There are different types of clinical trials: treatment, prevention, diagnostic, screening, and quality of life trials—and the trials are conducted in progressive phases (I-IV). To ensure that no one can influence the results of a study, clinical trials employ a range of specialized testing mechanisms intended to prevent bias and provide reliable results: [8]
In addition, some clinical trials are called open-label studies, because both the user and the researcher know that the user is receiving the treatment, and not the placebo.
By federal regulation, every clinical trial in the United States must be approved and monitored by an Institutional Review Board (IRB), an independent committee of physicians, statisticians, community advocates, and others. The IRB is charged with ensuring that all clinical trials within a given medical institution are ethical and that the rights of the participants in those trials are protected.
Clinical trials retain very specific participation guidelines. Establishing and maintaining these guidelines is a critical part of producing meaningful and reliable results. The factors that allow someone to participate in a clinical trial are called “inclusion criteria”, while those that disallow someone are called “exclusion criteria”. Typical criteria include age, gender, the type and stage of a disease, previous treatment history, and other medical conditions.