Clinical trials in sudden cardiac death prevention: Principles and endpoints
Research questions can be approached by means of observational studies, case-control studies, or randomized controlled trials (RCTs). Observational studies are often useful for developing research ideas, but are vulnerable to bias due to an uncontrolled process of treatment assignment. Occasionally, case-control studies may be the only feasible option open to researchers, but such studies are also potentially subject to bias. Randomized controlled trials are currently recognized as the best tool available for definitive comparison of proposed medical therapies, and are pivotal in the practice of evidence based medicine.1-3 They involve prospective follow-up of patients and compare two or more treatment assignments, one of which is often placebo or a standard treatment. Patients enrolled in an RCT should reflect a welldefined population, selected on the basis of study inclusion and exclusion criteria and enrolled consecutively to avoid the possibility of conscious or unconscious selectiveness in including or excluding patients. The essential feature of RCTs is that they are designed so that treatments are assigned entirely at random, rather than as a result of standard medical care, as would be the case in a prospective observational study. © 2008 Springer-Verlag London Limited.
