Review of Designs for Accommodating Patients’ or Physicians’ Preferences in Randomized Controlled Trials

The randomized controlled trial (RCT) is regarded as the principal way to collect scientific data on the efficacy of health interventions. Despite the advantages of RCT design in reducing extraneous variation that may confound interpretation of intervention results, the design may not be suitable for interventions in which patients are likely to have a strong preference for a particular treatment. Some designs incorporating patients or physician preferences by allowing at least a subgroup of them to choose their treatment have been proposed. In this chapter, we review various randomized control trials designs for accommodating participants’ and professionals’ preferences. Specifically, we discuss the advantages, limitations, applicability, ethical issues and statistical issues of each design. We also discuss the estimation of treatment effect (a measure of the extent to which treatment difference is attributable to treatments); selection effect (a measure of the extent to which treatment response is influenced by self-selection of treatment by patients); and preference effect (a measure of the extent to which treatment difference is caused by an interaction between the patient’s choice of treatment and the treatment actually received).