Clinical Trials

Choosing to participate in a clinical trial is an important personal decision. The following frequently asked questions will provide you with information about clinical trials.

What is a clinical trial? 
What is a protocol? 
What are clinical trial phases? 
What protections are there for people who participate in clinical trials? 
What is informed consent? 
Who can participate in a clinical trial? 
Who sponsors clinical trials? 
What happens during a clinical trial? 
What is a placebo? 
What is a control or control group? 
What is a blinded or masked study? 
What is a double-blind or double-masked study? 
What are side effects and adverse reactions? 
What are the benefits and risks associated with clinical trials? 
Can I leave a clinical trial after it has begun?


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.

Once researchers test new therapies or procedures in the laboratory and get promising results, they begin planning Phase 1 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 the treatment.


What are clinical trial phases?
Clinical trials of experimental drugs proceed through four phases:

  • In Phase 1 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 2 clinical trials, the study drug or treatment is given to a larger group of people (40-100) to see if it is effective and to further evaluate its safety.

  • In Phase 3 studies, the study drug or treatment is given to large groups of people (more than 200) to further determine 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 4 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.


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 United States 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. By federal regulation, all institutions that conduct or support biomedical research involving people must 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 facts include:

  • Why the research is being done
  • What does 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. Because 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.


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 1 trials, some 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 sponsors clinical trials?
Clinical trials are sponsored by government agencies such as the National Institutes of Health; pharmaceutical and biotechnology 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 in which you participate. 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.


What is a placebo?
A placebo is an inactive substance 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 treatment.


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, and 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, and those in the control group get a standard treatment or no treatment.


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 receiving either a standard treatment or a placebo. These studies are performed so that 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.


What 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


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 study.

Adapted from “What Is a Clinical Trial?” by the National Institutes of Health, available atwww.clinicaltrials.gov

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