Frequently Asked Questions

Frequently Asked Questions

● What is a clinical trial?

For the purposes of registration, a clinical trial is any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes. Clinical trials may also be referred to as interventional trials. Interventions include but are not restricted to drugs, cells and other biological products, surgical procedures, radiologic procedures, devices, behavioural treatments, process-of-care changes, preventive care, etc. This definition includes Phase I to Phase IV trials.

● Which trials should be registered?

All clinical trials should be registered. Thus, early and late trials, trials of marketed or non-marketed products, randomized or non-randomized trials -- all should be registered.

● What is the difference between a clinical trials register and a clinical trials registry?

A clinical trials register is the formal record of an internationally agreed minimum amount of information about a clinical trial. This record is usually stored in and managed using a database. A clinical trials registry is the entity that houses the register, and is responsible for ensuring the completeness and accuracy of the information it contains, and that the registered information is used to inform health care decision making. A clinical trials registry is more than its database.

● Why register clinical trials?

The registration of all interventional trials is considered to be a scientific, ethical and moral responsibility because:

  • There is a need to ensure that decisions about health care are informed by all of the available evidence.
  • It is difficult to make informed decisions if publication bias and selective reporting are present.
  • The Declaration of Helsinki states that "Every clinical trial must be registered in a publicly accessible database before recruitment of the first subject".
  • Improving awareness of similar or identical trials will make it possible for researchers and funding agencies to avoid unnecessary duplication.
  • Describing clinical trials in progress can make it easier to identify gaps in clinical trials research.
  • Making researchers and potential participants aware of recruiting trials may facilitate recruitment.
  • Enabling researchers and health care practitioners to identify trials in which they may have an interest could result in more effective collaboration among researchers. The type of collaboration may include prospective meta-analysis.
  • Registries checking data as part of the registration process may lead to improvements in the quality of clinical trials by making it possible to identify potential problems (such as problematic randomization methods) early in the research process.

● Who is responsible for registering a trial?

An appropriate representative of the trial’s primary Sponsor. The Responsible Registrant is responsible for ensuring that the trial is properly registered. The primary Sponsor may or may not be the primary funder. The responsible registrant should make every reasonable effort to ensure that a trial is registered once and only once in any one register, and that the trial is registered in the fewest number of registers necessary to meet applicable regulations.

● When should trials be registered?

Trials should be registered before the first participant is recruited.

● Can I register with the WHO ICTRP?

No, WHO does not maintain its own registry so you cannot register your trial directly with WHO ICTRP.

● What information needs to be registered?

The minimum information that must be registered is specified in the WHO Trial Registration Data Set. Individual registers may request more information than this.

● Are there software or hardware specifications that should be followed for building a trial registry?

Yes, please contact WHO ICTRP.

● How many times should a trial be registered?

To meet WHO requirements for transparency and publication it is only necessary for your trial to be to registered once, in either a Primary Registry or an ICMJE approved registry.

● How do I cite a record on a clinical trials register?

Please read this document ( 

● When to cite a record on a clinical trials register?

The registry record will be the only publicly available document on a trial until results from the trial are published. Some examples of situations when studies might be quoted are:

  • When a manuscript reporting the results of the trial is published or otherwise reported
  • When a manuscript reporting methodological issues relating to a particular trial are published or otherwise reported
  • In protocols to systematic reviews, or in completed systematic reviews (e.g. when a list of ongoing trials are included)
  • In protocols to prospective meta-analyses, which will list the ongoing trials to be included
  • In any manuscript when reference to an ongoing or unpublished (or even published) trial might be relevant

● What is trial registration?

WHO regards trial registration as the publication of an internationally-agreed set of information about the design, conduct and administration of clinical trials. These details are published on a publicly-accessible website managed by a registry conforming to WHO standards.

What is the ICTRP?

The ICTRP is a global initiative that aims to make information about all clinical trials involving humans publicly available. It also aims to:

  • To improve the comprehensiveness, completeness and accuracy of registered clinical trial data
  • To communicate and raise awareness of the need to register clinical trials
  • To ensure the accessibility of registered data
  • To build capacity for clinical trial registration
  • To encourage the utilization of registered data
  • To ensure the sustainability of the ICTRP
ITMCTR BJ-ICP:07032215-5 Tip: IE8 is recommended Use the system with widescreen display resolution above