Thinking of a Clinical Trial? What You Need to Know

Medical Author: Melissa Stoppler, M.D.
Medical Editor: Barbara K. Hecht, Ph.D.

Today it is hard to find a medical news story without mention of a clinical trial. What exactly is a clinical trial? A clinical trial is a research study that involves human participants in order to answer specific health questions.

Who can participate in a clinical trial? Can you? A relative? A friend? It all depends. There are guidelines spelled out ahead of time as to who will be eligible to enter a specific clinical trial. A participant must qualify and then be enrolled in the trial.

To participate in a clinical trial, the individual must do so voluntarily, have the trial explained in detail to them and give their informed consent to participate. Clinical trials are never conducted without the knowledge and agreement of those taking part.

Different types of clinical trials are designed to address different questions. Most clinical trials fall into the following categories:

  • Treatment trials -- to test new drugs, combinations of drugs, or new procedures and approaches to treating a particular condition.
  • Prevention trials -- to study methods in which one can prevent disease from developing.
  • Diagnostic trials -- to look for improved tests to diagnose a specific condition.
  • Screening trials -- to look for the best ways to test a population for the incidence of a specific disease.
  • Quality of life trials -- to find ways to increase and improve the quality of life for patients with a chronic or progressive disease.

Clinical trials take place in hospitals, universities, private clinics, and community health centers. They may be sponsored by federal agencies such as the National Institutes of Health (NIH), nongovernmental foundation, or companies such medical drug and device manufacturers.

Clinical trials are regulated by what are called Institutional Review Boards (IRBs) at the hospitals or other facilities where the trial is to take place. All institutions involved with biomedical research on human subjects are required by law to have an independent IRB to ensure that a clinical trial does not violate ethical principles and that participants' rights are protected.

Clinical trials follow carefully designed plans, or protocols, that ensure uniformity throughout the research study. Clinical trials run in planned phases with different goals. For example, a clinical trial to test a new drug developed in the laboratory might include the following phases:

  • Phase I -- to test the drug in a small group (20-80 people) to determine its safety, dosage, and side effects.
  • Phase II -- to test the drug with an expanded group (100-300 people) to collect more information about a new drug's efficacy and risks.
  • Phase III -- the drug is given to an even larger group (1000-3000 people) to monitor use of the drug, compare it to other treatments, and further ensure its safety.
  • Phase IV -- post-marketing studies that begin as soon as the drug is approved to further study the benefits and risks of the drug.

Clinical trials are constantly monitored and are stopped if it is discovered that the participants' health is at undue risk by their continued participation in the trial. Likewise, clinical trial participants can choose to withdraw from a clinical trial at any time.

If you are interested in learning more about the available clinical trials or in participating in one, the NIH site www.ClinicalTrials.gov provides updated information about federally and privately sponsored clinical trials.


Last Editorial Review: 3/29/2005




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