Facts About Clinical Trials
Choosing to participate in a clinical trial is an important personal
decision. Participants need to educate themselves and ask many questions
before enrolling in a trial. They should also discuss the benefits and
risks of participating in a specific clinical trial with their physicians,
family and friends. Here are some resources to help with the decision-making
The National Institutes of Health's ClinicalTrials.gov
website includes an "Introduction
to Clinical Trials" with helpful questions and answers about
clinical trial participation. Selected Q & As from this website are
To find clinical trials for Parkinson's Disease that are currently
enrolling subjects, visit
PDtrials.org - specifically for Parkinson's Disease trials or
- a clinical trial registry for all conditions and diseases.
The next step is to contact the study research staff and ask
questions about their specific trial. Suggested questions are available
The Parkinson Pipeline Project is currently developing a "Bill of
Rights for Parkinson's Clinical Trial Participants." A draft version is
A clinical trial is a research study involving human volunteers to answer
specific health questions. It is the fastest and safest way to find treatments
that work in people and ways to improve health. Clinical trials compare the way
different groups of patients respond to different courses of treatment. A
controlled clinical trial compares patients receiving a course of treatment with
patients receiving no treatment (controls), to assess how much of an effect the
Participants 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 specific guidelines about who can participate. Using
inclusion/exclusion criteria 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
the clinical trial I qualify for and want to participate in is not within
driving distance of my home?
Most clinical trials are conducted at larger medical school or research facilities because of the need to follow a strict protocol and the expense involved in doing so. These facilities aren't always within driving distance for many patients. If you see a trial that interests you, but is being conducted far from home, call the contact person given and ask whether money is available to defray patients' travel expenses if this is a barrier to participation. The answer will help you make a better informed decision.
The clinical trial process depends on the kind of trial being conducted (See:
Types of clinical trials). A team of health care professionals checks
participants’ health at the beginning of the trial, gives specific instructions
for participating in the trial, monitors participants carefully during the
trial, and stays in touch after the trial is completed. Some trials involve more
tests and doctor visits than the participant would normally have. Clinical trial
participation is most successful when the protocol is carefully followed and
there is frequent contact with the research staff.
Treatment trials are the most common. They test new or alternative potential
treatments for specific diseases or medical conditions, new combinations of
drugs, or new approaches to surgery or radiation therapy.
Prevention trials seek 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.
Screening trials test new ways to detect specific diseases, especially
diseases that may have an early stage before they produce symptoms.
Diagnostic trials look for tests or procedures that could be used to identify
disease more accurately or at an earlier stage.
Genetics studies, sometimes part of another clinical trial, may focus on how
genetic makeup can affect detection, diagnosis, or response to treatment.
Quality of life (or Supportive Care) trials explore ways to improve comfort
and the quality of life for individuals with a chronic illness
Other types of medical research studies involve people but do not involve new
procedures. They range from experiments assessing the quality of new
questionnaires to tests of organ functions.
Clinical trials are conducted in phases, each of which has a different purpose
and helps scientists answer different questions:
In Phase I 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 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 trials, 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.
In Phase IV trials, post marketing studies delineate additional information
including the drug's risks, benefits, and optimal uses.
A protocol is a study plan designed to obtain answers to specific research
questions. It describes who may participate in the trial; the schedule of tests,
procedures, medications, and dosages; and the length of the study. During the
trial, the research staff regularly monitors the health of participants to
assess the safety and effectiveness of their treatment.
A placebo is an inactive pill, liquid, or powder that has no treatment value.
(See Placebo Effect). 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. Results are compared to
assess the new treatment's effectiveness.
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 that 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 patient
then decides whether or not to sign the document. Informed consent is not a
contract. The participant may withdraw from the trial at any time.
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.
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 protocol.
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, which details what researchers will do.
Center for Information & Study on Clinical Research Participation
An Introduction to Clinical Trials
National Institutes of Health.
NIH Fact Sheets Medical Research Clinical Trials