What is a clinical trial?

Clinical trials are research investigations in which people volunteer to test new treatments, interventions or tests as a means to prevent, detect, treat or manage various diseases or medical conditions. Some investigations look at how people respond to a new intervention* and what side effects might occur. This helps to determine if a new intervention works, if it is safe, and if it is better than the interventions that are already available.

Clinical trials might also compare existing interventions, test new ways to use or combine existing interventions or observe how people respond to other factors that might affect their health (such as dietary changes).

The World Health Organization (WHO) definition for 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 trial interventions include but are not restricted to

  • experimental drugs
  • cells and other biological products
  • vaccines
  • medical devices
  • surgical and other medical treatments and procedures
  • psychotherapeutic and behavioural therapies
  • health service changes
  • preventive care strategies and
  • educational interventions.

Researchers may also conduct clinical trials to evaluate diagnostic or screening tests and new ways to detect and treat disease.

*The word 'intervention' will be used to refer to interventions, treatments and tests throughout this website.

Why do we need clinical trials?

Clinical trials are essential to the development of new interventions. For example, without clinical trials, we cannot properly determine whether new medicines developed in the laboratory or by using animal models are effective or safe, or whether a diagnostic test works properly in a clinical setting. This is because computer simulation and animal testing can only tell us so much about how a new treatment might work and are no substitute for testing in a living human body.

Clinical trials also permit testing and monitoring of the effect of an intervention on a large number of people to ensure that any improvement as a result of the intervention occurs for many people and is not just a random effect for a one person.

Most modern medical interventions are a direct result of clinical research. New interventions for most diseases and conditions — including cancer, heart disease, high blood pressure and asthma — have been developed through clinical research. Clinical trials often lead to new interventions becoming available that help people to live longer and to have less pain or disability.

Clinical trials can also help to improve health care services by raising standards of treatment. Doctors and hospital staff involved in clinical trials are continually trained to provide best practice patient care. Australian clinical trials are recognised internationally for including very high quality patient care.