Trial registration
Thorough and transparent reporting of clinical trials is particularly important. Their results underpin many clinical policies and funding decisions about treatments, and it is vital that their findings are robust and reliable.
To ensure that all trial registries include the same kind of information the World Health Organisation has developed a minimum dataset and a web portal that provides links to the major national and international trial registries.
The journals on the International Committee of Medical Journal Editors (ICMJE) now refuse to consider papers reporting unregistered trials and the committee encourages all biomedical journals to do the same.
BMJ policy
In accordance with the ICMJE Recommendations, BMJ will not consider reports of clinical trials unless they were registered prospectively before recruitment of any participants. This applies to trials which commenced after 1 July 2005; for older trials retrospective registration will be acceptable, but only if completed before submission of the manuscript to the journal.
Eligible trials have been defined by ICMJE since 1 July 2008 as “where human participants are prospectively assigned to one or more health-related interventions [including health services and behavioural interventions] to evaluate the effects on health outcomes”, and before that were defined more narrowly as trials “where human participants are prospectively assigned to investigate the cause and effect relationship between a medical intervention and health outcome”.
This means that:
- Trials randomising human participants to investigate the cause and effect relationship between a medical intervention and a health outcome that commenced before 1 July 2005 can be registered retrospectively, but this must be done before submission.
- Trials randomising human participants to investigate the cause and effect relationship between a medical intervention and a health outcome that commenced after 1 July 2005 must have been registered prospectively (i.e. before enrolment of any participant).
- Trials randomising human participants or groups of humans to one or more health-related interventions (including health services and behavioural interventions) to evaluate the effects on health outcomes and that commenced after 1 July 2008 must have been registered prospectively (i.e. before enrolment of any participants).
Clinical trial protocols
BMJ requires authors of clinical trials submitted as research articles to upload a protocol for their study as a supplementary file. This protocol will be published alongside other materials if the article is accepted. For guidance on how to write a study protocol, please see our Before you submit section on BMJ Author Hub.