Methods for improving clinical trials.

Over the past decades, the randomized controlled trial has entered an era of continuous improvement and has gradually become accepted as the most effective way of determining the relative efficacy and toxicity of new therapies because it controls for placebo and time effects. However, even sensitive and properly designed and executed trials do not always confirm hypotheses to be tested, and conclusions are not always confirmed by subsequent trials. Although the former may be due to wrong hypotheses, the latter is likely to be due to the presence of certain imperfections within the design and execution of the trial itself. In this opinion paper, while focusing on such imperfections, the author searched for methods for further improvement of controlled trials, particularly clinical trials. The examples used in this paper are obtained from literature search as well as recent studies performed by the Netherlands Working Group on Cardiovascular Research (WCN). Methods for improvement could include: 1. making every effort to avoid asymmetries in the treatment groups; 2. emphasis on statistical power rather than just null-hypothesis testing; 3. adjusting for asymmetries not only of patient characteristics but also of outcome variables; 4. accounting routinely for type III errors; 5. routinely weighing benefits of a new drug against risks.