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A reminder: PLoS will reject unregistered trials

Last week, the PLoS Neglected Tropical Diseases editors rejected a clinical trial, without even sending it for peer review, because the trial had been initiated after July 1 2005 and yet the authors had failed to prospectively register it in a clinical trials registry.

We want to remind all authors again of our position on clinical trial registration, a position made explicit in our guidance to authors:

“PLoS supports the position of the International Committee of Medical Journal Editors (ICMJE) on trial registration. All trials initiated after 1 July 2005 must be registered prospectively in a publicly accessible registry (i.e., before patient recruitment has begun), or they will not be considered for publication. For trials initiated before 1 July 2005, all trials must be registered before submission to our journals. See the ICMJE faq on trial registration for further details. The WHO's list of approved registries is listed here.”

  1. One proposal that has been discussed amongst the editors here at PLoS is that, for unregistered clinical trials, we would encourage the authors to retrospectively register (eg at and then to add the results data for prespecified primary and secondary outcomes to the registry record. The website ( offers guidance to authors on how to do this, which has become mandatory for certain types of trials done after a specific cutoff date. However, even for older trials, depositing into the results database will ensure a trial’s key results are publicly accessible, and help to mitigate the effects of publication bias.

    Emma Veitch
    Senior Editor, PLoS Medicine
    Consulting Editor, PLoS ONE

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