articles published by all countries in first-quartile journals was 26 887, this being 48.91% of total contributions. Of this number, the United States published 13 672 articles (46%), the EU-27 10 834 (37%), and other countries published 4905 (17%). It should be noted that the sum of original articles from the EU-27, United States and rest of the world is greater than the total number of first quartile articles. This is because some articles were collaborations between countries in different groups.
Those European countries which published the largest number of articles are as follows: United Kingdom (n=2708; 10.07%), Germany (n=2541; 9.45%), Italy, (n=1834; 6.82%), the Netherlands (n=1635; 6.08%), and France (n=1277; 4.75%). Spain again holds 6th place, but with approximately half the number of articles published by its predecessor (n=640; 2.38%). Besides the United States, countries whose participation exceeded 1% of worldwide output are as follows: Japan (n=2048; 7.62%), Canada (n=1994; 7.42%), Australia (n=719; 2.67%), China (n=448; 1.67%), and Brazil (n=287; 1.07%). Spain holds 10th place in the world ranking (Table 1).
Figure 2 shows the annual progress in the number of articles published in this selection of journals by the EU's most productive nations. Again we see an increase in articles from Italy (rising from 324 articles in 2003 to 392 in 2007), and a minor decrease in articles from Germany (from 555 in 2003 to 470 in 2007), United Kingdom, and France.
Figure 2. Annual production of EU-27 countries with the highest contribution to journals in the first quartile of the Cardiac & Cardiovascular Systems category.
Table 2 shows the number of articles published by each of the 27 EU countries (including Norway and Sweden) in those journals included in the first quartile of the JCR, as well as a comparison between the EU-27 and the United States, Japan, Canada, Australia, Brazil, China, New Zealand, Mexico, India, and Russia. Of the 13 journals included in this selection, 9 are edited in the United States (US) and 4 in the United Kingdom (UK). The number of articles published in US journals was 19 941, while the number published in European (EU) journals was 4003. The number of US articles published in all US journals exceeds that of EU articles except in the case of the Journal of Thoracic and Cardiovascular Surgery (440 US articles compared with 537 EU), while EU articles exceed US articles in EU journals except in the case of the Journal of Molecular and Cellular Cardiology (392 US articles compared with 234 EU). Figure 3 compares the number of first-quartile US and EU articles with the total overall number published in the first quartile of each journal. In overall figures, the percentage of EU articles published in US journals (35.13%) exceeds that of US articles published in EU journals (28.18%).
Figure 3. Comparison of original articles from the EU-27/US/rest of world published in journals in the first quartile of the Cardiac & Cardiovascular Systems category.The EU-27 data originates from information from all countries combined using the Boolean operator OR, which identifies as a single document any collaboration between different countries. Am Heart J indicates American Heart Journal; Am J Cardiol, American Journal of Cardiology; Am J Physiol-Heart C, American Journal of Physiology-Heart and Circulatory Physiology; Cardiovasc Res, Cardiovascular Research; Circulation, Circulation; Circ Res, Circulation Research; Eur Heart J, European Heart Journal; Heart, Heart; J Cardiovasc Electr, Journal of Cardiovascular Electrophysiology; J Heart Lung Transpl, Journal of Heart and Lung Transplantation; J Mol Cell Cardiol, Journal of Molecular and Cellular Cardiology; J am Coll Cardiol, Journal of the American College of Cardiology; J Thorac Cardiov Sur, Journal of Thoracic and Cardiovascular Surgery.
Those journals containing the largest number of articles by Spanish authors were American Journal of Cardiology (n=91), European Heart Journal (n=80) and Journal of the American College of Cardiology (n=68), while those with the fewest number of Spanish articles were the Journal of Molecular and Cellular Cardiology (n=9) and the Journal of Thoracic and Cardiovascular Surgery (n=15) (Table 2).
