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Research Methods & Reporting

A new framework for developing and evaluating complex interventions: update of Medical Research Council guidance

BMJ 2021; 374 doi: (Published 30 September 2021) Cite this as: BMJ 2021;374:n2061
  1. Kathryn Skivington, research fellow1,
  2. Lynsay Matthews, research fellow1,
  3. Sharon Anne Simpson, professor of behavioural sciences and health1,
  4. Peter Craig, professor of public health evaluation1,
  5. Janis Baird, professor of public health and epidemiology2,
  6. Jane M Blazeby, professor of surgery3,
  7. Kathleen Anne Boyd, reader in health economics4,
  8. Neil Craig, acting head of evaluation within Public Health Scotland5,
  9. David P French, professor of health psychology6,
  10. Emma McIntosh, professor of health economics4,
  11. Mark Petticrew, professor of public health evaluation7,
  12. Jo Rycroft-Malone, faculty dean8,
  13. Martin White, professor of population health research9,
  14. Laurence Moore, unit director1
  1. 1MRC/CSO Social and Public Health Sciences Unit, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
  2. 2Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
  3. 3Medical Research Council ConDuCT-II Hub for Trials Methodology Research and Bristol Biomedical Research Centre, Bristol, UK
  4. 4Health Economics and Health Technology Assessment Unit, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
  5. 5Public Health Scotland, Glasgow, UK
  6. 6Manchester Centre for Health Psychology, University of Manchester, Manchester, UK
  7. 7London School of Hygiene and Tropical Medicine, London, UK
  8. 8Faculty of Health and Medicine, Lancaster University, Lancaster, UK
  9. 9Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK
  1. Correspondence to: K Skivington Kathryn.skivington{at}
  • Accepted 9 August 2021

The UK Medical Research Council’s widely used guidance for developing and evaluating complex interventions has been replaced by a new framework, commissioned jointly by the Medical Research Council and the National Institute for Health Research, which takes account of recent developments in theory and methods and the need to maximise the efficiency, use, and impact of research.

Complex interventions are commonly used in the health and social care services, public health practice, and other areas of social and economic policy that have consequences for health. Such interventions are delivered and evaluated at different levels, from individual to societal levels. Examples include a new surgical procedure, the redesign of a healthcare programme, and a change in welfare policy. The UK Medical Research Council (MRC) published a framework for researchers and research funders on developing and evaluating complex interventions in 2000 and revised guidance in 2006.123 Although these documents continue to be widely used and are now accompanied by a range of more detailed guidance on specific aspects of the research process,45678 several important conceptual, methodological and theoretical developments have taken place since 2006. These developments have been included in a new framework commissioned by the National Institute of Health Research (NIHR) and the MRC.9 The framework aims to help researchers work with other stakeholders to identify the key questions about complex interventions, and to design and conduct research with a diversity of perspectives and appropriate choice of methods.

Summary points

  • Complex intervention research can take an efficacy, effectiveness, theory based, and/or systems perspective, the choice of which is based on what is known already and what further evidence would add most to knowledge

  • Complex intervention research goes beyond asking whether an intervention works in the sense of achieving its intended outcome—to asking a broader …

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