Psychological issues in clinical trial design

Abstract

Randomised control trial (RCT) designs are widely regarded as the trial design of choice, believed to offer greater internal validity than non-random trials. However, where patients have preferences among treatments to be compared, randomisation can create differences between groups in a trial.
The limitations of conventional RCTs are considered in the context of treatments for chronic conditions where patients often have strong treatment preferences. Precautions required in selection and recruitment of patients into RCTs are recommended together with strategies for evaluating any effects of preferences.
Alternative trial designs which take account of patients' and/or doctors' preferences when recruiting preferences and allocating treatments are reviewed, and recommendations made.