International Standard Randomised Controlled Trial Number: what is it and how will it help systematic reviewers?

Objective

To describe the new international numbering system for randomised controlled trials and to explore how it will be useful to people doing systematic reviews.

Background, methods and results

A major task that continues to confront the medical scientific community is to recognise what we know and what we don't know. In the context of RCTs, this means having a clear idea of what trials have been done and what they found, as well as what trials are planned and on going. This information is crucial for those planning trials (funders and trialists) as well as for those making clinical decisions (patients and clinicians). Much of the confusion in this area stems from the fact that each trial can generate many reports. The Olanzapine systematic review, for example, found 162 reports of 15 trials [1]. The International Standard Randomised Controlled Trial Number (ISRCTN) has been established to tackle this problem and to encourage prospective registration of trials.

Prospective registration should help to prevent publication bias and duplication of research, encourage collaboration, and inform potential trial participants. Growth in prospective registration, following legislation in some countries, such as the USA, accentuates the need to distinguish between different, but similar, trials. A working group including the (UK) Medical Research Council (MRC), UK Cochrane Centre, trialists, consumers, and the pharmaceutical industry has developed a unique identification system of International Standard Randomised Controlled Trial Numbers (ISRCTN). This should simplify trial identification and allow tracking of all publications/reports resulting from each trial.

The eight figure number is now being assigned to planned, on going, and completed trials. We hope that it will soon become a requirement for funding and ethical approval of trials and for publication of the results in journals. Systematic reviewers will be able to apply the number to trials, helping them and their readers to distinguish a trial from its several published and unpublished reports. The ISRCTN scheme will also help to create study based registers with links to the bibliographic records.

Conclusion

This presentation will describe the numbering scheme, explain plans for its use by ethics committees, funding bodies, and journals, and expand on its usefulness to those doing systematic reviews.

References

1. Duggan L, Fenton M, Dardennes RM, El-Dosoky A, Indran S: Olazapine for schizophrenia (Cochrane Review).

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