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...know how to do them and they were rampant with problems, says Robert Temple, M.D., director of the FDA's Office of Medical Policy. Over the years, FDA experts evaluated the many shortcomings of the clinical trials they saw and worked to fix them. To this end, the FDA established regulations and guidance to ensure that sponsors of clinical trials, medical researchers (investigators), and ethics committees (institutional review boards) understand how they can effectively carry out their responsibilities and comply with federal law.
"As FDA expertise evolved, so did controlled clinical trials, and the quality of their design, conduct, analysis, and interpretation improved," says Robert T. O'Neill, Ph.D., director of the FDA's Office of Biostatistics, who has seen much of the evolution of controlled trials since he joined the FDA in 1971. "FDA has been the major force behind the development of good principles for the design and interpretation of controlled trials. We've promoted, fed, and cared for controlled clinical trials as critical force in drug development, and we continue to do so today."
What Is a Controlled Clinical Trial?
A clinical trial uses an investigational product in human volunteers to examine its effects. An investigational product may be an experimental drug, medical device, or biologic, such as a vaccine, blood product, or gene therapy.
"If the course of illness were always predictable, you would simply observe the treated participants, see how they fared after treatment, and decide whether the treatment helped and what its bad effects were," says Temple.
But most diseases have a variable course, so to find out the effect of a medical product, you must compare a group that got the experimental product (test group) with a group as similar as possible to the test group, but that received an inactive substance (placebo) or a treatment known to be effective. This group is called the control group, thereby making the clinical trial "controlled." Any differences in results between the test group and the control group can then be attributed to the experimental product.
A shortcoming of many early clinical trials was failure to decrease the possibility of bias. Bias refers to any factor that distorts the true outcome of a study, leading to overestimating or underestimating the effect of the product under investigation.
Bias may be introduced when investigators interpret results in one group more favorably than results in the other group, even if they are the same. Or bias may occur when investigators use their knowledge of a participant's condition to assign that person to a specific group; for example, people who are less ill may be assigned to the investigational treatment group.
Randomization to treatment groups and double-blinding are two ways used to minimize bias in clinical trials. Randomization, essentially a coin toss by a computer, means participants are assigned by chance to a group so that neither group will be healthier or more likely to improve than the other.
Blinding is used in conjunction with randomization. Single-blinding means the participant doesn't know whether he or she is receiving the experimental product, an established treatment for that disease, or a placebo--but the research team does know what the participant is receiving. Clinical trials are usually double-blinded, meaning that neither the participant nor the research team knows during the trial which participants receive the experimental product.
Blinding is done to make sure that such factors as investigators' preferences or expectations, or participants' desire to please investigators or hopes of improvement, cannot influence and distort results.
When a company wants to market a drug, it must submit an application to the FDA that includes data from controlled clinical trials. FDA experts review the application to decide whether the clinical trials are well-controlled, whether they show the effectiveness of the product, and whether all available data show that the product is safe enough to allow it on the market.
Proof of Safety
Before 1938, manufacturers could market a drug without submitting any information to the...
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