Bibliometric study of clinical research articles published between 2005 and 2014, inclusive.

The inclusion criteria were as follows:

• 1)

  Articles indexed in Medline or Embase in which the affiliation (field for correspondence) indicates the author belongs to a Spanish dermatology and venereology institution or center. The affiliations of other authors were not considered as this information is not available in a consistent fashion in the databases analyzed and for all journals over the study period.

• 2)

  Articles with definitive publication date between 2005 and 2014, inclusive

• 3)

  Articles that met the following 3 criteria to be considered as clinical research.8 a) Studies performed in patients, individuals, health systems, or articles based on patients. This includes study of samples obtained from patients and healthy individuals, such as biopsies, dermoscopic images, laboratory measurements, etc. b) Studies answering a research question that can be posed in clinical practice, with the aim of resolving practical problems concerning patient management, including investigation of the etiology, diagnosis, prognosis, treatment, prevention, and prevalence of diseases and investigation of the economics of health systems. We included systematic reviews of these fields. c) Studies with level of evidence≤4 according to the Centre for Evidence-Based Medicine (CEBM) (Oxford) classification.9 That is, case reports and publications based on expert opinion without explicit evaluation methodology (which would make them systematic reviews), or those based on physiology, laboratory research, or basic science were excluded.9

To assign the level of evidence, an investigator (AML) reviewed the title and abstract of all articles included, and if the information was not sufficient to determine the level of evidence, the full text was inspected. If doubts about the level of evidence persisted after review of the full text, the articles were reviewed by another investigator (IGD or MD), and the level of evidence was assigned according to a consensus decision of the two.

The exclusion criteria were as follows:

• 1)

  Principally nondermatological topics of the article

• 2)

  Articles without a definitive publication date (Epub ahead of print)

The main variables of interest are grouped according to whether the variables were quantitative, topical, or qualitative.

Quantitative indicators included the number of articles of clinical research/articles published; number of articles/journal and rate of annual growth, defined as (number of articles selected per year-number of articles in previous year) divided by number of articles selected in the year.

The topic objective of the research articles was assessed by absolute frequency of repetition of words referring to dermatological diseases. Three sources of information were analyzed separately: title, keywords provided by the author, and keywords.

The qualitative indicator used was level of scientific evidence corresponding to each article according to the CEBM classification.

Articles were retrieved with the Scopus database. Scopus was preferred to other alternatives as the database for searches because it includes all documents indexed in Medline and Embase and because information on citations to each document can be extracted.

The date of the search was November 6, 2015. The search strategy was as follows: (AFFILCOUNTRY (spain OR espana OR spanien OR espagne OR espanha) AND AFFILORG (dermat*)) AND PUBYEAR > 2004 AND PUBYEAR < 2015

The search returned 8617 articles, of which 12.81% (1104 articles) met the inclusion criteria. The reasons for exclusion of articles are shown in Figure 1. The main reason for exclusion was not reaching minimum required level of scientific evidence according to the CEBM, 5805 articles (67.37%).

Figure 1.

Schematic of flow of articles included in and excluded from the study.

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The journal with the largest number of published articles was Actas Dermatosifiliográficas, which accounted for 29.53% (326 articles). The 10 journals with the largest number of articles are shown in Figure 2. The annual rate of growth of scientific output is shown in Figure 3. The year with greatest growth was 2014, with a rate of 23.8%.

Figure 2.

Ten journals with most number of publications.

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Figure 3.

Percentage annual growth in the study period.

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The dermatological diseases for which most articles were published were melanoma, with 134 articles (12.13%), psoriasis with 120 (10.86%), nonmelanoma skin cancer with 125 (11.32%), and eczema/dermatitis with 86 (7.79%). Table 1 shows the frequency of these terms. With respect to article topics with most number of bibliographic citations, melanoma was once again the most frequent topic (Table 1).

When the articles were classified according to the level of evidence of the CEBM, we found that 93.39% (1031 articles) had level of evidence 4, that is, they were case reports or publications based on expert opinion without an explicit assessment, or based on physiology, laboratory research, or basic science. The classification of articles is reflected in Table 2.

We present a bibliometric study in terms of output, topic, and level of scientific evidence of Spanish dermatology centers or institutions across a broad period with the inclusion of all articles included in the main databases.

In the study period, we see a notable overall scientific output. However, articles that meet the criteria to be considered as clinical research only represent a small percentage of the total. The main reason for exclusion of studies was failure to attain a level of scientific evidence of 4 or less according to the CEBM classification. This suggests that most of the publications are primarily reports of single isolated cases or, alternatively, publications based on expert opinion without an explicit methodology for assessment. Aranegui et al.,8 in a previous study of publications in 2008, showed that the level of scientific evidence of articles published by Spanish dermatologist was lower than that of other countries such as France or the United Kingdom.

The journal with the most number of articles was Actas Dermatosifiliográficas, the journal of the Spanish Academy of Dermatology and Venereology (abbreviated in Spanish as AEDV). This might be explained by the fact that Spanish dermatologists are more familiar with this journal and also because it is possible to publish in Spanish. Furthermore, access to this journal is free for academics and almost 97% of practicing dermatologists in Spain are affiliated to the institution.10 The time period for the study was chosen taking into account when Actas Dermatosifiliográficas became fully indexed on the assumption that a large number of articles by Spanish centers would be published in this journal.

With regards the rate of annual growth, we see a clear trend towards progressive growth in the number of articles published, and positive increases during several consecutive years followed by discrete percentage decreases.

The skin diseases with the most number of corresponding publications are in line with data from other studies with different designs.11,12 Skin cancers, with melanoma at the head, are the topic with most number of publications. Melanoma is a skin disease with increasing incidence in which important progress has been made in recent years with the incorporation of new molecular targets and therapeutic options.13 It is also one of the main causes of death in young subjects, and so has substantial media coverage.14 The above factors are probably responsible for the large number of publications on this process. The next skin disease on the list is psoriasis, which is also one of the diseases that has undergone a therapeutic revolution in recent decades and which also represents a systemic inflammatory disease with a high prevalence of multiple physical and psychological comorbidities.15 Nonmelanoma skin cancer, given its frequency and morbidity and mortality in our population, and contact dermatitis, probably due to the support from very active working group in Spain, complete the ranking of diseases with most number of publications.

The skin diseases present in the most cited number of articles correspond to the diseases with the most number of articles published.

On analysis of the level of scientific evidence of the articles of clinical research included, it is noteworthy that most have a level of evidence of 4. This group includes case series and cross-sectional studies. These types of studies may be more numerous because of the easier design and conduct compared with other studies. However, a recent study assessed the scientific impact and quality of articles published in dermatology anywhere in the world found that countries from northern Europe such as Norway and Sweden have a lower overall number of publications but a high level of methodological quality with high scientific impact.16

The results of this study should be considered in light of certain limitations. First, the criterion for attributing a scientific publication to a Spanish dermatology institution according to the affiliation of the corresponding author means that studies in which dermatologists who work or collaborate in studies directed by non-dermatological institutions would not be included. Therefore some national and international publications in which Spanish dermatologists have participated might not have been included. We chose this criterion because indexing of the affiliations of authors in the bibliographic database would provide more complete information, but it is not homogeneous over time and cannot be used to establish temporal comparisons. Second, the study period analyzed ranged from 2005 to 2014, inclusive. This range was not larger because regular indexing of the main Spanish journal of dermatology and venereology, Actas Dermatosifiliográficas, did not begin until 2005.