|Clinical trials are research studies designed to answer specific questions about the effects of drugs, vaccines, medical devices, tests, treatments, and other therapies for patients. Clinical trials are used to determine safety and effectiveness.|
The National Institutes of Health (NIH) categorizes human clinical trials into the following four phases. Phase I through III are included in the data reported on the survey, Phase IV is excluded.
- Phase I uses a small group of human patients (20-80) to evaluate safety and identify side effects.
- Phase II uses a larger group (100-300) to test effectiveness and further evaluate safety.
- Phase III uses a large group (1,000-3,000) to confirm effectiveness, monitor side effects, compare to commonly used treatments, and collect safety information.
- Phase IV is a post-market study that collects more information on risks, benefits, and optimal use.