Clinical Trials

Clinical trials are experimental studies performed mainly on humans, but sometimes on animals, tissues, and cultures as well, to assess the effectiveness and safety of an intervention under investigation such as a new drug, diagnostic procedure, surgical procedure, prophylactic procedure, or screening program. There are many types of clinical trials. This entry focuses on randomized controlled clinical trials and randomized crossover designs for studying treatment effects. Rigorously designed clinical trials such as randomized concurrently controlled clinical trials conducted with human subjects, usually patients, have become well established as the scientific method based on empirical evidence that investigators must use to assess new treatments if their claims are to find widespread acceptance. Clinical trials have become indispensable in discovering new techniques to prevent and treat diseases, ...