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JAMA Patient Page
March 24 2010

Randomized Controlled Trials

JAMA. 2010;303(12):1216. doi:10.1001/jama.303.12.1216

Medical research answers many questions about health, illness, and treatment options. Evaluating new medicines and other treatments may involve research using randomized controlled trials. In such trials the participants who receive the treatment under study are assigned at random (by chance, like the flip of a coin). This is necessary to ensure that the outcomes are determined only by the treatment under study and not by other factors that could otherwise influence treatment assignment. Other participants who, by the randomization process, serve as controls receive a standard treatment or placebo treatment (a pill or procedure that does not include active ingredients). The March 24/31, 2010, issue of JAMA includes a review article about clinical trials. This Patient Page is based on one previously published in the June 21, 2006, issue of JAMA.

Clinical trials

Clinical trials are designed to answer a specific question about a treatment, usually the safety and efficacy (how well it works under optimal conditions) of the treatment. Volunteers who meet specific criteria, including having the condition being studied, receive an explanation and, if they choose, join the trial. This informed consent process should include explaining the random treatment assignment as well as the risks and possible benefits of the trial and often includes a written form to document those issues and the volunteer's consent. In a double-blind trial, neither the clinicians caring for the patients nor the participating volunteers know who has been assigned to the active treatment until the trial is concluded (unless a medical problem requires that the information be released before that). In a single-blind trial, the investigators know the treatment assignments but the participants do not. Blinding procedures protect against the influence of bias (prejudice) for or against the treatment being studied.

Research ethics

Before any persons can be enrolled in a clinical trial, the study must receive approval by an ethics committee (called an institutional review board in the United States). This is a panel of individuals, including doctors and community members, who discuss all of the proposed research studies at a specific institution (university, medical center, or hospital). The ethics committee reviews the purpose of the study and its design, the risks and possible benefits to the participants, and the adequacy of the informed consent process.

Participating in a clinical trial

  • Sometimes participating in clinical trials may allow patients to receive experimental treatments, especially when they have a disease that has not responded to other therapies.

  • All participants in clinical trials are volunteers who can withdraw from a trial if they choose.

  • Participants should have the option to review the purpose and design of the study and understand whether control participants will receive standard therapy or placebo.

  • Participants should have all their questions answered before agreeing to participate in a clinical trial.

  • If you are thinking of joining a clinical trial, discuss participation with your doctor to be sure it fits with your ongoing care.

For more information

Inform yourself

To find this and previous JAMA Patient Pages, go to the Patient Page link on JAMA's Web site at http://www.jama.com. A Patient Page on cancer clinical trials was published in the June 4, 2004, issue; and one on supporting medical research was published in the September 21, 2005, issue.

Sources: National Cancer Institute, National Institutes of Health, Centers for Disease Control and Prevention

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call 312/464-0776.