Clinical trials

Doctors and researchers use clinical trials to find new ways of preventing, diagnosing or treating conditions and diseases. Without clinical trials, our ability to improve people’s health would be held back. Most of the current treatments and devices we take for granted would not be available if clinical trials had not tested them first. Taking part can give some people access to new treatments, but there are both benefits and risks for participants.

How clinical trials are regulated#

Clinical trials are tightly regulated to make the process as safe as possible for participants. Research involving humans must be assessed and approved by a human research ethics committee before it can go ahead. Trials are also overseen by the relevant regulatory authority, which publishes guidance on how they should be conducted.

Clinical trials differ depending on what they are designed to achieve. The three major types focus on:

• prevention, looking at ways of preventing disease, including potential treatments such as medications, vaccines or vitamins, or lifestyle changes
• screening or diagnosis, studying new tests to see how well they detect diseases or conditions
• treatment, testing new drugs, devices or surgical techniques

Phases of clinical trials#

Trials of drugs and treatments pass through several phases as they progress from a laboratory experiment to a new treatment. Knowing about these phases helps you understand who can take part in each stage, and the risks and benefits involved:

• Pre-clinical studies: the safety and effectiveness of drugs and treatments is tested in animals.
• Phase I: the safety and side effects of a drug are tested in a small number of healthy volunteers or participants.
• Phase II: the safety and effectiveness of a drug are tested in 100 to 300 volunteers who usually have the condition the drug is designed to treat.
• Phase III: the effectiveness of the treatment is tested, and compared with standard treatments or an inactive placebo, in a larger group of people who have the condition.
• Phase IV: the drug or treatment is tested for long-term effects after it has been released for doctors to use.

Informed consent#

People deciding whether to enter a clinical trial must understand all the essential facts, benefits and risks. This information should be set out clearly in a patient information statement approved by an ethics committee. Understanding and agreeing to this information is called informed consent.

You will need to know the details of the trial, including:

• the purpose of the trial and how long it will take
• the procedures involved
• the risks and benefits, and the effects on you, your family or carers
• the costs involved
• your key contact people during the trial

Ask questions if anything is unclear. Writing down a list of questions for your doctor is a good way to make sure all your concerns are covered, and it can help to research clinical trials beforehand. There are also special considerations for specific groups, such as pregnant women and the unborn fetus, and children.

Clinical trials are voluntary, and you should not feel pressured into taking part. If you are already seeing a doctor for a condition, your care will not be affected if you choose not to enter a trial. If you are in a trial, you can choose to leave at any time, and your standard treatment will not be affected.

Inclusion and exclusion criteria#

Before a trial begins, researchers must choose particular types of participants so that meaningful results are obtained. The characteristics of people who can enter a trial are known as inclusion criteria, and the characteristics that prevent entry are known as exclusion criteria.

Risks and benefits#

A key benefit is knowing that you are contributing to potential future treatments for people around the world, and you may gain access to new treatments. It is important to understand the risks before agreeing to participate, so speak with your doctor about all of them. Potential risks include:

• The experimental treatment might have side effects that are different from, or more serious or unpleasant than, those of the current standard treatment.
• The trial might involve inconvenience, such as keeping a diary or collecting urine samples for 24 hours, or additional tests, hospital visits or complicated medications.
• The experimental treatment might not help your condition, or you might be placed in the group that receives the standard treatment or a placebo.

Key points#

• Taking part in a trial can give some people access to new treatments.
• There are both benefits and risks for participants in clinical trials.
• Drugs and treatments must pass through phases of testing.
• These phases start with pre-clinical studies, where the safety and effectiveness of drugs and treatments is tested in animals.
• In Phase IV, a drug or treatment is tested for long-term effects after it has been released for doctors to use.