title: Realist complex intervention science: Applying realist principles across all phases of the Medical Research Council framework for developing and evaluating complex interventions.
abstract: The integration of realist evaluation principles within randomised controlled trials ('realist RCTs') enables evaluations of complex interventions to answer questions aboutwhat works, for whom and under what circumstances. This allows evaluators to better develop and refine mid-level programme theories. However, this is only one phase in the process of developing and evaluating complex interventions. We describe and exemplify how social scientists can integrate realist principles acrossall phasesof the Medical Research Council framework. Intervention development, modelling, and feasibility and pilot studies need to theorise the contextual conditions necessary for intervention mechanisms to be activated. Where interventions are scaled up and translated into routine practice, realist principles also have much to offer in facilitating knowledge about longer-term sustainability, benefits and harms. Integrating a realist approach across all phases of complex intervention science is vital for considering the feasibility and likely effects of interventions for different localities and population subgroups.
authors.affiliation: Cardiff University, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Fletcher
authors.affiliation: UCL Institute of Education, UK.
authors.forename: Farah
authors.initials: F
authors.lastname: Jamal
authors.affiliation: Cardiff University, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Moore
authors.affiliation: Cardiff University, UK.
authors.forename: Rhiannon E
authors.initials: RE
authors.lastname: Evans
authors.affiliation: Cardiff University, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Murphy
authors.affiliation: London School of Hygiene & Tropical Medicine, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Bonell
keywords: Complex interventions; complex systems; evaluation; pilot trials; public health; randomised controlled trials; realism