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).
Clinical trial interventions include but are not restricted to:
- experimental drugs
- cells and other biological products
- 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 page.
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.
How clinical trials work?
Researchers may first test new interventions in the laboratory and in animal studies. The most promising experimental interventions are then moved into clinical trials where they are tested in humans. During a clinical trial, more information is gathered about the effectiveness and safety of a new intervention.
In a clinical trial, the new intervention will usually be compared against something else, called a control. The control can be either a placebo (a substance containing no medication) or an established intervention that is already in use.
In Australia, clinical trials are governed by national ethics guidelines and codes of conduct. For further information on requirements, see the National Statement on Ethical Conduct in Human Research and the Australian Code for Responsible Conduct of Research .
Clinical trials of unapproved substances and devices also must comply with the requirements of the Therapeutic Goods Administration (TGA) and with international guidelines, as adopted by the TGA.
Who can be part of a clinical trial?
Due to the wide variety of trials taking place, almost anyone can take part in a clinical trial. Trials can involve people of all ages, from children to the elderly, and with all types and stages of a disease or condition. Taking part in a trial is completely voluntary and participants can withdraw at any time with no adverse effects on the quality of their medical treatment or relationship with their doctor.
Some trials need healthy participants to test the safety of new interventions or tests, particularly in early stage trials. In these trials, healthy participants can be compared with patient participants. They receive the same test, procedure or drug that the patient group receives and researchers can compare the effects and side effects of the new test, procedure or drug between the two groups.
Many trials need participants who have the disease or condition that the new intervention targets. Patient participants test the new intervention to see what effect it has on their disease or condition.
Why you might not be able to take part
All clinical trials have guidelines about who can take part. These guidelines are called inclusion and exclusion criteria. Criteria that must be met in order to allow someone to take part in a clinical trial are ‘inclusion criteria’; criteria that prevent someone taking part are ‘exclusion criteria’. The criteria may be based on age, gender, the type and stage of a disease or condition, previous treatment history and other medical conditions. Inclusion and exclusion criteria aim to ensure that the trial will produce useful and reliable results and contribute to the safe conduct of the study.
Sometimes, it is not possible for a volunteer to be involved in a particular trial. For example:
- some trials seek people with certain diseases and conditions, while others need healthy people
- the disease or condition may need to be at a particular stage
- participants may not be allowed to receive another treatment at the same time
- some trials need people of a certain age
- there may already be enough people in a particular category who have joined the trial.
Before participants join a trial, they may need to have tests (such as a blood test) to see if they can take part. These tests may also allow the researchers to know more about a person’s health before they start trial treatment, so that, at the end of the trial, they can tell if there has been an improvement. During the trial, participants are likely to have more tests to see whether the treatment is working.
Source: National Health and Medical Research Council