Clinical Trials

DEFINITION of 'Clinical Trials'

The study of human volunteers for the purpose of evaluating the safety and efficacy of a medical treatment. Clinical trials evaluate drugs, devices, procedures or behavior modifications to see if they are helpful or harmful and if they are more effective, less effective or equally as effective as existing treatments or when compared with a placebo.

BREAKING DOWN 'Clinical Trials'

Drugs usually undergo three phases of clinical trials. The first phase tests a drug’s delivery, dosage and safety on a small group of people. The second phase uses a larger test group. Most drugs fail in one of these phases, but if they reach phase 3, they are tested on an even larger group and compared with a placebo or with the currently accepted treatment. Only about 5% of drugs pass all three phases of clinical trials and get approved for sale.

There are several types of clinical trials. A single arm trial has no comparison group. A randomized, controlled trial has two groups of patients that are randomly assigned to receive either the test treatment or the placebo. If the trial is double blind, neither the patients nor the doctors know which group is which until the study is over. This type of study helps eliminate bias. The knowledge gained from a clinical study can help to treat, diagnose or prevent medical problems.

Statistical analysis is a key component of evaluating the results of a clinical trial: Did the treatment really have an effect, or were the results as likely as a chance outcome? Despite extensive testing, it can be difficult to tell whether a drug that appears to be effective really is. In addition, while clinical trials might show that a drug does or doesn’t work, they don’t necessarily tell us why. Another shortcoming of clinical trials is that the test subjects are often healthier than the patients who would actually use the treatment being tested.