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Non-publication and delayed publication of randomized trials on vaccines: survey

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g3058 (Published 16 May 2014) Cite this as: BMJ 2014;348:g3058
  1. Lamberto Manzoli, associate professor12,
  2. Maria Elena Flacco, resident physician13,
  3. Maddalena D’Addario, resident physician45,
  4. Lorenzo Capasso, PhD student12,
  5. Corrado De Vito, assistant professor6,
  6. Carolina Marzuillo, assistant professor6,
  7. Paolo Villari, professor6,
  8. John P A Ioannidis, professor78
  1. 1Department of Medicine and Aging Sciences, University of Chieti, Via dei Vestini 5 66013 Chieti, Italy
  2. 2CeSI Biotech, Via Colle dell’Ara, Chieti, Italy
  3. 3Local Health Unit of Pescara, Italy
  4. 4Division of Clinical Epidemiology and Biostatistics, Institute of Social and Preventive Medicine, University of Bern, Switzerland
  5. 5Division of International and Environmental Health, Institute of Social and Preventive Medicine, University of Bern, Switzerland
  6. 6Department of Public Health and Infectious Diseases, Sapienza University of Rome, Italy
  7. 7Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
  8. 8Department of Health Research and Policy, Stanford University School of Medicine, Stanford, CA, USA
  1. Correspondence to: L Manzoli lmanzoli{at}post.harvard.edu
  • Accepted 24 April 2014

Abstract

Objective To evaluate the extent of non-publication or delayed publication of registered randomized trials on vaccines, and to investigate potential determinants of delay to publication.

Design Survey.

Data sources Trials registry websites, Scopus, PubMed, Google.

Study selection Randomized controlled trials evaluating the safety or the efficacy or immunogenicity of human papillomavirus (HPV), pandemic A/H1N1 2009 influenza, and meningococcal, pneumococcal, and rotavirus vaccines that were registered in ClinicalTrials.gov, Current Controlled Trials, WHO International Clinical Trials Registry Platform, Clinical Study Register, or Indian, Australian-New Zealand, and Chinese trial registries in 2006-12. Electronic databases were searched up to February 2014 to identify published manuscripts containing trial results. These were reviewed and classified as positive, mixed, or negative. We also reviewed the results available in ClinicalTrials.gov.

Main outcome measures Publication status of trial results and time from completion to publication in peer reviewed journals.

Data synthesis Cox proportional hazards regression was used to evaluate potential predictors of publication delay.

Results We analysed 384 trials (85% sponsored by industry). Of 355 trials (404 758 participants) that were completed, 176 (n=151 379) had been published in peer reviewed journals. Another 42 trials (total sample 62 765) remained unpublished but reported results in ClinicalTrials.gov. The proportion of trials published 12, 24, 36, and 48 months after completion was 12%, 29%, 53%, and 73%, respectively. Including results posted in ClinicalTrials.gov, 48 months after study completion results were available for 82% of the trials and 90% of the participants. Delay to publication between non-industry and industry sponsored trials did not differ, but non-industry sponsored trials were 4.42-fold (P=0.008) more likely to report negative or mixed findings. Negative results were reported by only 2% of the published trials.

Conclusions Most vaccine trials are published eventually or the results posted in ClinicalTrials.gov, but delays to publication of several years are common. Actions should focus on the timely dissemination of data from vaccine trials to the public.

Footnotes

  • Contributors: All authors participated in the design, analysis, and interpretation of the study. LM, PV, and JPAI were involved in all phases of the study. JPAI and LM led the statistical analysis and assisted MD, LC, MEF, and CD in data extraction. MD, MEF, and CD carried out the methodological quality assessment. LM, MEF, and JPAI wrote the manuscript. LM is the guarantor for all data.

  • Funding: This study was not funded.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organization for the submitted work; no financial relationships with any organization that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Not required.

  • Data sharing: No additional data.

  • Transparency: The guarantor affirms that the manuscript is a honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

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