title: Association between trial registration and positive study findings: cross sectional study (Epidemiological Study of Randomized Trials-ESORT).
abstract: ObjectiveTo assess whether randomised controlled trials (RCTs) that were registered were less likely to report positive study findings compared with RCTs that were not registered and whether the association varied by funding source.DesignCross sectional study.Study sampleAll primary RCTs published in December 2012 and indexed in PubMed by November 2013. Trial registration was determined based on the report of a trial registration number in published RCTs or the identification of the trial in a search of trial registries. Trials were separated into prospectively and retrospectively registered studies.Main outcome measureAssociation between trial registration and positive study findings.Results1122 eligible RCTs were identified, of which 593 (52.9%) were registered and 529 (47.1%) were not registered. Overall, registration was marginally associated with positive study findings (adjusted risk ratio 0.87, 95% confidence interval 0.78 to 0.98), even with stratification as prospectively and retrospectively registered trials (0.87, 0.74 to 1.03 and 0.88, 0.78 to 1.00, respectively). The interaction term between overall registration and funding source was marginally statistically significant and relative risk estimates were imprecise (0.75, 0.63 to 0.89 for non-industry funded and 1.03, 0.79 to 1.36 for industry funded, P interaction=0.046). Furthermore, a statistically significant interaction was not maintained in sensitivity analyses. Within each stratum of funding source, relative risk estimates were also imprecise for the association between positive study findings and prospective and retrospective registration.ConclusionAmong published RCTs, there was little evidence of a difference in positive study findings between registered and non-registered clinical trials, even with stratification by timing of registration. Relative risk estimates were imprecise in subgroups of non-industry and industry funded trials.
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK ayodele.odutayo@bnc.ox.ac.uk.|Applied Health Research Centre (AHRC), Li Ka Shing Knowledge Institute of St Michael's Hospital, Toronto, ON, Canada.
authors.forename: Ayodele
authors.initials: A
authors.lastname: Odutayo
authors.affiliation: Faculty of Medicine, Harvard University, Boston, MA, USA.
authors.forename: Connor A
authors.initials: CA
authors.lastname: Emdin
authors.affiliation: Department of Economics, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Hsiao
authors.affiliation: Faculty of Medicine, Harvard University, Boston, MA, USA.
authors.forename: Mubeen
authors.initials: M
authors.lastname: Shakir
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Bethan
authors.initials: B
authors.lastname: Copsey
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Dutton
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Virginia
authors.initials: V
authors.lastname: Chiocchia
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Schlussel
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Dutton
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Corran
authors.initials: C
authors.lastname: Roberts
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
authors.affiliation: Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.
authors.forename: Sally
authors.initials: S
authors.lastname: Hopewell
mesh_terms: D003430:Cross-Sectional Studies; D005376:Financial Management; D005381:Financing, Organized; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000191:economics / Q000379:methods*; D012042:Registries; D012306:Risk