What is a Clinical Study?

As part of a major research center, we receive many questions about clinical studies. Some patients ask whether a new treatment can provide improvement for a disease that has compromised their vision. Others want to contribute to medical research that could lead to new and better treatments for their children or grandchildren.

Whatever your reason, it is a good idea to understand why the study is being conducted and what are the potential benefits and risks of participating.

Conducted under the supervision of a physician and other research professionals, a clinical study is a research study designed either to determine if a specific treatment — drug or medical device — is safe and effective or to compare more than one form of treatment with another. 

Clinical studies will recruit two or more groups of patient volunteers who are typically randomly assigned into the different arms of the study. In some clinical studies one group of patients may receive the new treatment and the other group may receive either the standard treatment or a placebo (dummy) drug.

By the time a drug, device, or other treatment is used in a clinical study, years of research have already taken place proving to scientists there is a good likelihood that patients will benefit from the new treatment and that the risks are low.

Several measures are in place to protect the safety of the patient and assure accuracy of results. Each study has a specific set of criteria defining who is eligible to enroll so that the findings are valid. Participants are given an informed consent document that describes the study in great detail, including potential risks and benefits. Clinical studies are run according to a carefully defined series of steps, called a protocol. Each person has ample time to ask questions before signing the consent.

Studies are funded by the National Institutes of Health, a funding agency, or a private company. They are governed by the Food and Drug Administration and may proceed through three phases:

Phase I studies
A Phase I study address safety only. These studies involve a small group of healthy people and determine how a drug should be given and what dose will be safe.
Phase II studies
The Phase II study continues monitoring safety but also begin to evaluate effectiveness of the drug, device, or procedure. These studies involve a larger group of people who have the disease or condition that is to be treated.
Phase III studies
A Phase III study usually compares a new drug, group of drugs, device, or procedure against the current standard treatment. These studies address effectiveness and require a large pool of volunteer subjects to assure the validity of the findings. To eliminate bias, each participant is randomly assigned either to the current standard treatment or to the alternative treatment by a coin toss or by computer. Many Phase III studies are conducted nationwide, each center following the same stringent protocol to test the new treatment over a large and diverse population.