Definition of Clinical trials

Clinical trials: Trials to evaluate the effectiveness and safety of medications or medical devices by monitoring their effects on large groups of people.

Clinical research trials may be conducted by government health agencies such as NIH, researchers affiliated with a hospital or university medical program, independent researchers, or private industry.

Usually volunteers are recruited, although in some cases research subjects may be paid. Subjects are generally divided into two or more groups, including a control group that does not receive the experimental treatment, receives a placebo (inactive substance) instead, or receives a tried-and-true therapy for comparison purposes.

Typically, government agencies approve or disapprove new treatments based on clinical trial results. While important and highly effective in preventing obviously harmful treatments from coming to market, clinical research trials are not always perfect in discovering all side effects, particularly effects associated with long-term use and interactions between experimental drugs and other medications.

For some patients, clinical research trials represent an avenue for receiving promising new therapies that would not otherwise be available. Patients with difficult to treat or currently "incurable" diseases, such as AIDS or certain types of cancer, may want to pursue participation in clinical research trials if standard therapies are not effective. Clinical research trials are sometimes lifesaving.

There are four possible outcomes from a clinical trial:

• Positive trial -- The clinical trial shows that the new treatment has a large beneficial effect and is superior to standard treatment.
• Non-inferior trial -- The clinical trial shows that that the new treatment is equivalent to standard treatment. Also called a non-inferiority trial.
• Inconclusive trial -- The clinical trial shows that the new treatment is neither clearly superior nor clearly inferior to standard treatment.
• Negative trial -- The clinical trial shows that a new treatment is inferior to standard treatment.