title: Optimisation of complex health interventions prior to a randomised controlled trial: a scoping review of strategies used.
abstract: BACKGROUND
  Many complex intervention trials fail to show an intervention effect. Although this may be due to genuine ineffectiveness, it may also be the result of sub-optimal intervention design, implementation failure or a combination of these. Given current financial constraints and the pressure to reduce waste and increase value in health services research, pre-trial strategies are needed to reduce the likelihood of design or implementation failure and to maximise the intervention's potential for effectiveness. In this scoping review, we aimed to identify and synthesise the available evidence relating to the strategies and methods used to 'optimise' complex interventions at the pre-trial stage.
  
  
  METHODS
  We searched MEDLINE, CINAHL, AMED, PsycINFO and ProQuest Nursing & Allied Health Source for papers published between January 2000 and March 2015. We included intervention development and optimisation studies that explored potential intervention weaknesses and limitations before moving to a definitive randomised controlled trial (RCT). Two reviewers independently applied selection criteria and systematically extracted information relating to the following: study characteristics; intervention under development; framework used to guide the development process; areas of focus of the optimisation process, methods used and outcomes of the optimisation process. Data were tabulated and summarised in a narrative format.
  
  
  RESULTS
  We screened 3968 titles and 231 abstracts for eligibility. Eighty-nine full-text papers were retrieved; 27 studies met our selection criteria. Optimisation strategies were used for a range of reasons: to explore the feasibility and acceptability of the intervention to patients and healthcare professionals; to estimate the effectiveness and cost-effectiveness of different combinations of intervention components; and to identify potential barriers to implementation. Methods varied widely across studies, from interviews and focus groups to economic modelling and probability analysis.
  
  
  CONCLUSIONS
  The review identifies a range of optimisation strategies currently used. Although a preliminary classification of these strategies can be proposed, a series of questions remain as to which methods to use for different interventions and how to determine when the intervention is ready or 'optimised enough' to be tested in a RCT. Future research should explore potential answers to the questions raised, to guide researchers in the development and evaluation of more effective interventions.
authors.affiliation: NMAHP Research Unit, Glasgow Caledonian University, Level 6, Govan Mbeki Building 70 Cowcaddens Road, Glasgow, G4 0BA Scotland.
authors.forename: Sara
authors.initials: S
authors.lastname: Levati
authors.affiliation: NMAHP Research Unit, Glasgow Caledonian University, Level 6, Govan Mbeki Building 70 Cowcaddens Road, Glasgow, G4 0BA Scotland.
authors.forename: Pauline
authors.initials: P
authors.lastname: Campbell
authors.affiliation: NMAHP Research Unit, Glasgow Caledonian University, Level 6, Govan Mbeki Building 70 Cowcaddens Road, Glasgow, G4 0BA Scotland.
authors.forename: Rachael
authors.initials: R
authors.lastname: Frost
authors.affiliation: NMAHP Research Unit, University of Stirling, Unit 13 Scion House, Innovation Park, Stirling, FK9 4NF UK.
authors.forename: Nadine
authors.initials: N
authors.lastname: Dougall
authors.affiliation: NMAHP Research Unit, University of Stirling, Unit 13 Scion House, Innovation Park, Stirling, FK9 4NF UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Wells
authors.affiliation: Yunus Centre for Social Business and Health, Glasgow Caledonian University, M201, George Moore Building 70 Cowcaddens Road, Glasgow, G4 0BA Scotland.
authors.forename: Cam
authors.initials: C
authors.lastname: Donaldson
authors.affiliation: NMAHP Research Unit, Glasgow Caledonian University, Level 6, Govan Mbeki Building 70 Cowcaddens Road, Glasgow, G4 0BA Scotland.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hagen
keywords: Acceptability; Complex interventions; Effectiveness; Intervention development; Modelling; Optimisation; Pre-trial; Scoping review