Northwestern University Feinberg School of Medicine
Research

Frequently Asked Questions About Clinical Trials

 What is a clinical trial?

Clinical trials are at the heart of all medical advances. They’re conducted with the help of human volunteers and aim to find out if a new drug, surgical procedure, medical device or new way of using an existing treatment is safe and effective.

Clinical trials follow strict ethical and legal codes and regulations to protect the safety and rights of volunteers. These rules are set and enforced by individuals and groups at the sites where the clinical trials take place. Such groups include an Institutional Review Board and government agencies such as the Food and Drug Administration and the Office of Human Research Protections.

 What is clinical science?

Clinical science is medical science that involves people. People volunteer to participate in carefully conducted investigations that ultimately uncover better ways to treat, prevent, diagnose and understand human disease. Clinical science includes trials that test new treatments and therapies, as well as long–term natural history studies, which provide valuable information about how disease and health progress.

 Why volunteer?

Without volunteers, we wouldn’t have many of the medicines and scientific discoveries we enjoy the benefits of today. Clinical trials offer you an opportunity to help scientists find better ways of preventing and treating diseases, improving health for all. By volunteering in a clinical trial, you or someone you love could:

  • Have access to a new medical treatment before anyone else
  • Help doctors and scientists better understand a disease, how it affects our health and how best to treat it
  • Help move science and medicine forward to improve the health of others in your community

 Who participates in clinical trials?

All clinical trials have guidelines about who can participate, called inclusion and exclusion criteria. Both sets of criteria are based on factors such as age, gender, the type and stage of a disease, previous treatment history and other medical conditions.

Before joining a clinical trial, a participant must qualify for the study. Some studies look for participants with illnesses or conditions to be studied in the clinical trial, while others need healthy volunteers. Some studies need both types of volunteers.

Inclusion and exclusion criteria are not used to reject people personally; rather, the criteria are used to see if the study is a good fit for participants, keep them safe and help ensure scientists can find the information they need.

 Who is a healthy volunteer in a clinical trial?

In some studies, volunteers who are in good health are needed to test a new drug or device that has never been given to people or to only a few people. In clinical trials, these are often called “healthy volunteers.” Though it can be hard to know what “healthy” means, a healthy volunteer is typically a person who is free from the disease or condition being studied or who has no major health problems.

While participating in a clinical trial, a healthy volunteer is given a drug not to test if it will treat a disease, but rather to build new knowledge about the drug and to see if people can safely use it. Results from healthy volunteers are compared to results from patient volunteers who do have the disease or condition.

 What is a patient volunteer?

A patient volunteer has a known health problem and participates in a study to better understand, diagnose, treat or cure that disease or condition. Like healthy volunteers, patient volunteers may participate in studies testing drugs, devices or interventions designed to prevent or treat disease.

In some studies, patient volunteers may be put into a group to take an inactive drug called a placebo. Placement in placebo groups is random, so each volunteer has an equal chance of getting either the active drug or the placebo.

For most studies, neither you nor your doctor will know if you are getting the drug or the placebo. This is to prevent any bias in the study results.

 What questions should I ask?

Here are some questions to ask your doctor to help you decide if you want to take part in a clinical trial:

The study

  • What is the purpose of the study?
  • Who will fund the study? 
  • How are the results and the safety of participants monitored?
  • How long will the study last? 
  • What will I be asked to do if I participate? 

Possible risks and benefits

  • What are my possible short-term benefits?
  • What are my possible long-term benefits?
  • What are my short-term risks, such as side effects?
  • What are my possible long-term risks? 
  • What other options do people with my disease have?
  • How do the possible risks and benefits of this trial compare with those options?

Participation and care

  • What kinds of therapies, procedures and/or tests will I have during the trial?
  • Will they hurt and, if so, for how long?
  • How often does the study require me to go to the doctor or clinic?
  • Will I be hospitalized? If so, how often and for how long?
  • How do the tests in the study compare to those I would have outside of the trial?
  • Will I be able to take my regular medications while in the clinical trial?
  • Where will I have my medical care?
  • Who will be in charge of my care?
  • What follow-up will there be?
  • What will happen at the end of the study?
  • Will I be able to see my own doctor?

Personal issues

  • How could being in this study affect my daily life? 
  • Can I talk to other people in the study?

