Clinical Trials Backgrounder
A clinical trial or clinical research is a research study in human volunteers to answer specific health questions.
Interventional trials determine whether experimental treatments or new ways of using known therapies are safe and effective
under controlled environments. Observational trials address health issues in large groups of people or populations in
Choosing to participate in a clinical trial is an important personal decision. The following frequently asked questions
will provide you with detailed information about clinical trials. In addition, it is often helpful to talk to your
health care provider, family members, or friends about deciding to join a trial. After you have identified some
trial options, the next step is to contact the study research staff and ask questions about specific trials
(Source: National Institute of Allergy and Infectious Diseases).
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What is a 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.
Ideas for clinical trials usually come from
researchers. Once researchers test new therapies or procedures in the laboratory and get
promising results, they begin planning Phase I clinical trials. New therapies are tested
on people only after laboratory and animal studies show promising results.
What is a protocol?
All clinical trials are based on a set of rules
called a protocol. 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 are seen regularly by the research staff to
monitor their health and to determine the safety and effectiveness of their treatment.
What are clinical trial phases?
Clinical trials of experimental drugs proceed through four phases:
- In Phase I clinical trials, researchers test a new
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 side effects.
- In Phase II clinical trials, the 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 studies, the 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 drug or treatment to be used safely.
- Phase IV studies are done after the drug or
treatment has been marketed. These studies continue testing the study drug or treatment to
collect information about their effect in various populations and any side effects
associated with long-term use.
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What protections are there for people who participate in clinical trials?
The government has strict guidelines and
safeguards to protect people who choose to participate in clinical trials. 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.
What is informed consent?
Informed consent is the process of learning the
key facts about a clinical trial before you decide whether or not to participate. These
- Why the research is being done.
- What the researchers want to accomplish.
- What will be done during the trial and for how long.
- What risks are involved in the trial.
- What benefits can be expected from the trial.
- What other treatments are available.
- The fact that you have the right to leave the trial at any time.
If you are considering joining a clinical trial,
the research staff will give you informed consent documents that include the details about
the study. If English is not your native language, you can ask for the consent documents
in languages other than English. Since joining a clinical trial is an important decision,
you should ask the research team any questions you may have about the study and the
consent forms before you make a decision.
It is also a good idea to take the consent
documents home and discuss them with family members or friends. Talking about your options
can help you to feel comfortable with your decision. If you decide to join the clinical
trial, be sure to ask for a copy of the informed consent documents so you can review them
at any time.
Remember informed consent is more than signing a
form. It is a process that continues through the study. You should feel free to ask the
research team questions before, during, and after the study. Informed consent continues as
long as you are in the study.
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Who can participate in a clinical trial?
All clinical trials have guidelines about who can
get into the program. Guidelines are based on such factors as age, type of disease,
medical history, and current medical condition. Before you join a clinical trial, you must
qualify for the study. Some research studies seek volunteers with illnesses or conditions
to be studied in the clinical trial, while others need healthy volunteers. Healthy
volunteers participate in Phase I trials, vaccine studies, and trials on research on
preventive care for children or adults.
The factors that allow you to participate in a
clinical trial are called inclusion criteria and the factors that keep you from
participating are called exclusion criteria. 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.
Who sponsorsclinical trials?
Clinical trials are sponsored by government
agencies: such as the National Institutes of Health (NIH); pharmaceutical companies;
individual physician- investigators; health care institutions such as health maintenance
organizations (HMOs); and organizations that develop medical devices or equipment. Trials
can take place in a variety of locations, such as hospitals, universities, doctors'
offices, or community clinics.
What happens during a clinical trial?
The clinical trial process depends on the kind of
trial you participate in. The team will include doctors and nurses as well as social
workers and other health care professionals. They will check your health at the beginning
of the trial, give you specific instructions for participating in the trial, monitor you
carefully during the trial, and stay in touch with you after the study.
