Realist randomised controlled trials: A new approach to evaluating complex public health interventions

► 'Realists' argue that RCTs ignore the complexity of causation and fail to ask which interventions work, for whom and when. ► We disagree but believe RCTs should examine for whom and when interventions work. ► To this end, RCTs could aim to examine intervention mechanisms of change and how intervention effects vary with context. ► “Realist” RCTs should examine the validity of intervention theory to better inform policy and practice in the long term.