The Randomized Clinical Trial: Study Design and Execution

LR SUTHERLAND. The randomized clinical trial: Study design and execution. Can J Gastroenterol 1993;7(7):557-560. The clinical trial has been described as the indispensable ordeal and physicians base many clinical care decisions on information gaineJ from such trials. As well, the methodology of a trial can be used just as effectively to look at various treatment stratagems. The accomplishments of clinical trials include that they have modified practice patterns {eg, the prescribing habits of physicians in the '90s, compared with the '60s, are more often founded on reality as reflected by clinical trials) and have buttressed the concept that disease is quite heterogeneous (as the inclusion and exclusion criteria are defined within a clinical trial, it is possible to begin to appreciate the heterogeneity of the disease). This paper will consist of a brief review of the historical developments of the clinical trial and the various stages of a clinical trial from initiation to completion. Various design features, focusing on selection of the test and control treatments, establishing comparable study groups, and some suggestions about blinding and controlling bias will also be reviewed.