Some clinical trials involve more tests and
doctor visits than you would normally have for your illness or condition. For all types of
trials, you will work with a research team. Your participation will be most successful if
you follow the protocol carefully and stay in contact with the research staff. Some terms
that will help you understand what happens in a trial are defined below.
What is a 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
What is a control or control group?
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.
What is a blinded or masked study?
A blinded or masked study is one in which
participants do not know whether they are in the experimental or control group in a
research study. Those in the experimental group get the medications or treatments being
tested, while those in the control group get a standard treatment or no treatment.
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What is a double-blind or double-masked study?
A double-blind or double-masked study is one in
which neither the participants nor the study staff know which participants are receiving
the experimental treatment and which ones are getting either a standard treatment or a
placebo. These studies are performed so neither the patients' nor the doctors'
expectations about the experimental drug can influence the outcome.
What are side effects and adverse reactions?
Side effects are any undesired actions or effects
of 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.
are the benefits and risks associated with clinical trials?
There are both benefits and risks associated with
clinical trials. By participating in a clinical trial, you can:
- Take an active role in your own health care.
- Gain access to new treatments that are not available to the public.
- Obtain expert medical care at leading health care facilities during the trial.
- Help others by contributing to medical research.
Clinical trials have risks:
- There may be side effects or adverse reactions to medications or treatments.
- The treatment may not be effective for you.
- The protocol may require a lot of your time for
trips to the study site, treatments, hospital stays, or complex dosage requirements.
What should I know before I join a clinical trial?
You should know as much as possible about the
research study. It is important for you to feel very comfortable asking questions and the
staff should answer them in a way you can understand. A list of sample questions appears
How should I prepare for the meeting with the research coordinator or doctor?
- Plan ahead and write down the questions you want to ask.
- Ask a friend or relative to come with you for support and to hear the responses to your questions.
- Bring a tape recorder so you can replay the discussion after you get home.
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What questions should I ask?
Some questions you might ask about the research include:
- Why is this research being done?
- What is the purpose of the study?
- Who has reviewed and approved this study?
- Why does the research team think the treatment,
drug, or medical device will work?
Some questions about your participation in the study include:
- Where is the study site?
- What kinds of therapies, procedures, and/or tests will I have during the trial?
- Will they hurt? If so, for how long?
- How will the tests in the study compare to tests I would have outside the study?
- How long will the study last?
- How often will I have to go to the study site?
- Who will provide my medical care after the study ends?
- Will I be able to take my regular medications during the trial?
- What medications, procedures, or treatments must I avoid while in the study?
- What are my responsibilities during the study?
- Will I have to be in the hospital during the study?
- Will the study researchers work with my doctor while I am in the study?
- Can anyone find out that I am participating in a study?
- Can I talk to other people in the study?
- Will I be able to find out the results of the trial?
Questions about risks and benefits include:
- How do the possible risks and benefits of the study compare with approved treatments for me?
- What are the possible immediate and long-term side effects?
Other questions include:
- What other treatment options do I have?
- Will I have to pay anything to participate in the study?
- What are the charges likely to be?
- Is my insurance likely to cover those expenses?
Should I continue working with my primary health
care provider if I participate in a trial?
Yes. Most clinical trials provide short-term
treatments related to a designated illness or condition, but not extended or complete
primary health care. In addition, by having your health care provider work with the
research team, you can ensure that your other medications or treatments will not conflict
with the clinical trial protocol.
Can I leave a clinical trial after it has begun?
Yes. You can leave a clinical trial at any time.
If you plan to stop participating, let the research team know why you are leaving the
Will I be paid for participating in a clinical trial?
Some clinical trials will pay you for joining the
trial, while others will not. In some programs, researchers will reimburse you for
expenses associated with participating in the research. Such expenses may include
transportation costs, child care, meals, and accommodations.
Institute of Allergy and Infectious Diseases, a division of the National Institutes of
Drug Development Process
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