Comparison Between Articles Published in First-Quartile Journals and Those Published in the Entire CCS-JCR Category
Those countries with the highest percentage of articles published in first-quartile journals were: Latvia (66.67%), Netherlands (66.17%), Belgium (59.68%), United Kingdom (59.43%), and Denmark (58.67%) (Table 3). If no correction factor were applied, Germany would hold 16th place, France 18th, and Spain 21st. However, some of the countries leading this table published very few articles (for example, Latvia published only 9 during the 5-year period). If a minimum threshold of 500 articles were applied, the table would be led by the Netherlands, followed by Belgium, United Kingdom, Switzerland, Italy, Sweden, Germany, France, and Spain, which held 9th place with 41.5% of articles (24.67 percentage points below the Netherlands and 6.89 percentage points below the EU-27 average). Worldwide, the EU-27, with 48.39%, came behind the United States (66.29%), Australia (64.48%), and Canada (61.02%). Figure 4 illustrates the proportion of articles published in first-quartile journals by the EU-27, United States and rest of the world compared to those published in the entire CCS category.
Figure 4. Contribution of the EU-27, US and rest of the world to the total contributions in the CCS category (left) and to contributions in first-quartile journals (right).
Citations Received by Articles Published in CCS-JCR Category Journals
Journals in this category received 574 993 citations, of which 285 914 correspond to the United States (49.72%) and 252 408 to the EU-27 (43.90%). The number of citations received by the main European countries was as follows: Germany (n=70 679; 12.29%), United Kingdom (n=62 751; 10.91%), Italy, (n=43 281; 7.53%), Netherlands (n=39 781; 6.92%) and France (n=33 121; 5.76%). Five countries received much fewer citations but still exceeded 10 000: Sweden (n=15 704; 2.73%), Spain (n=15 359; 2.67%), Belgium (n=13 586; 2.36%), Switzerland (n=12 039; 2.09%), and Denmark (n=10 005; 1.74%), meaning that Spain holds 7th place in the EU for number of citations received. Revista Española de Cardiología received 1936 citations during the 5-year period, this being 0.34% of the total citations received by CCS-JCR category journals.
Worldwide, those countries which received over 1% of citations are as follows: Canada (n=41 497; 7.22%), Japan (n=44 773; 7.79%), Australia (n=16 169; 2.81%), China (n=9169; 1.59%), and Brazil (n=6343; 1.1%). Spain therefore holds 11th place overall in the world rankings (Table 1).
Citations Received by Articles Published in First-Quartile CCS-JCR Category Journals
First-quartile journals received 464 991 citations, of which 253 273 correspond to the United States (54.47%) and 204 674 to the EU-27 (44.02%). With regard to the number of citations received by European Union countries, in first place was Germany (n=58 486; 12.58%), followed by the United Kingdom (n=54 308; 11.68%), Italy (35 702; 7.68%), Netherlands (n=35 279; 7.59%), and France (n=28 038; 6.03%). Four countries received much fewer citations but still exceeded 10 000: Sweden (n=12 399; 2.67%), Spain (11 998; 2.58%), Belgium (11 935; 2.57%), and Switzerland (11 014; 2.37%), meaning that Spain holds 7th place in the EU for number of citations received.
Worldwide, other countries which received over 1% of citations are similar to those mentioned above: Canada (n=35 975; 7.74%), Japan (n=29 312; 6.3%), Australia (14 367; 3.09%), China (n=6816; 1.47%), and Brazil (n=4 998; 1.07%). Spain again holds 11th place in the world ranking (Table 1).
Comparison of the Number of Citations Received for First-Quartile Journals and That Received for the Entire CCS Category
If a minimum threshold of 500 articles is established, the largest percentage of citations corresponding to first-quartile journals is that of Switzerland (91.49%), followed by the Netherlands (88.68%), Belgium (87.85%), United Kingdom (86.55%), and Denmark (85.97%). Australia leads worldwide (88.86%), followed by the United States (88.58%), Canada (86.69%), and the EU-27 (81.09%). Spain holds 12th place in Europe and 19th place worldwide (78.12%) (Table 3).
