How Clinical Trials Work
A clinical trial is a kind of research that involves treatment and people. Clinical trials help researchers answer questions such as:
- Is a new treatment or medical device safe?
- Does the new treatment do what it is supposed to do?
- Is the new treatment better than a current treatment?
- Which patients benefit the most from the new treatment?
Clinical trials are done in steps called phases. At each phase, researchers try to answer a different question. Each phase needs a different set of participants, so a participant joins only one trial at a time.
The four phases of clinical trials
Phase I: Is it safe?
- This is the first time that a new treatment is tested with people so not many are included.
- The main goal is to see if the treatment is safe.
- People in Phase I studies can be healthy or have the disease.
Phase II: Does it work?
- Once a treatment is safe, then a Phase II study is done to see if the treatment works.
- Phase II studies usually have more participants than Phase I studies.
Phase III: Is it better than what we have now?
- A Phase III study compares a new treatment with a current treatment to see which is safer and works better.
- Phase III studies have large number of participants, sometimes thousands.
- After a Phase III study shows that a treatment works and is safe, then the Food and Drug Administration (FDA) reviews it for approval.
Phase IV: What else can happen?
- After FDA approval and the treatment is being used, researchers may do a Phase IV study.
- Phase IV studies look at whether the treatment is useful for other conditions or has long-term problems.
The two main types of clinical studies
Observational studies are where the researcher takes no study-related medical action. Patients are treated based on normal clinical decisions if needed. People in these studies are monitored over a period of time and the study team collects and looks at data about the participants.
Interventional clinical trials are where the researcher takes action to prevent, understand better or treat a disease. They test the safety and effectiveness of a new drug or other treatment. Interventional clinical trials follow strict rules to protect patients.