title: A research and development agenda for systematic reviews that ask complex questions about complex interventions.
abstract: OBJECTIVE
  This article outlines a research and development agenda for systematic reviews that ask complex questions about interventions varying in degree and type of complexity.
  
  
  METHODS
  Consensus development by key authors of articles on methodological challenges in systematic reviews of complex interventions, based on a 2-day workshop in Montebello, Canada, January 2012.
  
  
  RESULTS
  There is an urgent need for a more precise and consistently applied lexicon and language to disaggregate several conceptually distinct dimensions of "complexity." Selected current evidence synthesis methods have potential application in reviews where complexity is important. There is a lack of evaluation of methods to better understand the nature of complex interventions and the optimal processes of synthesizing and interpreting evidence from these systematic reviews. Gaps in methods, knowledge, and know-how exist, and there is a need for additional guidance.
  
  
  CONCLUSIONS
  Understanding how complexity can impact on findings of systematic reviews is critical. Experience in applying methods that have been developed to facilitate this understanding is limited, and the degree to which these approaches improve the systematic review process or transparency is only partially understood. Future research should concentrate on the impact of complexity on the systematic review process and findings and on further methodological development.
authors: School of Healthcare Sciences, Bangor University, Bangor, UK LL57 2EF.
authors: Jane
authors: J
authors: Noyes
authors: David
authors: D
authors: Gough
authors: Simon
authors: S
authors: Lewin
authors: Alain
authors: A
authors: Mayhew
authors: Susan
authors: S
authors: Michie
authors: Tomas
authors: T
authors: Pantoja
authors: Mark
authors: M
authors: Petticrew
authors: Kevin
authors: K
authors: Pottie
authors: Eva
authors: E
authors: Rehfuess
authors: Ian
authors: I
authors: Shemilt
authors: Sasha
authors: S
authors: Shepperd
authors: Amanda
authors: A
authors: Sowden
authors: Peter
authors: P
authors: Tugwell
authors: Vivian
authors: V
authors: Welch
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D012107:Research Design; D012196:Review Literature as Topic
keywords: Complex intervention; Complexity; Consensus development; Evaluation; Evidence synthesis methods; Research and development agenda