Know how: How to avoid common mistakes in the design of clinical trials

Research into medicines relies heavily on clinical trials. Here, NIHR Research for Patient Benefit programme director David Armstrong poses five questions you must be sure to answer in your research application.

Randomised controlled clinical trials are now recognised as the gold standard for evaluating the effectiveness of medical interventions. Trials therefore form a significant proportion of the UK National Institute for Health Research’s portfolio and applications for new ones are constantly being assessed across the institute’s various programmes.

As the design of trials is so well developed, much of any research application will be fairly formulaic. For example, randomisation must be conducted by a third party and every trial must have a section describing how and why the sample size has been calculated. These requirements are not negotiable. But there are several aspects of designing a trial that are not prescribed and it is these judgment calls that form the focus of the funding panel’s assessment. Five common areas are described below.