Cost issues

  • Will I have to pay for any part of the trial?
  • If so, what will the charges likely be?
  • What is my health insurance likely to cover?
  • Who can help answer any questions from my insurance company or health plan?
  • Is there any reimbursement for travel costs or child care?

Tips for asking your doctor about trials

  • Take a family member or friend along for support and to help ask questions or record answers.
  • Plan your questions in advance so you don’t leave any out. Don't hesitate to ask any new questions you think of while you're there.
  • Write down the answers so that you can review them whenever you want.
  • Ask about bringing a tape recorder to make a taped record of what's said (even if you write down answers).

 What are the risks?

Some treatments that are being tested may have side effects that can be unpleasant, serious or even life-threatening. Because the treatments being studied are new, doctors don’t always know what the side effects will be. Many side effects last a short time and go away when the treatment is stopped. Others can be long-lasting or permanent. Some side effects appear during treatment, while others may not show up until after the treatment is over. The risks depend on the treatment being studied, and all known risks should be fully explained to you by the scientists in advance.

 How am I protected?

Informed Consent

To help you decide if you want to be in a study, the study team is required to go through key facts about a clinical trial with you. This process is called informed consent.

With the help of a document called the informed consent form, the study team will explain the details of the study to you and answer any questions you might have about the study and your participation in it. During informed consent, the study team should disclose:

  • That the study involves an untested drug or device
  • The purpose of the investigation
  • How long the study will take
  • What you will be asked to do if you participate
  • What parts of the study are experimental
  • Possible risks or discomforts
  • Other procedures or treatments you might want to think about instead of those being studied
  • Who will have access to study records (for example, the FDA) and how the records will be kept confidential
  • Whether any medical treatments are available if you are hurt, what those treatments are, where they can be found and who will pay for the treatment
  • Who to contact with questions about the study, your rights or if you get hurt
  • That you can stop the study at any time without penalty

This process also continues throughout a study, so this information is constantly available to participants.

If you don’t understand the informed consent process or forms, be sure to ask the doctor or another medical person to explain it. Make sure you understand all of it before you agree to be in the study. It’s okay to ask questions.

Before you can take part in the study, you must sign the informed consent form to indicate you have been given this information and understand it. The informed consent form is not a contract. You can leave the study at any time, for any reason.

Institutional Review Board

Each clinical trial in the United States must be approved and monitored by an Institutional Review Board (IRB) to ensure that the risks are minimal and are worth any potential benefits. An IRB is an independent committee that consists of physicians, statisticians and members of the community who ensure that clinical trials are ethical and that the rights of participants are protected. Federal regulations require all institutions in the United States that conduct or support biomedical science involving people to have an IRB initially approve and periodically review the study.

For further reading about protocols, see: 

For more information on participants’ privacy and confidentiality, see:

FDA’s Drug Review Process:

 What are data-monitoring committees?

These committees are used mainly when one treatment is being compared to another. These committees are particularly important in tests of treatments for serious or life-threatening disease. These experts review information from studies to make sure they are being done in a way that is safest for the volunteers. During a study, if the committee finds that the treatment is harmful or of no benefit, it will stop the study. If a study shows that one treatment works better than another, the committee stops the study and all volunteers are offered the better treatment.

 What happens after a clinical trial is completed?

Next steps vary from study to study. You might be allowed to continue taking the study medication if you had a good response to it during the study, or you might be given a chance to take the study medication if you didn’t receive it. Most often, participation ends when the study ends because full safety information is not yet known.

Participants may also be given results from the study. Ask the study team members if the results have been or will be published. You can also find published study results by searching for the official name or protocol ID number in the National Library of Medicine's PubMed database.

After a clinical trial is over, scientists carefully look at the information collected during the study to determine the drug's effectiveness, if it is safe and if there are any side effects. Depending on the results, scientists then decide whether to stop or continue testing the new drug or treatment. If scientists find the results are medically important, they may submit them to journals or scientific meetings for review by others in their field.

Results are also shared with government agencies in charge of the approval for new drugs, devices and treatments, such as the FDA. If a drug is approved, pharmaceutical companies may continue to conduct studies that compare the new drug’s safety, effectiveness and cost to other drugs already on the market or assess its long-term effectiveness and impact on quality of life.

Once a new approach has been shown to be safe and effective in a clinical trial, it may become the standard of medical practice.