sClinical Trials: Basic Information

Clinical Trials:  Basic Information

A variety of types of clinical trials are conducted and including treatment, prevention, and comparative effectiveness type studies.  Clinical trials also must pass through 3-4 sequential phases of study design before being considered for approval by the FDA. 

Types of Clinical Trials:

Treatment Studies:

Are studies in which drugs are compared for effectiveness and side-effects.


Device studies look for effectiveness of a device.  The new device may be compared to an already approved device, or the device may be an all together new concept.  Examples of devices that have gone through clinical research studies include: pacemakers, cardiac stents,


Prevention studies test new inventions designed to prevent the occurrence of cancer in high-risk individuals.


 Registry studies follow the progress of patients whose treatment has been approved by the FDA already.  Registry studies may be a comparative effectiveness trial (comparing two or more already approved treatments), or a Phase IV study, where data is continued to be collected on a treatment that has recently been approved by the FDA. 
Comparative Effectiveness  Comparative effectiveness studies compare two or more comparable treatments for a condition that were previously approved for use but no real data exists as to which is the better, more cost effective treatment.  Currently, in the U.S. these kinds of studies are much needed since many treatment options exist for a given treatment but the treatments were never previously compared in a clinical trial setting. 

Correlative Studies

 Correlative studies are sub-group in which a smaller, but related study exists within a main study.  An example of this may be a blood draw correlative study where a patient's blood is checked for the dose of drug circulating in the body.  Sometimes these studies are optional and require a separate consent. 

Phases of Clinical Trials:

Clinical trials evaluate new therapies in four sequential phases to determine their usefulness in future clinical practice.  Each study phase must prove that the drug is safe and at least as effective as standard therapy alone. 


Phase I:

In the first phase, humans are given new drugs for the first time.  The new drug is tested to est ablish safety, maximum tolerated dose, and the optimal schedule of administration

Phase II.

Once safety has been established in a phase I trial, phase II trials move forward to evaluate the effectiveness of treatment in the cancer being studied.  Side effects and optimal dosing schedules are further identified from the phase I study.

Phase III:

The goal of phase III studies is to build on knowledge gained during phase I and II studies and compare the new treatment to standard established treatments.  Phase III studies involve many more panties; often take years to complete but will ultimatleyh help to improve and redefine the standard of care.

Phase IV:

These studies seek to expand the current usage of an approved drug to evaluate other indications that might prove beneficial and to expand our appreciation of side effects. 

Pilot Study

Pilot studies take an initial look at a clinical trial idea and collect basic information to help design a future trial.  Collecting "background information" is used to validate an idea for a clinical trial. 









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