Clinical trials


    Clinical trials are a type of research that studies new tests and treatments and evaluates their effects on human health outcomes. People volunteer to take part in clinical trials to test medical interventions including drugs, cells and other biological products, surgical procedures, radiological procedures, devices, behavioural treatments and preventive care.

    Clinical trials are carefully designed, reviewed and completed, and need to be approved before they can start. People of all ages can take part in clinical trials, including children.

    There are 4 phases of biomedical clinical trials:

    • Phase I studies usually test new drugs for the first time in a small group of people to evaluate a safe dosage range and identify side effects.
    • Phase II studies test treatments that have been found to be safe in phase I but now need a larger group of human subjects to monitor for any adverse effects.
    • Phase III studies are conducted on larger populations and in different regions and countries, and are often the step right before a new treatment is approved.
    • Phase IV studies take place after country approval and there is a need for further testing in a wide population over a longer timeframe.


    WHO Response

    Clinical trials usually involve participants from more than one medical or research institution, and often more than one country. As each country has its own requirements for clinical trials research it is possible that single trials could be included on more than one registry, and hence appear on more than one registry database. However, data on various clinical trial registries varies.

    WHO’s International Clinical Trials Registry Platform (ICTRP) links clinical trials registers globally in order to ensure a single point of access and the unambiguous identification of trials with a view to enhancing access to information by patients, families, patient groups and others.

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

    • improve the comprehensiveness, completeness and accuracy of registered clinical trial data;
    • communicate and raise awareness of the need to register clinical trials;
    • ensure the accessibility of registered data;
    • build capacity for clinical trial registration;
    • encourage the utilization of registered data; and
    • ensure the sustainability of the ICTRP.



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