title: Scientific research in obstructive sleep apnea syndrome: bibliometric analysis in SCOPUS, 1991-2012.
abstract: OBJECTIVE
  The research in obstructive sleep apnea (OSA) may be beneficial from the collaboration between countries and researchers. In this study, we aimed to analyze the scientific research on OSA from 1991 to 2012 and to evaluate the collaboration networks between countries.
  
  
  METHODS
  We conducted a bibliometric study in the SCOPUS database. The systematic search was limited to "articles" published from 1991 to 2012. Articles are results of original research; we evaluated the following criteria: number of countries represented, number of authors, number of citations, and journal names. We determined which countries were the most productive (more articles published) and the number of collaborations between these countries. The probability of citation was evaluated using adjusted odds ratios in a logistic regression analysis.
  
  
  RESULTS
  We found a total of 6,896 OSA-related articles that had been published in 1,422 journals, 50 % of these articles were concentrated in 41 journals. Of the 74 different countries associated with these articles, the USA had the highest involvement with 23.8 % of all articles published. The probability of citation increased by 1.23 times for each additional author, and by 2.23 times for each additional country represented; these findings were independent of time since publication, journal, or the country of the author.
  
  
  CONCLUSIONS
  Scientific production on OSA is increasing with limited international collaboration. The country with the greatest production in this period (1991-2012) was the USA, which concentrated the international collaboration network on OSA. We recommended that articles should be produced with international collaboration to improve the quantity of scientific publications and their chances of publication in high impact journals.
authors.affiliation: Instituto Nacional de Salud, Lima, Peru, huamani_ca@hotmail.com.
authors.forename: Charles
authors.initials: C
authors.lastname: Huamaní
authors.forename: Jorge
authors.initials: J
authors.lastname: Rey de Castro
authors.forename: Gregorio
authors.initials: G
authors.lastname: González-Alcaide
authors.forename: Daniel Ninello
authors.initials: DN
authors.lastname: Polesel
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Monica Levy
authors.initials: ML
authors.lastname: Andersen
mesh_terms: D015706:Bibliometrics; D016206:Databases, Bibliographic; D006801:Humans; D007391:International Cooperation; D011643:Publishing; D012106:Research; D020181:Sleep Apnea, Obstructive