A clinical trial is a prospective study of the effectiveness of a new treatment, such as a drug, surgical technique, or medical device. The term prospective indicates that there is a well-defined starting point from which the subjects are tracked for some definite period of time. Before a clinical trial is conducted, laboratory experimentation and animal trials on the proposed treatment is performed.
Clinical trials must meet strict government guidelines established by the U. S. Food and Drug Administration (FDA) to assure the safety of subjects and the scientific validity of the trial. Prior to admission to a clinical trial, subjects must meet the study requirements and be sufficiently informed regarding the purpose of the trial. A new treatment may have major benefits but may also have significant side effects for the type of patient that it could help. Careful screening and examination help select persons who meet the trial's design and intent. Informed consent, required of all participants, will alert the subjects not only to the purpose and design of trial with its potential benefits but to any known or suspected side effects or complications.
A phase I trial is a small-scale test in healthy volunteers to determine the general safety of the treatment with human subjects. Phase II tests the safety and effectiveness of the new treatment in a small group of patients who might benefit. A phase III trial is a large-scale study to scientifically document the value of the proposed drug, technique, or device. Phase IV studies allow the long-term follow-up of patients to determine side effects and continued effectiveness after a treatment reaches the market.
The expense involved in clinical trials is due to the extensive development and research costs, initial laboratory testing, and their large-scale nature. Conducted at multiple sites around the country, clinical trials have significant infrastructure for record-keeping, follow-up, dissemination, and safety.
Friedman, L. M., C. D. Furberg, and D. L. DeMets. Fundamentals of Clinical Trials, 3rd ed. New York: Springer-Verlag, 1998.
Whitehead, John. The Design and Analysis of Sequential Clinical Trials, 2nd ed. New York: John Wiley & Sons, 1997.