What are clinical trials?
Clinical trials are research studies that are carried out on humans. Clinical trials test whether new treatments are safe and effective.
The new treatment might be a new medicine, vaccine, or medical device. It may also be new lifestyle advice or a change to the health service.
Clinical trials can involve both healthy people and people with a medical condition.
Clinical trial and research ethics
A human research ethics committee must agree that a clinical trial is ethical before it can go ahead.
The ethics committee has a range of members that include:
- at least two members of the public
- a person who performs pastoral care in the community
- a lawyer
- people with professional caring experience, such as a nurse or allied health professional
In Australia, people must understand all the facts about a clinical trial before they can agree to take part. This is known as informed consent.
Why are clinical trials needed?
Clinical trials allow researchers to find out whether a new test or treatment is both safe and effective (works) in humans.
Before a clinical trial begins, tests will have already happened in the laboratory or in animal models. Clinical trials check that the positive results seen in these tests also occur in humans.
It also allows researchers to find out which people will benefit most from a new test or treatment.
Most new medical treatments and tests are a result of clinical trials.
Clinical trials lead to new tests, treatments and devices that help people to better manage their health conditions.
Phases of clinical trials
Clinical trials of new medicines usually take place in phases. These start with small numbers of people to check that the medicine is both safe and effective.
- Phase I clinical trials are the first trials to happen in humans. Usually this involves giving a group of 20 to 80 healthy volunteers the medicine to check that it‘s safe. Phase I clinical trials usually happen in centres that are specially set up to monitor the participants.
- Phase II clinical trials are often the first trials in people with the disease or condition of interest. The new medicine might be given to a few hundred people to check that it is safe and works.
- Phase III clinical trials involve giving a larger group of people (a few hundred to a few thousand) the new medicine. Often the new medicine is compared to other standard tests or treatments for a specific disease. Phase III trials only happen if good results are seen in Phase II.
- Phase IV clinical trials happen after the new test or treatment is available to be purchased. These studies monitor how well the test or treatment works in a wider population. Phase IV studies also allow the collection of information about side effects over a longer time. Phase IV studies are often used to see if the new test or treatment will work for other diseases or in different groups of people (for example, children).
What are the different types of clinical trials?
There are 3 main types of clinical trials.
- Treatment trials test new medicines, combinations of medicines, new medical devices or new approaches to surgery.
- Diagnostic or screening trials evaluate tests used to detect diseases.
- Prevention trials test new ways to prevent diseases. They might include medicines, vaccines, vitamins, or lifestyle or behaviour changes.
Do all participants in clinical trials get the new medicine?
In Phase III and IV clinical trials, people are often divided into groups. Depending on your group and the design of the clinical trial, you might receive:
- the new test or treatment
- the standard treatment
If there is no standard treatment you may receive a placebo. A placebo looks like a medicine but has no clinical effect.
You don’t get to decide which group you go in as people are randomly allocated to the different groups.
Why should I take part in a clinical trial?
You might be asked to take part in a clinical trial. If so, the benefits may include:
- earlier access to a new test or treatment
- closer monitoring than patients receiving standard care
- playing an active part in your treatment
- knowing that you are helping others by taking part
Are there any risks in taking part in a clinical trial?
There can also be risks from taking part in a clinical trial. These may include the following:
- Possible unpleasant side effects of the test or treatment.
- The inconvenience of being involved. You may need extra treatment, tests or hospital visits than usual.
- The test or treatment might not work for you.
You should talk with your doctors and the researchers before deciding to take part in a clinical trial.
A list of questions that you may want to ask can be found here.
Who can take part in a clinical trial?
Every clinical trial has a protocol. The protocol describes which people can take part in the clinical trial. This information is called the inclusion criteria and often includes age, sex, type of disease and previous treatments.
There will also be a list of characteristics that aren't wanted in each clinical trial. These are called the exclusion criteria.
What is informed consent?
Before you take part in a clinical trial, the researchers need to make sure that you understand what's involved. They will make sure you understand:
- the study's purpose
- how long the study will go for
- what tests and procedures you will have
- who you can contact if you have any concerns during the study
- any potential risks or benefits to you and your family and/or carers
This information is usually given to you in a document called the Patient Information Statement.
What happens if I change my mind and no longer want to take part?
If you decide that you no longer want to take part in a clinical trial, you should talk with the research team.
You will still be able to access standard care if you choose to leave the clinical trial.
After you leave the trial, your doctor will talk with you about other treatments for your disease.
The researchers can tell you what will happen to the data that they have already collected.
How do I find a list of clinical trials?
You can find out more about relevant clinical trials by:
- talking to your doctors
- contacting the relevant support groups or consumer health organisations in Australia
- looking at information on australianclinicaltrials.gov.au
If you are specifically looking for information about cancer trials, visit Cancer Australia's Australian cancer trials website.
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Last reviewed: June 2022