title: Funding source and primary outcome changes in clinical trials registered on ClinicalTrials.gov are associated with the reporting of a statistically significant primary outcome: a cross-sectional study.
abstract: BACKGROUND
  We and others have shown a significant proportion of interventional trials registered on ClinicalTrials.gov have their primary outcomes altered after the listed study start and completion dates. The objectives of this study were to investigate whether changes made to primary outcomes are associated with the likelihood of reporting a statistically significant primary outcome on ClinicalTrials.gov.
  
  
  METHODS
  A cross-sectional analysis of all interventional clinical trials registered on ClinicalTrials.gov as of 20 November 2014 was performed. The main outcome was any change made to the initially listed primary outcome and the time of the change in relation to the trial start and end date.
  
  
  RESULTS
  13,238 completed interventional trials were registered with ClinicalTrials.gov that also had study results posted on the website. 2555 (19.3%) had one or more statistically significant primary outcomes. Statistical analysis showed that registration year, funding source and primary outcome change after trial completion were associated with reporting a statistically significant primary outcome .
  
  
  CONCLUSIONS
  Funding source and primary outcome change after trial completion are associated with a statistically significant primary outcome report on clinicaltrials.gov.
authors.affiliation: SVR Consulting, London, UK.
authors.forename: Sreeram V
authors.initials: SV
authors.lastname: Ramagopalan
authors.affiliation: Imperial College Medical School, London, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Skingsley
authors.affiliation: Medical Research Council Functional Genomics Unit and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Lahiru
authors.initials: L
authors.lastname: Handunnetthi
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Magnus
authors.affiliation: Department of Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Klingel
authors.affiliation: Medical Research Council Functional Genomics Unit and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Pakpoor
authors.affiliation: Department of Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Ben
authors.initials: B
authors.lastname: Goldacre
keywords: clinical trials; funding; primary outcome