Confused by some of the terminology involved with clinical research?
Try our Glossary of Terms.
Adverse Event – Any change in health that occurs in a person after he or she enrolls in a clinical trial. Not every adverse event is related to the treatment or test being studied, but researchers must report all adverse events to the Food and Drug Administration (FDA).
Approved Drugs – In the United States, the FDA approves prescription drugs. Before a drug can be prescribed, it must undergo an extensive FDA approval process. This process involves first testing the drug on animals or in medical labs. If found to be safe by the FDA and approved for the next phase of study, the drug is then tested for safety and effectiveness in humans (clinical trials). The drug manufacturer then files a New Drug Application to the FDA, which reviews the application and either approves or rejects it.
Arm – A treatment or test group in a clinical trial. Trials that offer more than one treatment are said to have multiple arms.
Baseline – A person's health status before he or she begins a clinical trial. Baseline measurements are used as a reference point to determine a participant's response to the experimental treatment.
Blind Trial – A blind trial is one in which the participant is not told which arm — experimental or control — of the clinical trial he or she is on. See also control group, double-blind trial.
Clinical Trial – A carefully designed investigation of the effects of drug, medical treatment or device on a group of patients. Also called research studies or medical research, clinical trials help establish the safety and effectiveness of new drugs or treatments.
Coordinator – See Study Coordinator.
Compassionate Use – Providing people experimental treatments and drugs that haven't been approved by the FDA. This is typically only done for very sick individuals who have no other treatment options, and it often requires approval from the FDA on a case-by-case basis.
Control Group – A group of clinical trial participants that receives the placebo or standard therapy for a condition while another group is given the experimental treatment. The control group serves as a measuring stick to gauge the effectiveness of the experimental treatment.
Diagnostic Trial – A trial that's conducted to find better tests or procedures for diagnosing a particular disease or condition. Diagnostic-trial participants usually already exhibit signs or symptoms of the particular disease or condition being studied.
Dose-Limiting Toxicity – The appearance of side effects during treatment that are severe enough to prevent further increase in dosage or strength of treatment, or to prevent continuation of treatment at any dosage level.
Double-Blind Trial – A clinical trial in which neither the participants receiving the treatments nor the researchers administering the treatments are aware of which group is receiving the experimental treatment. The purpose is to eliminate any bias in reporting of results.
Efficacy – The ability of a drug, test or treatment to relieve symptoms, detect or eliminate the disease. A treatment is said to have efficacy if certain positive outcomes — for example, shrinking of a tumor — chosen before the start of the trial occur.
Epidemiology – The branch of science that studies the incidence, distribution, and control of a disease among a specific group.
Exclusion Criteria – The standards used to determine whether a person may or may not be allowed to participate in a clinical trial. The most important criteria used to determine appropriateness for clinical trial participation include age, sex, the type and stage of a disease, previous treatment history, and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally, but rather to identify appropriate participants and keep them safe.
Food and Drug Administration (FDA) – A government agency that enforces laws on the manufacture, testing and use of drugs and medical devices. All drugs and medical devices must be approved by the FDA before they can be used by the general public.
Generalizability of Results – The extent to which clinical trial results apply to individuals being treated outside the trial. The results and conclusions of a study of one group of people may not apply equally to another group. Researchers must take care not to generalize their results too broadly. Often they do more studies to see how the treatment works in different groups of people.
Inclusion Criteria – The standards used to determine whether a person may be allowed to participate in a clinical trial. The most important criteria used to determine appropriateness for clinical trial participation include age, sex, the type and stage of a disease, treatment history, and other medical conditions. See also exclusion criteria.
Informed Consent – A discussion of all procedures, benefits, risks and expectations of a clinical trial between the clinical investigators and the potential patients. The FDA requires that all patients sign an informed consent before participating in a trial. A volunteer patient must be fully informed of the potential risks and benefits of the experimental treatment as well as other treatment options. There must be no penalties for declining to participate and participants may withdraw from the trial at any time.
Institutional Review Board (IRB) – A board consisting of health care professionals and representatives of the lay public. The board scrutinizes all trial activities including recruitment, advertising and potential risks. The IRB also makes sure that FDA regulations are being followed in a particular trial.
