Glossary of Clinical Trials Terms
The following glossary was prepared to help the consumer become familiar with
the most common terms used in clinical trials. ADVERSE
REACTION: (Adverse Event.) An unwanted effect caused by the
administration of drugs. Onset may be sudden or develop over time (See Side
Effects).
ADVOCACY AND SUPPORT GROUPS: Organizations and
groups that actively support participants and their families with valuable
resources, including self-empowerment and survival tools.
APPROVED DRUGS: In the U.S., the Food and
Drug Administration (FDA) must approve a substance as a drug before it can be
marketed. The approval process involves several steps including pre-clinical
laboratory and animal studies, clinical trials for safety and efficacy, filing
of a New Drug Application by the manufacturer of the drug, FDA review of the
application, and FDA approval/rejection of application (See Food and Drug
Administration).
ARM: Any of the treatment groups in a randomized
trial. Most randomized trials have two "arms," but some have three "arms," or
even more (See Randomized
Trial).
BASELINE: 1. Information gathered at the
beginning of a study from which variations found in the study are measured. 2. A
known value or quantity with which an unknown is compared when measured or
assessed. 3. The initial time point in a clinical trial, just before a
participant starts to receive the experimental treatment which is being tested.
At this reference point, measurable values such as CD4 count are recorded.
Safety and efficacy of a drug are often determined by monitoring changes from
the baseline values.
BIAS: When a point of view prevents impartial
judgment on issues relating to the subject of that point of view. In clinical
studies, bias is controlled by blinding and randomization (See Blind
and Randomization).
BLIND: A randomized trial is "Blind" if the
participant is not told which arm of the trial he is on. A clinical trial is
"Blind" if participants are unaware on whether they are in the experimental or
control arm of the study; also called masked. (See Single Blind
Study and Double Blind
Study).
CLINICAL: Pertaining to or founded on
observation and treatment of participants, as distinguished from theoretical or
basic science.
CLINICAL ENDPOINT: See Endpoint.
CLINICAL INVESTIGATOR: A medical researcher
in charge of carrying out a clinical trial's protocol.
CLINICAL TRIAL: A clinical trial is a research
study to answer specific questions about vaccines or new therapies or new ways
of using known treatments. Clinical trials (also called medical research and
research studies) are used to determine whether new drugs or treatments are both
safe and effective. Carefully conducted clinical trials are the fastest and
safest way to find treatments that work in people. Trials are in four phases:
Phase I tests a new drug or treatment in a small group; Phase II expands the
study to a larger group of people; Phase III expands the study to an even larger
group of people; and Phase IV takes place after the drug or treatment has been
licensed and marketed. (See Phase I, II, III,
and IV
Trials).
COHORT: In epidemiology, a group of individuals
with some characteristics in common.
COMMUNITY-BASED CLINICAL TRIAL (CBCT): A clinical
trial conducted primarily through primary-care physicians rather than academic
research facilities.
COMPASSIONATE USE: A method of providing
experimental therapeutics prior to final FDA approval for use in humans. This
procedure is used with very sick individuals who have no other treatment
options. Often, case-by-case approval must be obtained from the FDA for
"compassionate use" of a drug or therapy.
COMPLEMENTARY AND ALTERNATIVE THERAPY:
Broad range of healing philosophies, approaches, and therapies that Western
(conventional) medicine does not commonly use to promote well-being or treat
health conditions. Examples include acupuncture, herbs, etc. Internet Address:
http://www.nccam.nih.gov/.
CONFIDENTIALITY REGARDING TRIAL PARTICIPANTS:
Refers to maintaining the confidentiality of trial participants including
their personal identity and all personal medical information. The trial
participants' consent to the use of records for data verification purposes
should be obtained prior to the trial and assurance must be given that
confidentiality will be maintained.
CONTRAINDICATION: A specific
circumstance when the use of certain treatments could be harmful.
CONTROL: A control is the nature of the
intervention control.
CONTROL GROUP: The standard by which
experimental observations are evaluated. In many clinical trials, one group of
patients will be given an experimental drug or treatment, while the control
group is given either a standard treatment for the illness or a placebo (See
Placebo
and Standard
Treatment).
