A clinical trial in medicine (synonyms: clinical studies, research protocols, medical research) is a research study that seeks to answer a relevant question in medicine.
The most commonly performed clinical trials evaluate new drugs or medical therapies to patients in strictly scientifically controlled settings. The purpose of such trials is to determine whether one or more treatment options are safe, effective, and better than current standard care. They are designed to be ethical, they must involve the full and informed consent of participating human subjects and they are closely supervised by the appropriate authorities.
The most statistically significant and therefore the trial that gives the best form of medical evidence is the randomized controlled trial. Other forms of clinical trials such as the cohort study and the case-controlled trial are still useful but provide less compelling evidence than the randomized controlled trial.
Currently most drug trials are designed to be randomized, double-blind, and placebo-controlled. This means that each study subject is randomly assigned to receive one of the treatments, which might be the placebo. Neither the subjects nor scientists involved in the study know which study treatment is being administered to any given subject; and, in particular, none of those involved in the study know which subjects are being administered a placebo.
Most clinical trials require large numbers of participants and sometimes it is necessary to organize multicenter clinical trials. Often the centres taking part in such trials are in different countries (in which case they are termed international clinical trials).
