Glossary of Terms Used in Clinical Trials

A

Adverse reaction or event -- An unwanted, negative effect of a certain intervention or test. Researchers monitor for adverse reactions to determine a new drug's safety during a clinical trial.

Approved or approval -- Before doctors can use new medications or devices, the Food and Drug Administration (FDA) must approve them. The FDA bases its decisions on the safety and effectiveness of the new product from preclinical studies on animals or laboratory tests and on clinical trials on humans. Some clinical trials test approved drugs for new uses, while others test unapproved drugs.

Arm -- One of the intervention groups in a clinical trial. A clinical trial comparing two doses of a new medication with a placebo would have three arms (dose 1, dose 2, and placebo).

B

Baseline -- The time point when a clinical trial starts, before any treatment is begun. Researchers often compare baseline tests to those made at the end of the study to see how well the treatments worked.

Bias -- A slanted perspective that prevents researchers from getting true answers to research questions. Clinical trials use several methods to eliminate bias, including randomization, blinding, and the use of strict protocols.

Blind or blinding -- When the researchers, the participants, or both, do not know which people are getting which potential treatment being studied in a clinical trial. The process of blinding improves the accuracy of a study's results because no one is unconsciously influenced by the knowledge. If only researchers or only participants are blinded, the study is often called single blind. If both researchers and participants are blinded, the study is double blind. Because the terms "single blind" and "double blind" are imprecise, many researchers prefer to specify who is blinded -- investigators, participants, outcome assessors, or statisticians. (See http://www.acpjc.org/shared/glossary.htm)

C

Capacity -- In clinical trials, capacity means a person's ability -- or competence -- to understand and make informed decisions about participating in the experiment.

Clinical -- Related to observation of and intervention on human participants.

Clinical research coordinator (CRC) -- The coordinating administrator of a clinical trial at a certain site. CRCs can be certified after two years of work by studying a program and passing an examination.

Clinical trial -- An experimental research study that tests new medical interventions on people. These interventions may include drugs, devices, or other instruments.

Compassionate use -- A method of accessing experimental interventions before FDA approval, usually for sick patients without other treatment options. See expanded access.

Complementary medicine -- A group of approaches to healing not normally used in conventional (or allopathic) medicine, such as chiropractic, acupuncture, and herbs. Other terms include alternative and integrative medicine.

Confidentiality -- Maintaining the privacy of personal information. Clinical trials should ensure that participants are not identifiable in their published work and that only designated researchers access private information.

Consent -- See informed consent.

Contract Research Organization (CRO) -- A company contracted by the sponsoring entity to manage specific parts of a clinical trial.

Control or control group -- A comparison group for an experimental agent in a clinical trial. A control group receives standard treatment (if it exists) or a placebo.

Controlled clinical trial -- A clinical trial in which one or more groups receive an experimental intervention and another group acts as the control (or comparison) group.

Crossover trial -- A study design with two or more groups, where participants in one group receive one intervention for a period of time, then switch over to the second intervention (and vice versa -- participants in the other group start with the second intervention and switch back to the first).