Designing clinical trials

Abstract

A clinical trial is the gold standard study design to assess the effectiveness of interventions in health care. Yet, often paradoxically, clinicians find that the benefits of the randomized controlled clinical trial cannot be replicated in an actual clinical practice. A tradeoff between practicality and ideal trial requirements is needed to develop a pragmatic clinical trial. The results of a pragmatically constituted trial are more likely to be acceptable to practicing clinicians. The major steps and requirements and practices for a clinical trial by clinicians are summarized in this article. The PICOT format is a helpful approach to summarize research questions that explore the effects of therapy. Next, depending on the feasibility, the study population is selected by using inclusion and exclusion criteria. The needed sample size is calculated from this representative study population by providing clinical data inputs to a statistician. It is essential that chance, all possible forms of bias and confounding factors are eliminated or balanced between the study groups. This is ensured by randomization, proper allocation concealment, and masking. A clinical trial also needs to pass through relevant review boards and should be ethical. The good clinical practice guidelines throw light on this aspect. Finally, it is very important that a clinical trial is reported adequately such that readers understand the trial's design, conduct, analysis and interpretation, and can assess the validity of its results. The CONSORT guidelines are very useful in this regard.