Average Citations per Article
The distribution of European nations in all CCSJCR category journals according to the "average number of citations received by published articles" indicator (av) should be observed with caution, as this figure is again distorted by the leadership of countries which have published very few articles. If only countries with a minimum of 500 published studies are taken into account, the ranking is led by the Netherlands (av=16.10), followed by Finland (av=14.90), Denmark (av=14.82), United Kingdom (av=13.77), Belgium (av=13.49), Sweden (av=13.41), and Germany (av=12.96). Spain holds 12th position (av=9.96), with a European average of 11.27 (Table 1).
Note that, at worldwide level, New Zealand has the same rate as the United States (av =13.86); however, this is due to the fact that New Zealand made very few contributions (257 articles over the entire 5-year period, compared with 20 625 from the United States). Using the same criteria as mentioned above (minimum of 500 published articles), Australia leads the ranking (av=14.50), followed by the United States (av=13.86), and Canada (av=12.70). According to this indicator, Spain holds 15th place in the ranking, ahead of Japan, Russia, and China (Table 1).
The distribution of the European countries according to the "average citations per article in first-quartile CCS-JCR category journals" indicator again appears distorted by nations which have published very few articles, such as Ireland (av=25.13), Poland (av=23.98), and Finland (av=23.45). If only countries with a minimum of 500 published studies are taken into account, the ranking is led by Germany (av=23.02), followed by France (av=21.96), Netherlands (av=21.58), Sweden (av=21.49), and the United Kingdom (av=20.05). Spain holds 9th position (av=18.75), 14 hundredths below the European average (av=18.89). Russia hold the highest worldwide rate (av=28.94), but again this is due to the country's very low number of contributions (31 articles during the whole 5-year period). Using the same threshold as before, Australia leads the ranking (av=19.98), followed by the European Union (av=18.89), United States (av=18.52), and Canada (av=18.04). According to this indicator Spain holds 10th place in the ranking, surpassed only by Australia among the non-European nations, and above the United States and Japan.
Productivity Relative to Population and Gross Domestic Product (GDP)
Table 4 shows the productivity of each EU-27 country relative to its population. The Netherlands leads, with 15.11 articles per 100 000 inhabitants, followed by Switzerland (n=13.77), Sweden (n=12.85) and Denmark (n=12.39). Spain takes 15th place with 3.47 articles. The average for EU-27 countries was 4.52, below Canada (n=9.79), the United States (n=6.85), New Zealand (n=6.24) and Australia (n=5.46), and roughly equal with Japan (n=4.46).
Productivity relative to gross domestic product (GDP) is led by the Netherlands (n=43.58), followed by Sweden (n=35.35), Switzerland (n=33.17), Greece (n=32.87), and Belgium (n=30.07). In this case Spain holds 18th place (n=14.68), with a rate similar to that of France (n=14.70), this being below both the EU-27 and US averages (n=18.14 and 19.69, respectively). Outside the EU, Canada leads with 34.73 articles, followed by New Zealand (n=30.13) and Australia (n=20.70) (Table 5).
