Choosing to participate in a clinical trial is an important personal decision.
The following frequently asked questions provide detailed
information about clinical trials. In addition, it is often helpful to talk
to a physician, family members, or friends about deciding to join a trial.
After identifying some trial options, the next step is to contact the
study research staff and ask questions about specific trials.
Although there are many definitions of clinical trials, they are
generally considered to be biomedical or health-related research studies
in human beings that follow a pre-defined protocol.
ClinicalTrials.gov includes both interventional and observational types of studies.
Interventional studies are those in which the research subjects are assigned by
the investigator to a treatment or other intervention, and their outcomes are
measured. Observational studies are those in which individuals are observed
and their outcomes are measured by the investigators.
Participants in clinical trials can play a more active role in their own health care,
gain access to new research treatments before they are widely available,
and help others by contributing to medical research.
All clinical trials have guidelines about who can participate.
Using inclusion/exclusion criteria
is an important
principle of medical research that helps to produce reliable results. The
factors that allow someone to participate in a clinical trial are called "inclusion
criteria" and those that disallow someone from participating are called "exclusion
criteria". These criteria are based
on such factors as age, gender, the type and stage of a disease, previous
treatment history, and other medical conditions. Before joining a clinical
trial, a participant must qualify for the study. Some research studies seek participants with illnesses or
conditions to be studied in the clinical trial, while others need healthy participants.
It is important to note that inclusion and exclusion criteria are not used to
reject people personally. Instead, the criteria are used to identify
appropriate participants and keep them safe. The criteria help ensure that
researchers will be able to answer the questions they plan to study.
The clinical trial process depends on the kind of trial
being conducted (See What are the different types of clinical trials?
The clinical trial team includes doctors and nurses as
well as social workers and other health care professionals. They check the
health of the participant at the beginning of the trial, give specific
instructions for participating in the trial, monitor the participant carefully
during the trial, and stay in touch after the trial is completed.
Some clinical trials involve more tests and doctor visits than the participant
would normally have for an illness or condition. For all types of trials, the participant
works with a research team. Clinical trial participation is most successful when
is carefully followed
and there is frequent contact with the research staff.
Informed consent is 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. If the participant's native language is
not English, translation assistance can be provided. Then the research team provides
an informed consent document
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.
Clinical trials that are well-designed and well-executed are the best approach
for eligible participants to:
- Play an active role in their own health care.
- Gain access to new research treatments before they are widely available.
- Obtain expert medical care at leading health care facilities during the trial.
- Help others by contributing to medical research.
There are risks to clinical trials.
- There may be unpleasant, serious or even life-threatening side effects to experimental treatment.
- The experimental treatment may not be effective for the participant.
- The protocol may require more of their time
and attention than would a non-protocol treatment, including trips to the study site, more treatments,
hospital stays or complex dosage requirements.
Side effects are any undesired actions or effects of the experimental drug or
treatment. Negative or adverse effects may include headache, nausea, hair loss,
skin irritation, or other physical problems. Experimental treatments must be
evaluated for both immediate and long-term side effects.
The ethical and legal codes that govern medical practice also apply to clinical trials. In addition,
most clinical research is federally regulated with built in safeguards to protect the participants.
The trial follows a carefully controlled protocol, a study plan which details what researchers will do
in the study. As a clinical trial progresses, researchers report the results of the trial at scientific
meetings, to medical journals, and to various government agencies. Individual participants' names will
remain secret and will not be mentioned in these reports
(See Confidentiality Regarding Trial Participants
People should know as much as possible about the clinical trial and feel comfortable
asking the members of the health care team questions about it, the care expected
while in a trial, and the cost of the trial. The following questions might be helpful
for the participant to discuss with the health care team. Some of the answers to these
questions are found in the informed consent document.
- What is the purpose of the study?
- Who is going to be in the study?
- Why do researchers believe the experimental treatment being tested may be effective? Has it been tested before?
- What kinds of tests and experimental treatments are involved?
- How do the possible risks, side effects, and benefits in the study compare with my current treatment?
- How might this trial affect my daily life?
- How long will the trial last?
- Will hospitalization be required?
- Who will pay for the experimental treatment?
- Will I be reimbursed for other expenses?
- What type of long-term follow up care is part of this study?
- How will I know that the experimental treatment is working? Will results of the trials be provided to me?
- Who will be in charge of my care?
- Plan ahead and write down possible questions to ask.
- Ask a friend or relative to come along for support and to hear the responses to the questions.
- Bring a tape recorder to record the discussion to replay later.
