Unique Trial Number

Unique trial number

Trial Registration:

Each clinical trial must have a unique trial number. This requirement is cited in a number of publications including:

  1. The Declaration of Helsinki of the World Medical Association (revised October 2013 Brazil) states: "Every research study involving human subjects must be registered in a publicly accessible database before recruitment of the first subject."
  2. The Research Governance Framework (England)link opens in a new page states it is the sponsor’s responsibility to ensure that:Appropriate arrangements are in place for the registration of trials.”
  3. The International Committee of Medical Journal Editors (ICMJE) stipulated that from July 1st 2005, "no trial will be considered for publication unless it is included on a clinical trials registry so it can be tracked from initial protocol through to publication."

The World Health Organisation (WHO) regards trial registration as the publication of an internationally agreed standard dataset about a clinical trial on a publicly accessible database managed by a registry conforming to WHO standards. The standard dataset is published by the WHO International Clinical Trials Registry Platform (ICTRP)link opens in a new page.

The International Standard Randomised Controlled Trial Number (ISRCTN)link opens in a new page is a registry and curated database containing the basic set of data items deemed essential to describe a study at inception, as per the requirements set out by the World Health Organisation (WHO) International Clinical Trials Registry Platform (ICTRP) and the International Committee of Medical Journal Editors (ICMJE) guidelines.

The NIHR Portfolio Database facilitates ISRCTN registration for eligible studies. Additional information can be found on ISRCTN registration on the Clinical Research Networklink opens in a new page.

Alternatively, trials may be registered at ClinicalTrials.govlink opens in a new page.

The EudraCT number is an additional mandatory reference number allocated by the European Medicines Agency (EMA) for CTIMPs authorised on or after 1 May 2004. (see EudraCT Number station). Further details are available from the EMAlink opens in a new page.

It is government policy in the UK to promote registration of clinical studies and public access to research findings affecting health and social care. 

For other randomised controlled trials and other forms of studies designed to assess the efficacy of healthcare interventions, it is still good practice to register the trial on a database such as ISRCTN. 

Future plans:

The Health Research Authority (HRA)link opens in a new page intends to make the Integrated Research Application System (IRAS)link opens in a new page project identifier available and visible on the creation of projects in IRAS. This will provide an additional reference number to complement those currently used to identify studies. The IRAS identifier will not replace other identifiers but the universal use of one identifier will help resolve issues in identifying studies across the different systems.

Further reading: