Rethinking pragmatic randomised controlled trials: introducing the "cohort multiple randomised controlled trial" design

The cmRCT design appears to be a workable and useful approach to pragmatic research questions that aim to inform healthcare decisions within routine practice. The design is best suited to circumstances that require open (rather than blinded) trials where "treatment as usual" is compared with the offer of study treatment, and to questions with outcomes that can be easily measured in the whole cohort (for example, patient reported outcomes). Clinical conditions where many clinical trials will be conducted and trials of desirable or expensive interventions are also well suited to the cmRCT approach. There are challenges to the cmRCT design. Further research is required to address a range of analysis and implementation questions related to the design and the ethics of patient centred informed consent for pragmatic randomised controlled trials. In his Harveian oration at the Royal College of Physicians, London, Professor Michael Rawlins, chair of the National Institute for Health and Clinical Excellence, called for "investigators to continue to develop and improve their methodologies in order to help decision makers appraise the evidence."22 We hope that the cmRCT design goes some way towards addressing the problems associated with existing approaches. If these problems are addressed, then perhaps the most important problem of all will be resolved-the non-implementation of the results of clinical research.