Trials shed little light on complex interventions
There are challenges in evaluating complex interventions, which contain several interacting components and target one or more behaviours, target more than one group or organisational level, result in different numbers and types of outcome and permit degrees of tailoring or flexibility [It has been suggested that whilst randomised trials may be appropriate for clinical interventions, ‘service innovations are even more complex, and this complexity needs to be embraced, not eliminated’ [Some complex interventions are not ready for trial evaluation. The UK Medical Research Council framework for the development and evaluation of complex interventions recommends the use of multiple research methods, with scope for embedding trials within a broader programme of studies which can also contribute to understanding mechanisms of change [