Key concepts of clinical trials: a narrative review

Postgrad Med. 2011 Sep;123(5):194-204. doi: 10.3810/pgm.2011.09.2475.


The recent focus of federal funding on comparative effectiveness research underscores the importance of clinical trials in the practice of evidence-based medicine and health care reform. The impact of clinical trials not only extends to the individual patient by establishing a broader selection of effective therapies, but also to society as a whole by enhancing the value of health care provided. However, clinical trials also have the potential to pose unknown risks to their participants, and biased knowledge extracted from flawed clinical trials may lead to the inadvertent harm of patients. Although conducting a well-designed clinical trial may appear straightforward, it is founded on rigorous methodology and oversight governed by key ethical principles. In this review, we provide an overview of the ethical foundations of trial design, trial oversight, and the process of obtaining approval of a therapeutic, from its pre-clinical phase to post-marketing surveillance. This narrative review is based on a course in clinical trials developed by one of the authors (DJM), and is supplemented by a PubMed search predating January 2011 using the keywords "randomized controlled trial," "patient/clinical research," "ethics," "phase IV," "data and safety monitoring board," and "surrogate endpoint." With an understanding of the key principles in designing and implementing clinical trials, health care providers can partner with the pharmaceutical industry and regulatory bodies to effectively compare medical therapies and thereby meet one of the essential goals of health care reform.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Clinical Trials, Phase I as Topic
  • Clinical Trials, Phase II as Topic
  • Clinical Trials, Phase III as Topic
  • Clinical Trials, Phase IV as Topic
  • Drug Evaluation / methods
  • Humans
  • Randomized Controlled Trials as Topic* / ethics
  • Randomized Controlled Trials as Topic* / methods
  • Randomized Controlled Trials as Topic* / standards
  • United States