In a clinical trial, participants receive specific interventions according to the research plan or protocol created by the investigators. These interventions may be medical products, such as drugs or devices; procedures; or changes to participants' behavior, such as diet. Clinical trials may compare a new medical approach to a standard one that is already available, to a placebo that contains no active ingredients, or to no intervention. Some clinical trials compare interventions that are already available to each other.
What are the Phases of Clinical Trials?
Phase 1: Consists of 20 to 100 healthy volunteers or people with the disease/condition. This phase lasts several months with the purpose of evaluating safety and tolerated dosage. Approximately 70% of drugs move to the next phase.
Phase 2: Consists of several hundred volunteers with the disease/condition. This phase lasts anywhere from several months to 2 years with the purpose of evaluating effectiveness and side effects. Approximately 33% of drugs move to the next phase.
Phase 3: Consists of several hundred or several thousand volunteers who have the disease or condition. This phase lasts anywhere from 1 to 4 years with the purpose of evaluating effectiveness and adverse reactions.
Phase 4: Consists of several thousand volunteers who have the condition. This is a post-market study and does not have a set time-frame. The purpose of this phase is to continuously monitor for safety and effectiveness.
Who Conducts Clinical Trials?
Every clinical study is led by a principal investigator, who is often a medical doctor. Clinical studies also have a research team that may include doctors, nurses, social workers, and other health care professionals. Clinical studies can be sponsored, or funded, by pharmaceutical companies, academic medical centers, voluntary groups, and other organizations, in addition to Federal agencies such as the National Institutes of Health, the U.S. Department of Defense, and the U.S. Department of Veterans Affairs. Doctors, other health care providers, and other individuals can also sponsor clinical research.
Who Can Participate in Clinical Trials?
Clinical studies have standards outlining who can participate. These standards are called eligibility criteria and are listed in the protocol. Some research studies seek participants who have the illnesses or conditions that will be studied, other studies are looking for healthy participants, and some studies are limited to a predetermined group of people who are asked by researchers to enroll.
How are Participants Protected?
Informed consent is a process used by researchers to provide potential and enrolled participants with information about a clinical study. This information helps people decide whether they want to enroll or continue to participate in the study. The informed consent process is intended to protect participants and should provide enough information for a person to understand the risks of, potential benefits of, and alternatives to the study. Participants may withdraw from a study at any time, even if the study is not over.
Questions to Ask Your Research Team:
What is being studied?
Why do researchers believe the intervention being tested might be effective? Why might it not be effective? Has it been tested before?
What are the possible interventions that I might receive during the trial?
How will it be determined which interventions I receive (for example, by chance)?
Who will know which intervention I receive during the trial? Will I know? Will members of the research team know?
How do the possible risks, side effects, and benefits of this trial compare with those of my current treatment?
What will I have to do?
What tests and procedures are involved?
How often will I have to visit the hospital or clinic?
Will hospitalization be required?
How long will the study last?
Who will pay for my participation?
Will I be reimbursed for other expenses?
What type of long-term follow-up care is part of this trial?
If I benefit from the intervention, will I be allowed to continue receiving it after the trial ends?
Will results of the study be provided to me?
Who will oversee my medical care while I am participating in the trial?
What are my options if I am injured during the study?