The extent of underreporting should not be underestimated
16 January 2013
The editorial of Chalmers et al highlights the fact that under-reporting of research has serious consequences and ‘leads to overestimates of the benefits of treatments and underestimates of their harmful effects.’ 
The extent of the problem should not to be underestimated. A study of 546 drug trials, conducted between 2000 and 2006, reported 66% had published their results. Rates of trial publication within 24 months of study completion ranged from 32% among industry-funded trials, to 56% among nonprofit or nonfederal organization–funded trials. 
The situation does not seem to have improved much since then. Analysis of trials listed on Clinical Trials.Gov, found that of 677 trials completed by 2007 only 46% were published in a peer-reviewed, Medline-listed biomedical journal within 30 months of trial completion  Mandatory reporting of trials appears to have made little difference. The overall rate of compliance with the mandatory reporting rate for 2009 trials listed on Clinical Trials.gov within one year following completion is only 22%.  A further study of clinical trials.gov data between 2009 and 2010 reported that only 52% of 152 trials had associated publications within 2 years after posting. 
The size and issues associated with under-reporting of trials problem are substantial and continuing. Mandatory reporting has failed to resolve the issue and finding a solution should be a priority for healthcare.
1. Chalmers I, GLasziou P, Godlee F. All trials must be registered and the results published. BMJ. 2013; 346:f105
2. Prayle A, Hurley M & Smyth AR. Compliance with mandatory reporting of clinical trials results on ClinicalTrials.gov: cross sectional analysis. BMJ 2012; 344:d7373
3. Deborah A. Zarin, Tony Tse, Rebecca J. Williams, Robert M. Califf, and Nicholas C. Ide. The ClinicalTrials.gov Results Database — Update and Key Issues. N Engl J Med 2011; 364:852-860March 3,
4. Ross JS, Tse T, Zarin DA, Xu H, Zhou L, Krumholz HM. Publication of NIH funded trials registered in ClinicalTrials.gov: cross sectional analysis. BMJ. 2012 Jan 3;344:d7292.
5. Bourgeois FT, Murthy S, Mandl KD. Outcome reporting among drug trials registered in ClinicalTrials.gov. Ann Intern Med. 2010 Aug 3;153(3):158-66.
Carl Heneghan and Matthew Thompson
Centre for Evidence-Based Medicine
University of Oxford
Competing interests: None declared
University of Oxford, University of Oxford
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