A clinical trial is a type of research. Research is the process scientists use to discover how our bodies work or why our bodies stop working well. Clinical trials are studies that help doctors learn whether a new drug, device, surgery, diet change, lab test, imaging technique, treatment method, or type of education is safe and works well in humans.1-3
Clinical trials lead to better healthcare and longer, healthier lives.
Types of clinical trials
There are several types of clinical trials. These trials can be described by the type or phase of research, such as:1
Behavioral trials look at whether a change in how a person behaves improves their health. The change might be in diet, exercise, social support, or mental health.
Diagnostic trials look at how a disease is diagnosed. These studies often try to find out whether new tests are more accurate or faster at finding a health problem.
Interventional study is another name for a clinical trial. A clinical trial examines whether an intervention works. An intervention may be a new drug, device, surgery, test, or activity.
Observational studies do not change or test treatment, but instead monitor study participants to evaluate certain outcomes. A questionnaire or a survey that asks questions about a drug or the side effects of surgery are examples of observational studies.
Prevention trials test whether new drugs, vaccines, or lifestyle changes prevent a disease from occurring for the first time or from returning.
Quality-of-life trials look at ways to improve quality of life for people with a certain health condition.
Screening trials test new ways to find diseases.
Treatment trials test new drugs, devices, surgeries, and other treatments to see whether they are safe and how well they work. These new treatments also may be compared with existing standard treatments or a placebo. Or they may be combined with other treatments to see which works the best.
Clinical trial phases
The process to approve a treatment for use in humans can take years. Many new treatments are tested first in a lab, sometimes on animals other than humans.1-3
If the treatment looks promising, the treatment will then move on to being tested on humans. This testing takes place in stages, and in the United States it must follow rules set by the Food and Drug Administration (FDA).1-3
Clinical trials run in 4 stages, or phases:1
- Phase 1: A very small group of people take a new drug or device for the first time to look at safety, dosage range, and side effects. Fewer than 25 people may be involved in a phase 1 trial.
- Phase 2: A larger group takes the drug to see how well it works and whether it is still safe. The number of participants varies, but a phase 2 trial may include between 50 and 300 people.
- Phase 3: At this point, the drug or device is thought to be safe enough to give to a large group of people. A few hundred to a few thousand people may be using the drug or device at this point. Doctors continue to look for side effects and focus on how well the treatment works. Sometimes a new treatment is compared to other drugs.
- Phase 4: The FDA has now approved the treatment, and it is now available to the public. Researchers continue to gather data about how the drug works in a larger, more diverse population. They also look for new or different side effects that may come up with long-term use.
Is medical research safe?
All medical research on humans must be approved and monitored by a group of scientists, researchers, and doctors called an institutional review board (IRB). IRBs must follow rules for human safety laid out by the FDA.1,3
If a new treatment appears to be unsafe at any stage, the clinical trial may be stopped. The researchers involved then explain what they think went wrong. Often, any medical care related to the trial is provided at no cost because it is experimental.1,3
IRBs and FDA regulations exist to make medical studies as safe as possible for people to join. However, all research has risks. Some risks are predictable and some are not. That is why something called informed consent is so important.4
What is informed consent?
Informed consent is the process of making sure a person joining a clinical trial understands the details of participation, including the potential risks and benefits of that study. Informed consent includes making sure the person understands what they will need to do to join the study and that they can stop participating in the study at any time. An informed consent form outlines all of this information.4
Who pays for research?
There are a few main sources of funding for health research. The federal government, nonprofits, universities, and pharmaceutical companies all fund research.3
Where do studies take place?
Clinical trials typically take place in hospitals, doctor’s offices, universities, and clinics. Often, a clinical trial will include people from many cities, states, and countries. For the most part, clinical trials are located in major cities.1-3
How to get involved
Joining a clinical trial lets you contribute to your community by sharing your unique health and responses to treatments. To find a study that is right for you, talk to your doctor or visit the US government’s clinical trial registry at ClinicalTrials.gov.
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