frequently asked questions

Clinical research is medical research that involves people. Individuals volunteer to participate in carefully conducted investigations that ultimately uncover better ways to treat, prevent, diagnose and understand human disease. Clinical research 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.

What are the different types of clinical research trials?

  • Treatment clinical trials test new ways to treat disease, such as a new therapy, a new drug or drug combination, or new approaches to surgery.
  • Prevention clinical trials seek better ways to keep people from getting a disease—or to prevent a disease from returning.
  • Diagnostic and screening clinical trials seek better ways to prove whether a person has a particular disease or condition.
  • Quality of life trials (or supportive care trials) explore and measure ways to improve comfort and the quality of life for individuals with a chronic illness.

What are the "phases" of clinical research trials? Clinical trials are conducted in phases, with each phase a different stage of testing. The trials at each phase have a different purpose and help scientists answer different questions.

In Phase I trials—Researchers test an experimental drug or treatment in a small group of people (20–80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.

In Phase II trials—The experimental study drug or treatment is given to a larger group of people (100–300) to see if it is effective and to further evaluate its safety.

In Phase III trials—The experimental study drug or treatment is given to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with commonly used treatments, and collect information that will allow the experimental drug or treatment to be used safely.

In Phase IV trials
—After a drug is licensed (approved by the FDA) or treatment is launched, researchers track its safety, seeking more information about a drug or treatment’s risks, benefits, and optimal use. These long–term studies involving large groups of participants continue to see if any unexpected side effects occur in a small percentage of individuals.

Are there risks in participating? Clinical trials may involve risks or discomfort. In considering a study’s risks, two factors are important: 1) the chance of any harm occurring and 2) the degree of harm that could result from participating in the study. Most clinical studies pose risks of minor discomfort, lasting only a short time, but some participants experience complications that require medical attention. The specific risks associated with any research protocol are described in detail in the consent document, which participants are asked to read and sign before taking part in a study. In addition, a member of the research team explains aloud the major risks of participating in the study and answers any questions participants have. Before deciding to participate, volunteers should carefully weigh these risks.

What are "blinded" (or "masked") studies? In single- or double-blind, also called single- or double-masked studies, participants do not know which medicine is being used, so they can describe what happens without bias. These studies are designed to prevent members of the research team and study participants from influencing the results. This allows scientifically accurate conclusions. In single-blind ("single-masked") studies, only the patient is not told what is being given. In a double-blind study, only the pharmacist knows; the other members of the research team are not informed. If medically necessary, however, it always is possible to find out what the patient is taking.

How is my confidentiality protected? A study participant’s identity is confidential. Although the information from a study may be widely used in other medical research, the identities of the individuals who participate are not shared. Participants who have talked about their experiences in clinical research have given permission for those experiences to be shared publicly.

Can I join any study I want? No. Each trial has specific guidelines about who can and who cannot participate, to ensure that the study includes people with the exact disease or condition being studied. These inclusion/exclusion criteria protect the safety of participants and ensure that the study results are dependable. Participation may sometimes be ruled out because of an individual’s age, stage of disease, other health issues, or previous treatments

How do I know what I am agreeing to do when I join a clinical trial? Members of the research team will explain all aspects of the study in advance, in a process known as "informed consent." Through informed consent, potential participants are given information about the study’s purpose, procedures, and potential risks and benefits—both initially and throughout the study. If you are considering joining a study, talk with your personal healthcare providers, family members, and friends. Do not rush the decision. And remember: It is important to ask questions.

Once in, can I leave a study? Participation is voluntary. Participants may withdraw at any time.

What is an IRB? An Institutional Review Board (IRB) is an independent committee of physicians, statisticians, community advocates, and others, which ensures that a clinical trial is ethical and that study participants' rights are protected. Each clinical trial conducted in the United States must be approved and monitored by an IRB, to ensure that the risks are as low as possible and are worth any potential benefits. In the United States, institutions that conduct or support biomedical research involving people must, by federal regulation, have an IRB that initially approves, and periodically reviews, the research.

Who sponsors clinical trials? Clinical trials are sponsored or funded by various kinds of organizations or individuals, including physicians, medical institutions, foundations, voluntary groups, and pharmaceutical companies, in addition to such federal agencies as the National Institutes of Health, the Department of Defense, and the Department of Veterans Affairs. Trials can occur in such varied locations as hospitals, universities, doctors’ offices, or community clinics.