Clinical Trials


The US National Institutes of Health (NIH) defines a clinical trial as "a research study in which one or more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes". In 2014, the NIH published a notice revising (NOT-OD-15-015) the definition of "clinical trials" The aim is to "to make the distinction between clinical trials and clinical research studies clearer and to enhance the precision of the information NIH collects, tracks, and reports on clinical trials" [2]. The World Health Organization (WHO) defines clinical trials as "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. Interventions include but are not restricted to drugs, cells and other biological products, surgical procedures, radiological procedures, devices, behavioural treatments, process-of-care changes, preventive care, etc."

Clinical trials are designed to answer specific biomedical questions about medical or behavioral interventions such as new medical devices, new treatments (drugs, novel vaccines, drugs, dietary,..), surgical procedures,...

Registration of clinical trial

The Declaration of Helsinki (DoH) states that "every research study involving human subjects must be registered in a publicly accessible database before recruitment of the first subject."

Registration of clinical trials need to be performed, according to the requirements of the International Committee of Medical Journal Editors (ICMJE), with any Primary Registry part of the WHO Registry Network or an ICMJE approved registry.

Clinical Trial Registries

The main clinical trial registries are:

  • ClinicalTrials.Gov is a registry and results database of clinical studies in humans. It is maintained by the United States National Library of Medicine (NLM) at the National Institutes of Health (NIH). ClinicalTrials.Gov is the largest registery for clinical trials worldwide. On April, 4th 2017, the registery lists 242,206 studies located in 198 countries.
  • The EU Clinical Trials Register provides a platform for free search of clinical trials in European Union member states.
  • Our BD4Cancer database provides a list of clinical trials registries.

References