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01 November 2014 
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guidance notes

ISRCTN Guidance Notes

The following documentation provides information on how and when to use the ISRCTN assigned to your trial and how to cite your trial record.

How should the ISRCTN be used?

  • When quoting the ISRCTN, please make sure that no space is inserted between the ISRCTN and the actual number
  • Where practical, the ISRCTN should be used in all aspects of trial management and documentation. It should be referenced in all new material relating to the trial and used in future correspondence, reports and publications.
  • If the trial is registered within an existing specialist register, the ISRCTN should also be quoted in the other register. This will aid in de-duplications between registers.
  • The ISRCTN should be retained, even if there are alterations to the protocol, the investigators or the funding body
  • ISRCTNs that are taken out of use will not be re-allocated to another trial
  • The ISRCTN does not replace the trial acronym. Nor is the trial acronym a replacement for the ISRCTN. They should not be used interchangeably.

How to cite an ISRCTN trial record?

All ISRCTN records have digital object identifiers (DOIs).

DOIs issued by the organisation CrossRef are unique alphanumeric ID assigned to a digital object, such as an electronic journal, article, report, or thesis or a clinical trial record. A DOI serves as a stable, persistent link to the full-text of an electronic item on the internet. The journal or article website address can change over time but a DOI is permanent. DOIs are widely used by academic publishers for helping to ensure the permanence, discoverability and citability of scholarly content published on the web.

A trial ID such as the ISRCTN uniquely identifies a clinical trial. The DOI, made up of the ISRCTN 8 digits, will ensure that the web link to the trial ID can persistently be discovered and cited. Implementation of a DOI system is a vital step for the threaded publications initiative which puts trial registration with clinical trial registers such as the ISRCTN register at the top of transparent reporting. A DOI for a ISRCTN record will ensure that all publications and outcomes of a clinical trial are disseminated in a linked and threaded fashion.

To cite an ISRCTN trial record in the reference list of an article, please include all named authors, up to the first 3 before adding 'et al., eg:
Mendelow, AD (2006): Surgical Trial in Lobar Intracerebral Haemorrhage. Current Controlled Trials. Current Controlled Trials. http://dx.doi.org/10.1186/ISRCTN22153967

When to use the ISRCTN trial ID and the ISRCTN DOI?

If you simply wish to mention the trial reference, use the trial ID, eg: ISRCTN22153967
If you wish to mention the web address of the trial record, use the DOI, eg: http://dx.doi.org/10.1186/ISRCTN22153967

ISRCTN checklist for investigators

  • Record the ISRCTN on the master copies of all trial documentation (e.g. protocol, trial forms, patient leaflets, reports, etc.,)
  • Make arrangements to use the ISRCTN in publications, conference presentations, correspondence relevant to the trial and references to the trial (e.g. new grant applications)
  • If the trial is registered on a specialist trial register, inform the register co-ordinator of the ISRCTN
  • Notify funding bodies, other than that which assigned the ISRCTN, if they are co-funding the trial
  • Notify other sponsoring partners (e.g. companies supplying drugs or other materials to the trial, overseas co-operating or collaborative partners etc.,)

When/how to update a record

The ISRCTN Register does not insist on regular updates to a trial record but will regularly review the content and get in touch with the contact listed. If the trial end date has been altered or if your trial has evolved substantially since ISRCTN registration, please use the updating record page to contact CCT and have the record amended accordingly.


If you publish an article that is directly reporting on either the protocol or results of your trial, then it is always preferable to quote your ISRCTN in the manuscript. Many journals are now insisting on trial registration prior to manuscript submission so you may find that there is a specific rule for the journal you are submitting to. You do not need to inform CCT of the publication of your results, as the CCT Editorial Team should pick up on this as soon as your manuscript has been published and listed on PubMed. However, if your publication has not been added to the record two weeks after appearing in PubMed, please contact the CCT Editorial Team.

For any other questions on how to use the ISRCTN, please contact the CCT Editorial Team.

10 February 2014

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