CONTROLLED TRIALS: Control is a standard
against which experimental observations may be evaluated. In clinical trials,
one group of participants is given an experimental drug, while another group
(i.e., the control group) is given either a standard treatment for the disease
or a placebo.
DATA SAFETY AND MONITORING BOARD (DSMB): An
independent committee, composed of community representatives and clinical
research experts, that reviews data while a clinical trial is in progress to
ensure that participants are not exposed to undue risk. A DSMB may recommend
that a trial be stopped if there are safety concerns or if the trial objectives
have been achieved.
DIAGNOSTIC TRIALS: Refers to trials that
are are conducted to find better tests or procedures for diagnosing a particular
disease or condition. Diagnostic trials usually include people who have signs or
symptoms of the disease or condition being studied.
DOSE-RANGING STUDY: A clinical trial in which two
or more doses of an agent (such as a drug) are tested against each other to
determine which dose works best and is least harmful.
DOUBLE-BLIND STUDY: A clinical trial design in
which neither the participating individuals nor the study staff knows which
participants are receiving the experimental drug and which are receiving a
placebo (or another therapy). Double-blind trials are thought to produce
objective results, since the expectations of the doctor and the participant
about the experimental drug do not affect the outcome; also called double-masked
study. See Blinded
Study, Single-Blind
Study, and Placebo.
DOUBLE-MASKED STUDY: See Double-Blind
Study.
DRUG-DRUG INTERACTION: A modification of
the effect of a drug when administered with another drug. The effect may be an
increase or a decrease in the action of either substance, or it may be an
adverse effect that is not normally associated with either drug.
DSMB: See Data Safety
and Monitoring Board.
EFFICACY: (Of a drug or treatment). The
maximum ability of a drug or treatment to produce a result regardless of dosage.
A drug passes efficacy trials if it is effective at the dose tested and against
the illness for which it is prescribed. In the procedure mandated by the FDA,
Phase II clinical trials gauge efficacy, and Phase III trials confirm it (See
Food and Drug
Administration (FDA), Phase II
and III
Trials).
ELIGIBILITY CRITERIA: Summary criteria for
participant selection; includes Inclusion and Exclusion criteria. (See Inclusion/Exclusion
Criteria)
EMPIRICAL: Based on experimental data, not
on a theory.
ENDPOINT: Overall outcome that the protocol
is designed to evaluate. Common endpoints are severe toxicity, disease
progression, or death.
EPIDEMIOLOGY: The branch of medical
science that deals with the study of incidence and distribution and control of a
disease in a population.
EXCLUSION/INCLUSION CRITERIA: See Inclusion/Exclusion
Criteria.
EXPANDED ACCESS: Refers to any of the FDA
procedures, such as compassionate use, parallel track, and treatment IND that
distribute experimental drugs to participants who are failing on currently
available treatments for their condition and also are unable to participate in
ongoing clinical trials.
EXPERIMENTAL DRUG: A drug that is not FDA
licensed for use in humans, or as a treatment for a particular condition (See
Off-Label
Use).
FDA: See Food and Drug
Administration.
FOOD AND DRUG ADMINISTRATION (FDA): The U.S.
Department of Health and Human Services agency responsible for ensuring the
safety and effectiveness of all drugs, biologics, vaccines, and medical devices,
including those used in the diagnosis, treatment, and prevention of HIV
infection, AIDS, and AIDS-related opportunistic infections. The FDA also works
with the blood banking industry to safeguard the nation's blood supply. Internet
address: http://www.fda.gov/.
HYPOTHESIS: A supposition or assumption
advanced as a basis for reasoning or argument, or as a guide to experimental
investigation.
INCLUSION/EXCLUSION CRITERIA: The medical or
social standards determining whether a person may or may not be allowed to enter
a clinical trial. These criteria are based on such factors as age, gender, 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.
IND: See
Investigational New Drug.
INFORMED CONSENT: The process of learning the
key facts about a clinical trial before deciding whether or not to participate.
It is also a continuing process throughout the study to provide information for
participants. To help someone decide whether or not to participate, the doctors
and nurses involved in the trial explain the details of the study.
