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 healthcare 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. To search the National Library of Medicine's clinical trials database and locate clinical trials investigating Alzheimer's disease, click here.
What is a clinical trial?
A clinical trial is a research study involving human subjects 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. Pre-clinical trials typically study the actions of potential treatments in laboratory culture dishes or test tubes - called in vitro studies - or in laboratory animals such as mice, rats or monkeys. 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 to 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 to 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 to 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.
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. The "institution" in IRB is usually a university or a hospital.
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 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 throughout 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.
People suffering from Alzheimer's disease may not be mentally capable of giving consent, in which case the consent process must be conducted by next-of-kin or a person granted power of attorney.
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 sponsors clinical 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 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.
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.
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