The Basics About Clinical Trials

What is a clinical trial?

What are the different phases of a clinical trial?

What is Informed Consent?

What are the inclusion and exclusion criteria?

What are the risks and benefits of participating in a clinical trial?

What is a clinical trial?

Clinical trials are research studies performed in people with an aim to find new ways to diagnose, treat and prevent diseases and medical conditions. Through clinical trials, doctors determine if a new treatment is more effective and/or has less harmful side effects than the standard treatment. In fact, most drugs and medical devices being used today are the results of past clinical trials. When you volunteer to participate in a clinical trial, you help shape the future of medicine. However, taking part in a clinical trial is purely a personal decision and it should carefully considered.


What are the different phases of a clinical trial?

 New treatments usually have to go through a series of steps called “phases” to test whether they are safe and effective. Each phase is designed to answer certain questions.

Phase I:  Is the treatment safe?

Phase I studies are conducted to look at the side effects of the new treatment. Phase I trials involve only a small number of people (20-80), who are often healthy volunteers.

Phase II: Does the treatment work?

When a new drug is found to be reasonably safe in a phase I trial, it is tested in phase II clinical trial to find out if it works. The new treatment is usually tested in a large group of people (100–300) who have the disease/condition to determine its effectiveness and to further study its safety.

Phase III: Is it better than what is already available?

In Phase III clinical trials, new treatments that show the potential to work in phase II are compared against the current standard treatment for safety and effectiveness. Phase III trials involve larger numbers of patients (hundreds or sometimes thousands) who have the disease or condition. Patients are often picked at random (called randomized) to receive the new treatment or the standard treatment (or sometimes a placebo). Phase III studies confirm effectiveness, monitor side effects, and compare it with the standard of care.

Phase IV: What else do we need to know?

Phase IV trials are done after a drug has been approved by the FDA. Researchers track the safety of the new drug in various populations and any side effects associated with long-term use.

What is Informed Consent?

Informed consent is the process through which you will learn key details about the trial before you decide whether to participate. Members of the research team will explain details of the study such as purpose, procedures and risks and benefits involved. They will also discuss your rights, including your right to make the decision about taking part and leaving the study at any time. If you agree to take part in the study, you sign the informed consent form.

For children, a parent or guardian has to give consent for them to take part in a trial.

Participants can change their mind after signing the informed consent form and can withdraw from a trial at any stage.

What are the inclusion and exclusion criteria?

All clinical trials have guidelines about who can or cannot take part, called inclusion/exclusion criteria. These criteria help to make sure that the people who might benefit most from a new treatment are included in the trials while excluding those for whom the new treatment might not be safe or appropriate. Most often, inclusion and exclusion criteria are related to age, gender, type and stage of a disease, previous or current medications, other existing medical conditions and recent participation in a clinical trial.

To find out more about the inclusion and exclusion criteria for the trials at UofL that are open to recruitment, please visit the current trials page.

What are the risks and benefits of participating in a clinical trial?

There are great benefits to participating in a clinical trial:

You get additional education about your disease or condition

You may get effective treatment not yet available to the public.

Regular and careful attention from some of the best doctors

Contributing to research that may save lives in the future

Risks vary by study, but generally involve:

Not being able to choose which treatment, you get.

Treatment side effects

The new treatment may not work for you.

Inconveniences such as for travel and time to attend clinic appointments.

 To learn more about the basics of clinical trials click here