title: Trial Registration at ClinicalTrials.gov between May and October 2005.
abstract: BACKGROUND
  Clinical trial registration allows interested parties to obtain information about ongoing and completed trials, but there are few data indicating the quality of the information provided during the registration process. We used information in the publicly available ClinicalTrials.gov database to describe patterns of trial registration before and after the implementation by journal editors of a new policy requiring registration as a prerequisite for publication.
  
  
  METHODS
  We reviewed ClinicalTrials.gov records to determine patterns of completion of the "Intervention Name" and "Primary Outcome Measure" data fields for trials registered on May 20 and October 11, 2005, and for trials registered during the interval between these two dates, inclusively.
  
  
  RESULTS
  During the interval studied, the number of registrations in ClinicalTrials.gov increased by 73 percent from 13,153 to 22,714. The percentage of interventional trials registered by industry with nonspecific Intervention Name entries (attributable to four drug companies) decreased from 10 percent to 2 percent; all other industry and nonindustry records contained specific entries in this field. Of the 2670 studies registered by industry between the two dates, 76 percent provided information in the Primary Outcome Measure field, although these entries varied markedly in their degree of specificity. In the remaining 24 percent of the records, this field was blank.
  
  
  CONCLUSIONS
  During the summer of 2005, there were large increases in the number of clinical trial registrations. Overall, the data contained in records were more complete in October than they were in May, but there still is room for substantial improvement.
authors.affiliation: Lister Hill National Center for Biomedical Communications, National Library of Medicine, National Institutes of Health, Bethesda, Md 20894, USA. dzarin@mail.nih.gov
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Zarin
authors.forename: Tony
authors.initials: T
authors.lastname: Tse
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Ide
mesh_terms: D002986:Clinical Trials as Topic / Q000331:legislation & jurisprudence; D019992:Databases as Topic / Q000592:standards / Q000706:statistics & numerical data / Q000639:trends*; D004345:Drug Industry; D035081:Editorial Policies; D006801:Humans; D009317:National Library of Medicine (U.S.); D017063:Outcome Assessment, Health Care; D010506:Periodicals as Topic; D012042:Registries / Q000592:standards; D014481:United States