How Clinical Trials Work

A clinical trial is a research study designed to answer specific questions about a new treatment or a new way of using current treatments. Clinical trials are used to establish whether new treatments are safe and effective. It is very important to understand that the new treatment may not be better than, or even as good as, existing treatments.

Most drugs and treatments that are widely accepted by the medical community have been tested in clinical trials. If a trial is successful, meaning the treatment is shown to be both safe and effective, the experimental treatment can become standard treatment.

Clinical Trials Are Not All Equal

A clinical trial may be at a different stage—for example, testing safety, dosage, or effectiveness (see below). Also, although the types of patient protections described on this Web site are widely accepted and employed in the design of clinical trials, there may be a wide range in the quality of clinical trials and the scientific evidence supporting them. Discuss any clinical trials you may be considering with a trusted physician.

There Are Four Stages of Testing in Clinical Trials

In phase I trials, a small group of people is tested. The goal of such trials is to determine the safe dosage range and to identify the side effects of a drug or treatment. Therapeutic benefit, while not excluded, is not the primary goal of this initial phase of clinical testing. If a treatment has unacceptable side effects at this stage, further trials are not initiated.
Next are phase II trials. A larger group of patients is treated based on the findings of the phase I trial. Here, investigators test whether a treatment is effective, while they continue to monitor side effects.
In a phase III trial, a larger group of patients is treated to confirm effectiveness compared to standard treatment(s).
Phase IV trials happen after a drug has made it to the market, and serve as a follow-up to examine effectiveness and side-effects on very large patient populations. It can happen that rare but serious side effects are only detected during large phase IV trials.

Control Groups

A typical clinical trial has an experimental treatment group, which consists of patients receiving an experimental treatment, while another group serves as the control group. The results in the experimental treatment group are compared to the control group to determine the effect of the treatment. In most cases the control group receives a standard treatment for the disease. If there is no standard treatment, the group may receive no intervention. Sometimes evidence gathered from historical studies can serve as the control group.

The results of these trials are analyzed using statistics to determine whether any difference between the groups might be due to coincidence or placebo effect. Whenever possible, clinical trials are "double blind". This means that neither the physician nor patient knows who gets the new treatment, and who does not. However, this is not always feasible.

Oversight and Informed Consent

A further characteristic of clinical trials is oversight, both at the local level (the treating hospital or institution) and in many countries at the government level (for example, the European Medicines Agency (EMA) or the U.S. Food and Drug Administration). Oversight at multiple levels promotes the scientific validity of the experimental treatment, and protects the patients. One requirement is appropriate informed consent. This means that the patients are informed about the goal, duration, potential risks and nature of the treatment (See Section 8 of the Patient Handbook). It is important to realize that while participating in a clinical trial may benefit the patient, there is no guarantee that this will be the case, as these trials are undertaken firstly to test whether or not a treatment is safe; and if it is safe whether or not it offers any benefit. Furthermore, unexpected side effects may occur. If these are serious, the trial will be stopped.