title: Asthma research and randomized controlled trials: a remarkable phenomenon.
abstract: BACKGROUND
  Time trends in the number of publications of randomized controlled trials (RCTs) in asthma research have never been evaluated.
  
  
  METHODS
  A PubMed database scan was made to identify publications in asthma research per year since 1990 until 1 January 2010, using the term 'asthma'. The total number of publications was ascertained, as was the number when restricting the search strategy to RCTs only.
  
  
  RESULTS
  The total number of publications in asthma research increased from 2240 per year in 1990 to 5601 per year in 2009. The number of publications of RCTs in asthma research was 198 per year in 1990 and 233 per year in 2009.
  
  
  CONCLUSIONS
  The remarkable phenomenon of an almost unchanged number of publications of RCTs in asthma research per year in the period 1990-2009 may be explained by criticism to RCTs in asthma research.
  
  
  CONCLUSIONS
  Despite an increase in total publications of asthma research, time trends in the number of publications of RCTs in asthma research per year show an almost unchanged number in the period 1990-2009. Evidence-based medicine within the field of asthma still faces many challenges.
authors.affiliation: Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands. e.hafkamp@erasmusmc.nl
authors.forename: Esther
authors.initials: E
authors.lastname: Hafkamp-de Groen
authors.forename: Hein
authors.initials: H
authors.lastname: Raat
mesh_terms: D001249:Asthma; D035843:Biomedical Research / Q000639:trends*; D006801:Humans; D010506:Periodicals as Topic; D016032:Randomized Controlled Trials as Topic / Q000639:trends*