INFORMED CONSENT DOCUMENT: A document that
describes the rights of the study participants, and includes details about the
study, such as its purpose, duration, required procedures, and key contacts.
Risks and potential benefits are explained in the informed consent document. The
participant then decides whether or not to sign the document. Informed consent
is not a contract, and the participant may withdraw from the trial at any time.
INSTITUTIONAL REVIEW BOARD (IRB): 1. A
committee of physicians, statisticians, researchers, community advocates, and
others that ensures that a clinical trial is ethical and that the rights of
study participants are protected. All clinical trials in the U.S. must be
approved by an IRB before they begin. 2. Every institution that conducts or
supports biomedical or behavioral research involving human participants must, by
federal regulation, have an IRB that initially approves and periodically reviews
the research in order to protect the rights of human participants.
INTENT TO TREAT: Analysis of clinical trial
results that includes all data from participants in the groups to which they
were randomized ( See Randomization)
even if they never received the treatment.
INTERVENTION NAME: The generic name of the
precise intervention being studied.
INTERVENTIONS: Primary interventions
being studied: types of interventions are Drug, Gene Transfer, Vaccine,
Behavior, Device, or Procedure.
INVESTIGATIONAL NEW DRUG: A new drug,
antibiotic drug, or biological drug that is used in a clinical investigation. It
also includes a biological product used in vitro for diagnostic purposes.
IRB: See Institutional
Review Board.
MASKED: The knowledge of intervention assignment.
See Blind
NATURAL HISTORY STUDY: Study of the natural
development of something (such as an organism or a disease) over a period of
time.
NEW DRUG APPLICATION (NDA): An application
submitted by the manufacturer of a drug to the FDA - after clinical trials have
been completed - for a license to market the drug for a specified indication.
OFF-LABEL USE: A drug prescribed for conditions
other than those approved by the FDA.
OPEN-LABEL TRIAL: A clinical trial in which
doctors and participants know which drug or vaccine is being administered.
ORPHAN DRUGS: An FDA category that refers to
medications used to treat diseases and conditions that occur rarely. There is
little financial incentive for the pharmaceutical industry to develop
medications for these diseases or conditions. Orphan drug status, however, gives
a manufacturer specific financial incentives to develop and provide such
medications.
PEER REVIEW: Review of a clinical trial by
experts chosen by the study sponsor. These experts review the trials for
scientific merit, participant safety, and ethical considerations.
PHARMACOKINETICS: The processes (in a
living organism) of absorption, distribution, metabolism, and excretion of a
drug or vaccine.
PHASE I TRIALS: Initial studies to determine
the metabolism and pharmacologic actions of drugs in humans, the side effects
associated with increasing doses, and to gain early evidence of effectiveness;
may include healthy participants and/or patients.
PHASE II TRIALS: Controlled clinical studies
conducted to evaluate the effectiveness of the drug for a particular indication
or indications in patients with the disease or condition under study and to
determine the common short-term side effects and risks.
PHASE III TRIALS: Expanded controlled and
uncontrolled trials after preliminary evidence suggesting effectiveness of the
drug has been obtained, and are intended to gather additional information to
evaluate the overall benefit-risk relationship of the drug and provide and
adequate basis for physician labeling.
PHASE IV TRIALS: Post-marketing studies to
delineate additional information including the drug's risks, benefits, and
optimal use.
PLACEBO: A placebo is an inactive pill,
liquid, or powder that has no treatment value. In clinical trials, experimental
treatments are often compared with placebos to assess the treatment's
effectiveness. In some studies, the participants in the control group will
receive a placebo instead of an active drug or treatment. No sick participant
receives a placebo if there is a known beneficial treatment. (See Placebo
Controlled Study).
PLACEBO CONTROLLED STUDY: A method of
investigation of drugs in which an inactive substance (the placebo) is given to
one group of participants, while the drug being tested is given to another
group. The results obtained in the two groups are then compared to see if the
investigational treatment is more effective in treating the condition.
PLACEBO EFFECT: A physical or emotional
change, occurring after a substance is taken or administered, that is not the
result of any special property of the substance. The change may be beneficial,
reflecting the expectations of the participant and, often, the expectations of
the person giving the substance.
