Learn About Clinical Studies


What is a clinical study?

A clinical study, also called a clinical trial, looks at new ways to prevent, detect, or treat disease. Often the goal of a clinical study is to determine if a new treatment works and is safe. Studies can also look at other aspects of care, such as improving the quality of life for people with chronic illnesses.

Every clinical study is led by a principal investigator, a medical doctor. Clinical studies also have a research team that may include doctors, nurses, social workers, and other healthcare professionals.

Clinical studies provide additional options for many people and an opportunity to help researchers find better treatments for others in the future.

Phases of a clinical study

The development of an investigational treatment is conducted in phases. Each phase has a different purpose and helps researchers answer different questions. Size ranges are approximate. All phases are investigational and a drug or treatment may not move to the next phase. The development of a drug may not progress through all phases.

  • Phase I trials: Researchers test an experimental drug or treatment in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.
  • Phase II trials: The experimental drug or treatment is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.
  • Phase III trials: The experimental drug or treatment is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments, and collect information that will allow the experimental drug or treatment to be used safely.
  • Phase IV trials: If a drug is approved by the FDA and made available to the public, researchers track its safety, seeking more information about a drug or treatment’s risks, benefits, and optimal use.

Source: National Institutes of Health

Participating in a clinical study

Participants may choose to participate in a study to help others, but also to possibly receive an investigational treatment.

Taking part in this study may or may not make your health better. Most trials involve some risk of harm or injury. If you are interested in joining this study, discuss these issues with members of the research team and with your healthcare provider. If you agree to participate, you will be required to sign an Informed Consent Form (ICF). The ICF contains information about the study, which your doctor will explain so you can decide if you want to participate.

Remember, you may withdraw from a study at any time, even if the study is not over.

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