Letters Trial registration and publication

Don’t underestimate the extent of under-reporting

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f639 (Published 06 February 2013) Cite this as: BMJ 2013;346:f639
  1. Carl Heneghan, director1,
  2. Matthew Thompson, clinical reader1
  1. 1Centre for Evidence-Based Medicine, University of Oxford, Oxford OX2 6GG, UK
  1. carl.heneghan{at}phc.ox.ac.uk

Chalmers and colleagues state that under-reporting of research “leads to overestimates of the benefits of treatments and underestimates of their harmful effects.”1

The extent of the problem should not be underestimated. A 2010 study of 546 drug trials, conducted between 2000 and 2006, reported that only 66% had published their results. Rates of trial publication within 24 months of study completion ranged from 32% in industry funded trials to 56% in those funded by non-profit or non-federal organisations.2

The situation does not seem to have improved much since then. Analysis of trials listed on ClinicalTrials.gov found that only 46% of 677 trials completed by 2007 were published in a peer reviewed Medline listed biomedical journal within 30 months of trial completion.3 Mandatory reporting of trials seems to have made little difference. The overall rate of compliance with the mandatory reporting rate for 2009 trials listed on ClinicalTrials.gov within one year of completion is only 22%.4 A further study of ClinicalTrials.gov data from 2009 to 2010 reported that only 52% of 152 trials had associated publications within two years of posting.5

The size and problems associated with under-reporting of trials are substantial and continuing. Mandatory reporting has failed to resolve the matter, and finding a solution should be a priority for healthcare.


Cite this as: BMJ 2013;346:f639


  • Competing interests: None declared.