title: Using ClinicalTrials.gov to understand the state of clinical research in pulmonary, critical care, and sleep medicine.
abstract: BACKGROUND
  ClinicalTrials.gov is the largest trial registry in the world. Strengthened registration requirements, including federal mandates in 2007, have increased study representation. A systematic evaluation of all registered studies has been limited by the absence of an aggregate data set and specialty-specific search terms.
  
  
  OBJECTIVE
  We leveraged a newly transformed database containing annotated data from ClinicalTrials.gov to define the portfolio of interventional clinical research in pulmonary, critical care, and sleep medicine.
  
  
  METHODS
  Analysis was restricted to studies registered after September 2007 through September 2010 and defined as "interventional" (n = 40,970). A specialty-specific study data set (n = 2,226) was created using disease condition terms provided by data submitters and medical subject heading terms generated by a National Library of Medicine algorithm. Trial characteristics were extracted and summarized using descriptive statistics.
  
  
  RESULTS
  Pulmonary, critical care, and sleep medicine trials composed 5.4% of all interventional studies registered over the 3-year period. In contrast, oncology and cardiovascular disease composed 21.9 and 8.4% of trials, respectively. Within pulmonary trials, asthma and chronic obstructive pulmonary disease were the most studied conditions (27.4 and 21.8% of studies, respectively), and measures of lung function or safety were the most frequent primary outcomes. Nearly two-thirds of trials indicated enrollment of 100 patients or fewer, and a majority of studies were phase II or III trials. The single largest funding source (43.5%) was industry, and study characteristics varied by funding source.
  
  
  CONCLUSIONS
  We applied a novel approach to describe the portfolio of interventional clinical research in pulmonary medicine. Our results indicate a disparity between trial representation and the burden of respiratory disease. Resources should be targeted across the spectrum of pulmonary research to address this discrepancy.
authors.affiliation: 1 Duke University Medical Center, Durham, North Carolina; and.
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Todd
authors.forename: Kyle R
authors.initials: KR
authors.lastname: White
authors.forename: Karen
authors.initials: K
authors.lastname: Chiswell
authors.forename: Asba
authors.initials: A
authors.lastname: Tasneem
authors.forename: Scott M
authors.initials: SM
authors.lastname: Palmer
mesh_terms: D035843:Biomedical Research; D002986:Clinical Trials as Topic; D003422:Critical Care; D016208:Databases, Factual; D006801:Humans; D015272:Pulmonary Medicine; D012042:Registries; D056508:Sleep Medicine Specialty