title: Public availability of results of observational studies evaluating an intervention registered at ClinicalTrials.gov.
abstract: BACKGROUND
  Observational studies are essential for assessing safety. The aims of this study were to evaluate whether results of observational studies evaluating an intervention with safety outcome(s) registered at ClinicalTrials.gov were published and, if not, whether they were available through posting on ClinicalTrials.gov or the sponsor website.
  
  
  METHODS
  We identified a cohort of observational studies with safety outcome(s) registered on ClinicalTrials.gov after October 1, 2007, and completed between October 1, 2007, and December 31, 2011. We systematically searched PubMed for a publication, as well as ClinicalTrials.gov and the sponsor website for results. The main outcomes were the time to the first publication in journals and to the first public availability of the study results (i.e. published or posted on ClinicalTrials.gov or the sponsor website). For all studies with results publicly available, we evaluated the completeness of reporting (i.e. reported with the number of events per arm) of safety outcomes.
  
  
  RESULTS
  We identified 489 studies; 334 (68%) were partially or completely funded by industry. Results for only 189 (39%, i.e. 65% of the total target number of participants) were published at least 30 months after the study completion. When searching other data sources, we obtained the results for 53% (n = 158; i.e. 93% of the total target number of participants) of unpublished studies; 31% (n = 94) were posted on ClinicalTrials.gov and 21% (n = 64) on the sponsor website. As compared with non-industry-funded studies, industry-funded study results were less likely to be published but not less likely to be publicly available. Of the 242 studies with a primary outcome recorded as a safety issue, all these outcomes were adequately reported in 86% (114/133) when available in a publication, 91% (62/68) when available on ClinicalTrials.gov, and 80% (33/41) when available on the sponsor website.
  
  
  CONCLUSIONS
  Only 39% of observational studies evaluating an intervention with safety outcome(s) registered at ClinicalTrials.gov had their results published at least 30 months after study completion. The registration of these observational studies allowed searching other sources (results posted at ClinicalTrials.gov and sponsor website) and obtaining results for half of unpublished studies and 93% of the total target number of participants.
authors.affiliation: Centre d'Épidémiologie Clinique, Hôpital Hôtel Dieu, Assistance Publique des Hôpitaux de Paris, 1, Place du parvis Notre Dame, 75181, Paris, Cedex 4, France.|Paris Descartes University, Paris, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Baudart
authors.affiliation: Centre d'Épidémiologie Clinique, Hôpital Hôtel Dieu, Assistance Publique des Hôpitaux de Paris, 1, Place du parvis Notre Dame, 75181, Paris, Cedex 4, France.|Paris Descartes University, Paris, France.|METHODS Team, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, UMR 1153, INSERM, Paris, France.|French Cochrane Center, Paris, France.|Department of Epidemiology, Columbia University Mailman School of Public Health, New York, NY, USA.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ravaud
authors.affiliation: Centre d'Épidémiologie Clinique, Hôpital Hôtel Dieu, Assistance Publique des Hôpitaux de Paris, 1, Place du parvis Notre Dame, 75181, Paris, Cedex 4, France.|Paris Descartes University, Paris, France.|METHODS Team, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, UMR 1153, INSERM, Paris, France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Baron
authors.affiliation: Paris Descartes University, Paris, France.|METHODS Team, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, UMR 1153, INSERM, Paris, France.
authors.forename: Agnes
authors.initials: A
authors.lastname: Dechartres
authors.affiliation: Paris Descartes University, Paris, France.|METHODS Team, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, UMR 1153, INSERM, Paris, France.
authors.forename: Romana
authors.initials: R
authors.lastname: Haneef
authors.affiliation: Centre d'Épidémiologie Clinique, Hôpital Hôtel Dieu, Assistance Publique des Hôpitaux de Paris, 1, Place du parvis Notre Dame, 75181, Paris, Cedex 4, France. isabelle.boutron@htd.aphp.fr.|Paris Descartes University, Paris, France. isabelle.boutron@htd.aphp.fr.|METHODS Team, Centre of Research in Epidemiology and Statistics Sorbonne Paris Cité, UMR 1153, INSERM, Paris, France. isabelle.boutron@htd.aphp.fr.|French Cochrane Center, Paris, France. isabelle.boutron@htd.aphp.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Boutron
mesh_terms: D022126:Access to Information; D015982:Bias; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D016208:Databases, Factual / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D020407:Internet; D064887:Observational Studies as Topic / Q000706:statistics & numerical data*; D011642:Publications / Q000706:statistics & numerical data* / Q000600:supply & distribution*; D011643:Publishing / Q000592:standards / Q000706:statistics & numerical data*; D012042:Registries / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology
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