Multi-arm trials that use a parallel-group design and have three or more groups offer the opportunity to address more than one research question. They can speed up the evaluation of new interventions and facilitate head-to-head comparisons with competing treatment options. These trials appeal to clinicians and patients because they also increase the likelihood of receiving an experimental intervention rather than standard care.
Multi-arm parallel-group randomised clinical trials typically include multiple interventions, combinations of interventions, different doses of an intervention, a placebo and no intervention or treatment as usual. These elements can be combined in various ways resulting in numerous possible trial structures.
Read more (Nuffield Department of Population Health website)