What Are Clinical Trials?

Clinical trials are research studies in people to answer specific health questions (such as whether selenium and/or vitamin E can prevent prostate cancer, or whether intensive blood sugar control, blood pressure control, and cholesterol management can prevent heart problems in people with diabetes). Some research studies use participants with a particular illness or condition while others need healthy volunteers.

There are five types of clinical trials: treatment, prevention, diagnostic, screening, and quality of life. Treatment trials test new treatments and combinations of these treatments. Prevention trials look for ways to prevent disease from occurring or returning. Diagnostic trials seek better tests or procedures to diagnose a disease or condition. Screening trials test the best ways to detect a disease or condition. Quality of life trials study ways to improve quality of life in people with chronic illness.

Clinical trials are conducted in four phases:

1. In phase 1 studies, researchers test a new drug or treatment for the first time in people (20-80) to test its safety, find a proper dose, and identify side effects.
2. In phase 2, researchers give the study drug or treatment to people (100-300) with a disease or condition to see if it’s effective and further evaluate its safety.
3. Phase 3 clinical trials, which include 1,000-3,000 people, test the effectiveness and safety of a new drug or treatment compared to the current standard treatment or to a placebo. Subjects are assigned to receive the new drug/treatment or to the standard/placebo in a randomized manner, (similar to flipping a coin).
4. Phase 4 clinical trials collect more information on a drug or treatment after its approval in the United States by the Food and Drug Administration, including on the best way to use it and its risks and benefits.

Phase 3 clinical trials can also compare a new treatment to a standard treatment or a placebo (an inactive pill, liquid, or power that contains no medicine). The placebo or standard treatment is called a control. In controlled clinical trials, one group of patients receives the new drug or treatment and another group receives the control.

Participation in ALL clinical trials is voluntary, and you can leave a clinical trial at any time. Most clinical trials are sponsored by the federally-funded NIH and pharmaceutical and biotechnology companies. The NIH’s Clinicaltrials.gov Web site lists thousands of clinical trials. Academic medical centers such as Cooper University Hospital conduct hundreds of clinical trials each year. Other places for clinical trials include universities, medical schools, hospitals, and sometimes, doctors’ offices.