Glossary of Clinical Trials Terms
The following glossary was prepared to help the consumer become familiar
with the most common terms used in clinical studies:

ADVERSE REACTION: (Adverse Event.) An unwanted effect caused by the
administration of drugs. Onset may be sudden or develop over time.

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

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 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

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

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.

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:

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

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

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.

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

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

INTERVENTIONS: Primary interventions being studied: types of
interventions are Drug, Gene Transfer, Vaccine, Behavior, Device, or

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. (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

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.

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

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

TREATMENT TRIALS:Refers to trials which test new treatments, new
combinations of drugs, or new approaches to surgery or radiation therapy.