Clinical Trials
The chapter gives an overview of clinical trials. Medical practice has entered an era of "evidence-based medicine" characterized by an increasingly widespread societal belief that clinical practice should be based on scientific information in addition to intuition, mechanistic reasoning, and opinion. The primary tool used to generate definitive medical evidence is the randomized clinical trial (RCT), the essential basis of which is the allocation of a research subject to one intervention or another through a deliberate scheme that uses a table of random numbers to determine the assignment of the intervention. This process ensures that underlying risks are randomly distributed between or among the arms of a study, thus enabling an internally valid comparison of the outcome of interest. There has lately been a growing level of interest in assessing the quality of clinical trials, not only with regard to internal validity, but also in terms of a host of parameters that might guide the application of trial results to informing decisions about the development of medical products, medical practice, or health policy. While the critical importance of clinical trials is widely acknowledged, as a scientific tool, they remain a work in progress. When designing or interpreting the results of a clinical study, the purpose of the investigation is critical to placing the outcome in the appropriate context. Researchers and clinicians who design the investigation are responsible for constructing the project and presenting its results in a manner that reflects the intent of the study. The structural characteristics of trials can be characterized as a function of the attributes such as pragmatic versus explanatory, entry criteria, data collection instrument, etc.
