title: Cough as a symptom and a disease entity: scientometric analysis and density-equalizing calculations.
abstract: BACKGROUND
  Cough is a prominent symptom of many allergic diseases and a major health burden but there is little information available on the current state of research in this area.
  
  
  OBJECTIVE
  To analyze long-term developments in cough research and recent trends.
  
  
  METHODS
  We searched the Thomson Reuters Web of Science databases for cough-related items published between 1900 and 2007 and analyzed the results using scientometric methods and density-equalizing calculations.
  
  
  RESULTS
  We found 12 960 cough-related publications from 132 countries for the period studied. The most productive country was the United States of America (USA), followed by the United Kingdom (UK), France, Japan, Canada, and Germany. These 12 960 published items were cited 165 868 times. The average number of citations per item increased from 1976 to 1992, with peaks in 1977, 1979, 1981, 1984, 1989 and 1992. Each of these years was followed by a decrease in citation numbers. Bilateral and multilateral cooperation analysis using the radar chart technique showed a progressive increase in international co-authorship starting at the beginning of the 1990s, with a leading role by the USA and the UK.
  
  
  CONCLUSIONS
  We detected a marked increased in cough-related research starting in the 1990s. While the majority of data originates from the US, other countries have taken a leading position in terms of research quality (number of citations per item).
authors.affiliation: Otto-Heubner-Centre, Charité-Universitätsmedizin Berlin, Free University Berlin and Humboldt-University Berlin, Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Groneberg-Kloft
authors.forename: Q Thai
authors.initials: QT
authors.lastname: Dinh
authors.forename: C
authors.initials: C
authors.lastname: Scutaru
authors.forename: T
authors.initials: T
authors.lastname: Welte
authors.forename: A
authors.initials: A
authors.lastname: Fischer
authors.forename: K Fan
authors.initials: KF
authors.lastname: Chung
authors.forename: D
authors.initials: D
authors.lastname: Quarcoo
mesh_terms: D035843:Biomedical Research / Q000639:trends; D002170:Canada; D003371:Cough / Q000453:epidemiology*; D003627:Data Interpretation, Statistical; D016206:Databases, Bibliographic; D005602:France; D005858:Germany; D006801:Humans; D007391:International Cooperation; D007564:Japan; D008490:Medical Informatics; D011642:Publications; D006113:United Kingdom; D014481:United States