PRECLINICAL: Refers to the testing of
experimental drugs in the test tube or in animals - the testing that occurs
before trials in humans may be carried out.
PREVENTION TRIALS: Refers to trials to find
better ways to prevent disease in people who have never had the disease or to
prevent a disease from returning. These approaches may include medicines,
vitamins, vaccines, minerals, or lifestyle changes.
PROTOCOL: A study plan on which all clinical
trials are based. The plan is carefully designed to safeguard the health of the
participants as well as answer specific research questions. A protocol describes
what types of people may participate in the trial; the schedule of tests,
procedures, medications, and dosages; and the length of the study. While in a
clinical trial, participants following a protocol are seen regularly by the
research staff to monitor their health and to determine the safety and
effectiveness of their treatment (See Inclusion/Exclusion
Criteria).
QUALITY OF LIFE TRIALS (or Supportive Care trials):
Refers to trials that explore ways to improve comfort and quality of
life for individuals with a chronic illness.
RANDOMIZATION: A method based on chance
by which study participants are assigned to a treatment group. Randomization
minimizes the differences among groups by equally distributing people with
particular characteristics among all the trial arms. The researchers do not know
which treatment is better. From what is known at the time, any one of the
treatments chosen could be of benefit to the participant (See Arm).
RANDOMIZED TRIAL: A study in which
participants are randomly (i.e., by chance) assigned to one of two or more
treatment arms of a clinical trial. Occasionally placebos are utilized. (See
Arm
and Placebo).
RISK-BENEFIT RATIO: The risk to individual
participants versus the potential benefits. The risk/benefit ratio may differ
depending on the condition being treated.
SCREENING TRIALS: Refers to trials which
test the best way to detect certain diseases or health conditions.
SIDE EFFECTS: Any undesired actions or effects of
a drug or treatment. Negative or adverse effects may include headache, nausea,
hair loss, skin irritation, or other physical problems. Experimental drugs must
be evaluated for both immediate and long-term side effects (See Adverse
Reaction).
SINGLE-BLIND STUDY: A study in which one party,
either the investigator or participant, is unaware of what medication the
participant is taking; also called single-masked study. (See Blind
and Double-Blind
Study).
SINGLE-MASKED STUDY: See Single-Blind
Study.
STANDARD TREATMENT: A treatment currently in
wide use and approved by the FDA, considered to be effective in the treatment of
a specific disease or condition.
STANDARDS OF CARE: Treatment regimen or
medical management based on state of the art participant care.
STATISTICAL SIGNIFICANCE: The probability
that an event or difference occurred by chance alone. In clinical trials, the
level of statistical significance depends on the number of participants studied
and the observations made, as well as the magnitude of differences observed.
STUDY ENDPOINT: A primary or secondary
outcome used to judge the effectiveness of a treatment.
STUDY TYPE: The primary investigative
techniques used in an observational protocol; types are Purpose, Duration,
Selection, and Timing.
TOXICITY: An adverse effect produced by a
drug that is detrimental to the participant's health. The level of toxicity
associated with a drug will vary depending on the condition which the drug is
used to treat.
TREATMENT IND: IND stands for Investigational New
Drug application, which is part of the process to get approval from the FDA for
marketing a new prescription drug in the U.S. It makes promising new drugs
available to desperately ill participants as early in the drug development
process as possible. Treatment INDs are made available to participants before
general marketing begins, typically during Phase III studies. To be considered
for a treatment IND a participant cannot be eligible to be in the definitive
clinical trial.
TREATMENT TRIALS: Refers to trials which test new
treatments, new combinations of drugs, or new approaches to surgery or radiation
therapy.
Glossary Sources:
AIDSinfo.Glossary of
HIV/AIDS-Related terms 4th Edition.
CenterWatch, Inc. Patient Resources: Glossary.
ECRI (formerly the Emergency Care Research Institute).
Eli Lilly and Company. Lilly Clinical Trials Glossary.
MediStudy.com Inc. ClinicalTrials: A-Z Glossary.
National Cancer Institute. Cancer.gov Dictionary.
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