Investigational New Drug (IND) – An experimental drug tested in a clinical trial.
Investigator – The person in charge of a research study. If there is more than one investigator, one person may be named as the principal investigator.
Landmark Study – A study in clinical research that marks the discovery of a new method to diagnose or treat a disease or condition.
Maximum-Tolerated Dose – The highest dosage of a drug, drug combination or other treatment modality that a person can safely tolerate.
Medical Researcher – See investigator.
Monitoring – Oversight and administrative efforts that monitor a participant's health during a clinical trial. The government and other trial funding agencies require data and safety monitoring boards to oversee clinical trials. They want to be certain that safety measures are in place to protect participants.
Multicenter Research Trial – A clinical trial that's conducted at more than one medical center or clinic. Most large clinical trials are conducted at several research centers. The benefits of multicenter trials include a larger number of participants, different geographic locations, various ethnic groups and the ability to compare results among centers, all of which increase the generalizability of the study.
Orphan Drugs – Medications used to treat rare diseases and conditions.
Peer Review - A review of trial reports by scientists who aren’t involved with the trial. The findings of a trial usually are reviewed before being accepted for publication. When the work is either published or presented at a conference, the researchers open both their study protocol and results up to critical review by the scientific community at large to verify the merit of each study. See also protocol.
Pivotal Trial – A study which definitively answers the question of safety and efficacy of the investigational product being studied and upon which the regulatory approval of the product hinges.
Placebo (control) Group – A group that receives an inactive treatment for comparison with the active treatment(s) being tested. Often in a trial, to compare two different treatments, participants will be given both a placebo with the appearance of a therapy and an actual dose of another therapy. Placebos are generally used only in situations in which the disease is not life-threatening. It's unethical to give placebos in some circumstances, such as when a medical condition requires some form of treatment that's already approved. See also control group.
Preclinical Studies – A laboratory or animal study that's done to determine if a new treatment is safe and effective enough to be studied in humans.
Protocol – The specific set(s) of goals and procedures that define what will happen in a trial. Protocols are developed before a trial so that participants know what will happen and other researchers can replicate the studies.
Prospective – A study where subjects/patients are selected for the study and enrolled before the treatment being studied is applied. This is opposed to a retrospective study, one in which the treatment has already been applied to the patient and, after the fact, data are collected about its effectiveness or safety. Prospective studies usually are more highly respected and have more validity and reliability.
Primary Prevention – The identification of high-risk population and instituting treatment as a preventative measure.
Randomization – A process that reduces the likelihood of bias by assigning people to treatment groups by chance alone (randomly). When groups are created by random assignment, individual characteristics are less likely to make the results inaccurate.
Research Study – See clinical trial.
Retrospective Study - one in which the treatment has already been applied to the patient and, after the fact, data are collected about its effectiveness or safety.
Sample – The group of people who participate in a trial. Generally, the greater the number of participants, the lesser the likelihood of reaching a false conclusion. However, when a drug shows effectiveness against a life-threatening condition, researchers may need only a small sample of people to determine if the treatment is effective. Still, they must test another group to learn about the risks associated with the treatment.
Secondary Prevention – A trial that identifies a group that already has a problem and provides treatment to prevent further incidents.
Side Effects – Any negative effects of a drug or treatment. Experimental drugs and treatments must be evaluated for both immediate and long-term side effects such as headache, nausea, hair loss, skin irritation or other physical problems. See also adverse event.
Sponsor – The organization that develops the treatment, drug or test, designs the study, and pays for the trial.
Standard Treatment – An FDA-approved treatment currently in wide use. Generally, the goal of the clinical trial is to introduce an investigation treatment that is safer and more effective than the standard treatment.
Study Coordinator – The person at a medical center or research facility who manages the daily activities of the study, including coordinating the treatment or testing of participants.
Toxicity – Literally, the state of being poisonous. In studies, toxicity refers to specific adverse events attributable to a drug or treatment.
Treatment Group – The group of participants that receives an experimental treatment. See also control group.