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Clinical Trial FAQ

Research Institute

What is a clinical trial?

A clinical trial is a medical research study in which people participate as volunteers to test many types of therapies such as new drugs or medical devices. The goal of these clinical research studies is to answer important questions about medical care in an effort to develop new and improved ways to treat all patients with and those who will develop in the future.

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Why are clinical trials important?

Patients choose to participate in a clinical trial for many reasons.

  • First, the therapy patients on clinical trials receive may be effective in fighting their particular medical condition. In a clinical trial, patients will receive the current standard of care treatment or a new drug, procedure, or device which is being studied. By participating in a clinical trial, patients are given access to the latest available treatments. There is no guarantee that these new treatments will be effective. However, many clinical trial participants decide that the potential benefits of the new treatment outweigh the risks.
  • Second, clinical trials are the most important tool that doctor-researchers have in their effort to find new and more effective ways to treat and possibly cure various medical conditions. Many of today’s medical treatments began in clinical trials.
  • Third, many patients feel that participating in a clinical trial can be empowering because it allows them to take an active role in their treatment options. They also know their participation in a trial might be helping to find a new treatment or cure.
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Why participate in a clinical trial?

Participants in clinical trials can play a more active role in their own health care by gaining access to new research treatments before they are widely available. Participating in clinical trials can help others and future generations by contributing to medical research and advancing patient care.

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Who can participate in a clinical trial?

Taking part in a clinical trial is voluntary. However, all clinical trials have guidelines about who can and cannot participate. Meeting inclusion and exclusion criteria is an important principle of clinical 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 do not allow someone to participate are called "exclusion criteria." These criteria are based on such factors as age, the type and stage of a disease, previous treatment history, and other medical conditions. Before enrolling into 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. These criteria help ensure that researchers will be able to answer the questions they plan to study, while ensuring that all measures to maintain efficacy, safety and equity exists.

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Who pays for the patient care costs?

Usually a patient’s insurance will cover all standard of care treatments such as exams, laboratory work, X-ray, etc. (standard of care is the routine care provided for a disease). All additional clinical trial related therapies or laboratory studies may be paid for by the sponsor of the clinical trial, such as a pharmaceutical company. Patients should ask their doctor what is covered by their insurance to ensure that their out-of-pocket costs have been explained to fully.

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What happens during a clinical trial?

The clinical trial team includes doctors, nurses and other health care professionals. They check the health of participants during the trial, give specific instructions for participating in the trial and guide them through the process. They monitor the participants 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 closely with the research team. Clinical trial participation is most successful when the study guidelines are carefully followed and there is frequent contact with the research staff.

If the doctor-researcher determines that a therapy is harmful to you, you will be taken off of the study immediately. You may then receive other treatments from your own doctor.

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What is informed consent?

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 will be provided. The research team provides a consent document that includes details about the study, such as its purpose, how long it will last, required procedures and key contacts. Risks and potential benefits are explained in the consent document. The participant then decides whether or not to sign the document. Participation in any trial is completely voluntary. Informed consent is not a contract and the participant may withdraw from the trial at any time.

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What are the benefits and risks of participating in a clinical trial?


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 decision process along with their provider.
  • Gain access to new research therapies 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.

  • The risks and side effects to each research treatment are outlined for each trial and can vary from trial to trial. Your doctor and study coordinator will review with you all the risks that are specific to that trial or other physical problems that the doctor does not expect or desire.
  • There may be unpleasant, serious or even life-threatening side effects to experimental therapy, such as headaches, nausea, hair loss, skin irritation or other physical problems the doctor does not expect or desire.
  • In clinical trials, the research treatment may not be effective for the participant.
  • The clinical trial may require more of your time and attention than would standard of care treatment, including trips to Phoenix Children's, more hospital stays, or complex dosage requirements.
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How is the safety of the participant protected?

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 ensure that a clinical trial is ethical and the rights of study participants are protected. All institutions that conduct or support biomedical research involving people (human participants) must, by federal regulation, have an IRB that initially approves and periodically (continually) reviews the research (for side effects) to ensure participant safety.

Once the trial is approved by the IRB, the participants enrolled in the study follow a carefully controlled protocol and study plan which details what researchers will do throughout the study. 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.

As a clinical trial progresses, researchers report the results of the trial at scientific meetings, to medical journals, and to various government agencies. The names of participants remain secret and are not mentioned in these reports.

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What should people consider before participating in a clinical trial?

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 therapy being tested may be effective? Has it been tested before?
  • What kinds of tests and experimental therapy(ies) are involved?
  • How do the possible risks, side effects, and benefits in the study compare with my current treatment?
  • How might this clinical trial affect my daily life?
  • How long will the clinical trial last?
  • Will hospitalization be required?
  • Who will pay for the experimental drug(s) or device?
  • Will I be reimbursed for other expenses?
  • What type of long-term follow-up care is required for this study?
  • How will I know that the experimental therapy is working? Will results of the trials be provided to me?
  • Who will be in charge of my care?
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What kind of preparation should a potential participant make for the meeting with the study coordinator or doctor?

  • 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.
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Does a participant continue to work with a primary health care provider while in a trial?

Yes. Most clinical trials provide short-term therapies 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.

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Can a participant leave a clinical trial after it has begun?

Yes. A participant can leave a clinical trial, at any time. When withdrawing from the clinical trial, the participant should let the research team know about it, and the reasons for leaving the study.

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What are the different types of clinical trials?

  1. Treatment trials test new therapies (like a new drugs, new approaches to surgery, or medical devices).
  2. Prevention trials test new approaches, such as medicines, vitamins, minerals or other supplements that doctors believe may lower the risk of certain medical conditions. These trials look for the best way to prevent medical conditions for patients who have never had them. They also look at how to prevent medical conditions from coming back or a new condition.
  3. Screening trials test the best way to find certain medical conditions such as cancer, especially in its early stages.
  4. Quality of Life trials explore ways to improve comfort and quality of life for patients.
  5. Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular medical condition.
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What are the different phases of clinical trials?

Most clinical research involves the testing of a new drug in steps, called phases. This allows researchers to ask and answer questions in a way that results in reliable information about the drug and protects the participants. Clinical trials are usually classified into one of three phases:

  1. Phase I trials are the first step in testing a new therapy in humans. In these studies, researchers evaluate how a new drug should be given (by mouth, injected into the blood or injected into the muscle), how often, and what dose is safe. A Phase I trial usually enrolls only a small number of participants, sometimes as few as a dozen.
  2. Phase II trials focus on evaluating how well the new drug works and continues to test the safety of the drug. Phase II studies usually focus on a particular type of.
  3. Phase III trials compare the results of people taking the new therapy with results of people taking standard or care treatment. A participant will usually be assigned to the standard treatment group or the new clinical trial therapy group at random (called randomization). Phase III trials often enroll large numbers of participants and may be conducted at many doctors' offices, clinics, and research institutions nationwide.
  4. Phase IV trials examine the treatment after it has been approved and is being marketed. Phase IV trials evaluate the side effects, risks, and benefits of a drug over a longer period of time and in a larger number of participants than in phase III clinical trials. Thousands of people are involved in a phase IV trial.
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Who sponsors clinical trials?

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 Veterans Affairs (VA). Trials can take place in a variety of locations, such as hospitals, universities, doctors' offices or community clinics.

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