'Public registry'

A ‘public registry’ is defined as any register on the WHO list of primary registries or the ICMJE list of registries.

Recognised public registries include:

Imperial College strives to maintain the highest standard of research integrity from ethics applications (HRA, REC, ICREC and SETREC) to reporting of trial results. Imperial College considers trial transparency to be an important part of research integrity. The registration and reporting of clinical trials and results on a public database is critical as it becomes part of the public domain. Medical professionals, policy-makers and patients rely on published evidence to make health decisions.

It is a best practice expectation that all research should be registered in a publicly accessible database. However, for clinical trials, it is a condition of a favourable ethical opinion to do so. Since September 2013, the registration of clinical trials has been a formal condition of NHS Research Ethics Committee (REC) approval, in line with researcher and sponsor duties as set out by the WHO, current Declaration of Helsinki and the Research Governance Framework. EU legislation also requires that clinical trials of investigational medicinal products (CTIMPs) are entered in a public register (with limited exemptions for healthy volunteer studies). Registration should occur before the first participant is recruited. 

The International Committee of Medical Journal Editors (ICMJE) considers clinical trials for publication only if registered in an appropriate registry.

Any study that is registered on a public database must report its results on that database within one year of study completion (or six months for paediatric studies). 

Clinical trial registration and results reporting helps to prevent selective publication and selective reporting of research outcomes, to prevent unnecessary duplication of research effort, and to help patients and the public know what trials are planned or ongoing. When registering, you will need to pre-specify all outcomes that will be measured. If you have studies that are past due for results reporting, the RGIT will be unable to issue sponsorship for future studies until the outstanding issues have been resolved.

Clinical trials are defined as all studies which fall into the first four categories of question two on the Integrated Research Approval System (IRAS) filter page. These are:

     • Clinical trial of an investigational medicinal product
     • Clinical investigation or other study of a medical device
     • Combined trial of an investigational medicinal product and an Investigational medical device
     • Other clinical trial to study a novel intervention or randomised clinical trial to compare interventions in clinical practice

Examples of recognised public registries


International Standard Randomised Controlled Trial Number (ISRCTN) Registry is a publicly accessible clinical trial database that accepts all research studies; both prospective and retrospective registrations are accepted. It is officially recognised by the World Health Organisation (WHO) and the International Committee of Medical Journal Editors (ICMJE) as a primary clinical trials registry.


ClinicalTrials.gov is a publicly accessible database that accepts prospective and retrospective registration of medical studies in human volunteers. It is free to register and accepts any trial that meets the ICMJE definition of a clinical trial.


EudraCT (European Union Drug Regulating Authorities Clinical Trials) is the European Clinical Trials Database of all CTIMPs with at least one site in the European Union (predominantly for CTIMPS started prior to January 1, 2021). CTIMPS beginning on or after January 1, 2021, will only need to apply for a EudraCT number, but not report results on EudraCT.

Partnership between HRA and ISRCTN

Starting from January 2022, the HRA (Health Research Authority) will automatically register all clinical trials of investigational medicinal products (CTIMPs) with the ISRCTN registry, at no further cost to the sponsors or researchers. Imperial sponsored non-CTIMP studies will have the option to register on either ISRCTN or ClinicalTrials.gov depending on study team preference and funding.

This service, designed to streamline the reporting requirements for researchers, is also aligned with the HRA’s Make it Public strategy which aims to ensure research transparency across the UK. More details regarding this partnership can be found in the HRA’s Research Transparency Annual Report (2021), and the FAQ list prepared by the HRA.