DISCUSSION
Cardiovascular medicine has garnered considerable success in recent years, developing therapies for the prevention and treatment of numerous diseases, substantially reducing their morbidity and mortality.11 Despite these diseases being the principal cause of death in the United States, their mortality rate has decreased by 63% thanks to significant investments made over the last 30 years.12 However, an increase in life expectancy, together with socioeconomic changes in industrialised countries over recent decades, means there has been an increase in the prevalence of CVDs. This high prevalence has meant that cardiovascular research arouses the greatest amount of interest in our society and has become a priority biomedical research field in a large number of developed nations.5
The publication of original Spanish articles in the CCS-JCR category has moderately increased since the end of the 5-year period analysed in this study, with an annual increase of ten articles from 2003 to 2007. Spain holds 6th place in the EU-27, behind Germany, the United Kingdom, Italy, France and the Netherlands, and 9th place worldwide, behind the United States, Japan, and Canada. This gives the country an advantage in the Essential Science Indicators world rankings, published by Thomson Reuters in the ISI Web of Knowledge13: Spain holds 10th place in the Clinical Medicine category but, taking into account all scientific categories, maintains 9th position overall. It is interesting to note that those countries most recently incorporated into the EU are at the bottom of the table, with only Poland notable for its contribution. The EU-27 outperforms the United States in the total number of original articles published in CCS-JCR category journals (39% compared with 35%). However, if only those articles with the highest level of scientific excellence are considered, ie, those published in journals included in the first quartile of the CCS-JCR category, the United States outperforms the EU-27 (46% of all articles compared with 37%) (Figure 4). It is noteworthy that the United Kingdom outperforms Germany, and that Spain maintains 6th position in the European rankings even though the country published approximately half the number of articles of the preceding country, France, and one third of the number produced by Italy. Spain drops one position at world level, taking 10th place and once more being surpassed by Australia. As we have seen, the highest percentage of articles published in first-quartile journals, compared with the category as a whole, corresponds to the Netherlands. Spain remains in 9th place. In the world rankings, the EU-27 is behind the United States, Australia, and Canada. As we have detailed previously, a minimum publication threshold of 500 articles was applied in generating these rankings. Without this, countries such as Latvia and Ireland would hold leading positions as a result of having published very few articles, although the majority of these were in first-quartile journals.
The fact that EU-27 researchers lead in terms of number of articles published, surpassing even the United States, is also seen in other areas; as is the fact that Canada leads the ranking for scientific productivity relative to population and GDP.14 This position for Canada is logical, since Canada has a high level of scientific and technological development but a small population and GDP in comparison with other developed countries. This can also be seen in Europe, where small countries such as the Netherlands, Sweden, Switzerland, Greece and Belgium are high in the rankings, and Spain holds an unfavourable 18th position, although similar to France, and comes below the average for EU-27 countries. The situation is similar when productivity is analysed as relative to population: again small countries lead, such as the Netherlands, Switzerland, Sweden and Denmark, and Spain holds 15th position, again below the EU-27 average.
The difference in scientific productivity observed between countries is due to a number of different factors, including availability of resources, existence of consolidated research centres, even differing individual and scientific traditions. That cardiovascular research is predominant in Northern and Western Europe and North America is logical, as these are developed countries with strong economies, and the amount of funds spent on cardiovascular research and patient care is very high. It is well known that small countries such as the Netherlands, Sweden and Belgium hold significant positions with regard to certain indicators. Their long-standing research traditions and high level of competency in English could explain these positions,15 as well as a high level of investment in R&D. On the other hand, it should not be forgotten that, for some countries, having only one cardiology journal in the cardiovascular category of the JCR can prove to be a disadvantage when compared with other more highly represented countries, such as the United States (which produced 42 of the 75 journals in the category in 2007), the United Kingdom (with 11 journals), Germany (5 journals), the Netherlands (5 journals), Japan (3 journals), and Italy (2 journals). Spain is among those countries with only 1 cardiovascular journal in the JCR, Revista Española de Cardiología, whose impact has increased significantly in recent years16 and which came in 28th among the 78 journals in the category in 2008. Other countries with just one journal include France, Belgium, Canada, Switzerland, Russia, and Norway, although none of these can be found in the first quartile. However, it should be noted that Revista Española de Cardiología plays an important role in the international circulation of high-quality cardiological science: almost one third of articles by Spanish authors published in CCS-JCR journals can be found in this bilingual journal.
With regard to the citing of cardiological studies, the United States dominates with 49.7% of all citations, and the European Union amasses 43.9%. Spain holds 7th place among the EU-27, behind Germany, United Kingdom, Italy, Netherlands, France, and Sweden, and 11th in the world rankings, behind the United States, Canada, Japan and Australia. In the index of citations received per article, Spain comes 12th in Europe and 15th worldwide. Table 6 allows us to see the place held by Spanish cardiovascular research in Europe and the world, according to each of the indicators mentioned in this paper.
The predominance of the United States, garnering the highest percentage of citations and outperforming the EU-27, has also been seen in other biomedical categories, such as intensive-care medicine,15 clinical oncology,17 microbiology,18 and radiology.19 Conversely, a previous study which analysed worldwide contribution in cardiovascular medicine during the period 1995-2002 also showed a higher global output from the EU compared with the United States, although the average impact of the European articles was less than that of US articles.20 It is worth mentioning the bias found in the SCI-E database coverage, which favours US journals, as well as other factors affecting citations described in other studies.5,7 There is also the belief, on the part of some authors, that any study published in English and with only English citations will receive a higher level of scientific recognition, even though foreign language citations may be of a high quality and great scientific relevance.16
Furthermore, there is a pressure to publish as many articles as possible in many particular groups and nations. This can reduce the average number of citations received for articles by certain authors or groups, when compared with other authors or groups who publish only the most significant results.5,7,21
CONCLUSIONS
Despite the positive data expressed here, some reports and commentaries published in the scientific literature give cause for concern, in that they question the advantages of cardiovascular research given its negligible economic benefits when compared with research into other diseases.11 Promoting high-quality cardiology research in Europe should be an important goal, both for the European Society of Cardiology and national societies.22 To improve research and overcome the differences between countries, it would be necessary to push certain activities, including encouraging communication between researchers in order to establish multinational programmes, promoting English tuition in order to improve efficiency of communication, exploring in full the possibilities of funding from the EU, providing the necessary technology for young researchers lacking resources,23 and promoting adequate academic understanding of the merits of scientific publication. With regard to the cardiovascular field, it is necessary to promote economic support and resources in order to maintain adequate levels of research,12 strengthening and reinforcing research networks of excellence.23 Studies analysing the scientific activities of publications provide data which allows the creators and managers of research to evaluate the impact of their policies, adopting measures to correct identified weaknesses and reinforce strong points.21,24,25
Methodological Limitations
Among the limitations of this study, it is worth mentioning that only the production and impact of cardiological articles published in CCS-JCR category journals have been analysed, in spite of the fact that cardiologists also publish articles in journals from other categories, such as general and internal medicine, medical imaging, paediatrics, nephrology, etc. as well as multidisciplinary journals. On the other hand, numerous professionals from other specialities complement the professional exercise and research provided by cardiologists, thus improving production in terms of scientific results.12 However, calculation and analysis of journals specific to distinct biomedical fields is the routine method used for bibliometric studies in the SCI-E database, since this gives the most reliable picture of the research carried out in these fields, and this database has been widely used in previous studies.4,5,7,26 Another limitation is that the SCI-E database does not cover several national cardiological publications. However, it was decided that this database would best serve the needs of this study, since it involves the so-called "science mainstream" and allows us to identify and compare the contributions of every country in the world to this trend. The decision to select SCI-E as opposed to Medline, in spite of its wider biomedical coverage, was based on the fact that only the former allows the examination of citations and impact of the included publications.
ABBREVIATIONS
CCS: Cardiac and Cardiovascular Systems
JCR: Journal Citation Reports
GDP: Gross Domestic Product
SEE ARTICLE ON PAGES 1347-9
This study has been carried out thanks to a grant awarded by the Spanish Society of Cardiology.
Correspondence: Dr. R. Aleixandre Benavent.
Palacio Cerveró.
Pl. de Cisneros 4. 46003 Valencia. España.
E-mail: Rafael.Aleixandre@uv.es