Every clinical trial in the U.S. must be approved and monitored by an
Institutional Review Board (IRB)
to make sure the risks are as low as possible and are worth any potential benefits.
An IRB is an independent committee of physicians, statisticians, community advocates,
and others that ensures that a clinical trial is ethical and the rights of study
participants are protected. All institutions that conduct or support biomedical
research involving people must, by federal regulation, have an IRB that initially
approves and periodically reviews the research.
Yes. Most clinical trials provide short-term treatments
related to a designated illness or condition, but do not provide extended or
complete primary health care. In addition, by having the health care provider
work with the research team, the participant can ensure that other medications
or treatments will not conflict with the
Yes. A participant can leave a clinical trial, at any time.
When withdrawing from the trial, the participant should let the research team
know about it, and the reasons for leaving the study.
Ideas for clinical trials usually come from researchers. After researchers test
new therapies or procedures in the laboratory and in animal studies, the experimental
treatments with the most promising laboratory results are moved into clinical trials.
During a trial, more and more information is gained about an experimental treatment,
its risks and how well it may or may not work.
Clinical trials are sponsored or funded by a variety of organizations or individuals
such as physicians, medical institutions, foundations, voluntary groups, and pharmaceutical
companies, in addition to federal agencies such as the National Institutes of Health (NIH),
the Department of Defense (DOD), and the Department of Veteran's Affairs (VA). Trials can
take place in a variety of locations, such as hospitals, universities, doctors' offices, or
A protocol is 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.
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 experimental treatment's effectiveness. In some studies, the participants
in the control group
a placebo instead of an active drug or experimental treatment.
A control is 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.
test experimental treatments, new combinations of drugs, or new approaches to
surgery or radiation therapy.
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, vaccines, vitamins,
minerals, or lifestyle changes.
to find better tests or procedures for diagnosing a particular disease or condition.
test the best
way to detect certain diseases or health conditions.
Quality of Life trials
(or Supportive Care trials) explore ways to improve comfort and the quality of
life for individuals with a chronic illness.
Clinical trials are conducted in phases. The trials at each phase have a different
purpose and help scientists answer different questions:
In Phase I trials
test an experimental drug or treatment in a small group of people (20-80) for the
first time to evaluate its safety, determine a safe dosage range, and identify
In Phase II trials
experimental study drug or treatment is given to a larger group of people
(100-300) to see if it is effective and to further evaluate its safety.
In Phase III trials
experimental study drug or treatment is given to large groups of people
(1,000-3,000) to confirm its effectiveness, monitor side effects, compare it
to commonly used treatments, and collect information that will allow the
experimental drug or treatment to be used safely.
In Phase IV trials
marketing studies delineate additional information including the drug's risks,
benefits, and optimal use.
Expanded access is a means by which manufacturers make
investigational new drugs
under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot
participate in a controlled clinical trial
Most human use of investigational new drugs
takes place in controlled clinical trials conducted to assess the safety and
of new drugs. Data from these trials
are used to determine whether a drug is safe and effective, and serve as the basis for the drug marketing
application. Sometimes, patients do not qualify for these controlled trials because of other health
problems, age, or other factors, or are otherwise unable to enroll in such trials (e.g., a patient
may not live sufficiently close to a clinical trial site).
For patients who cannot participate in a clinical trial of an investigational drug, but have a
serious disease or condition that may benefit from treatment with the drug,
regulations enable manufacturers of such drugs
to provide those patients access to the drug under certain situations, known as "expanded access."
For example, the drug cannot expose patients to unreasonable risks given the severity of the disease
to be treated and the patient does not have any other satisfactory therapeutic options (e.g., an
approved drug that could be used to treat the patient's disease or condition). The manufacturer must
be willing to make the drug available for expanded access use. The primary intent of expanded access
is to provide treatment for a patient's disease or condition, rather than to collect data about the
Some investigational drugs are available for treatment use from pharmaceutical manufacturers through
expanded access programs listed in ClinicalTrials.gov. If you or a loved one is interested in treatment
with an investigational drug under an expanded access protocol listed in ClinicalTrials.gov, review the
protocol eligibility criteria and inquire at the Contact Information number. If there is not an expanded
access protocol listed in ClinicalTrials.gov, you or your health care provider may contact a manufacturer
of an investigational drug directly to ask about expanded access programs.
For additional information on expanded access programs, please see the FDA website at
Access to Investigational Drugs
Expanded Access Studies can be found by in ClinicalTrials.gov:
- go to the Advanced Search page,
- select "Expanded Access Studies" from the "Study Type" pull-down menu, and
- press Search.
or use these prepared links: