Framework for the development and evaluation of complex interventions: gap analysis, workshop and consultation-informed update

Health Technol Assess. 2021 Sep;25(57):1-132. doi: 10.3310/hta25570.


Background: The Medical Research Council published the second edition of its framework in 2006 on developing and evaluating complex interventions. Since then, there have been considerable developments in the field of complex intervention research. The objective of this project was to update the framework in the light of these developments. The framework aims to help research teams prioritise research questions and design, and conduct research with an appropriate choice of methods, rather than to provide detailed guidance on the use of specific methods.

Methods: There were four stages to the update: (1) gap analysis to identify developments in the methods and practice since the previous framework was published; (2) an expert workshop of 36 participants to discuss the topics identified in the gap analysis; (3) an open consultation process to seek comments on a first draft of the new framework; and (4) findings from the previous stages were used to redraft the framework, and final expert review was obtained. The process was overseen by a Scientific Advisory Group representing the range of relevant National Institute for Health Research and Medical Research Council research investments.

Results: Key changes to the previous framework include (1) an updated definition of complex interventions, highlighting the dynamic relationship between the intervention and its context; (2) an emphasis on the use of diverse research perspectives: efficacy, effectiveness, theory-based and systems perspectives; (3) a focus on the usefulness of evidence as the basis for determining research perspective and questions; (4) an increased focus on interventions developed outside research teams, for example changes in policy or health services delivery; and (5) the identification of six 'core elements' that should guide all phases of complex intervention research: consider context; develop, refine and test programme theory; engage stakeholders; identify key uncertainties; refine the intervention; and economic considerations. We divide the research process into four phases: development, feasibility, evaluation and implementation. For each phase we provide a concise summary of recent developments, key points to address and signposts to further reading. We also present case studies to illustrate the points being made throughout.

Limitations: The framework aims to help research teams prioritise research questions and design and conduct research with an appropriate choice of methods, rather than to provide detailed guidance on the use of specific methods. In many of the areas of innovation that we highlight, such as the use of systems approaches, there are still only a few practical examples. We refer to more specific and detailed guidance where available and note where promising approaches require further development.

Conclusions: This new framework incorporates developments in complex intervention research published since the previous edition was written in 2006. As well as taking account of established practice and recent refinements, we draw attention to new approaches and place greater emphasis on economic considerations in complex intervention research. We have introduced a new emphasis on the importance of context and the value of understanding interventions as 'events in systems' that produce effects through interactions with features of the contexts in which they are implemented. The framework adopts a pluralist approach, encouraging researchers and research funders to adopt diverse research perspectives and to select research questions and methods pragmatically, with the aim of providing evidence that is useful to decision-makers.

Future work: We call for further work to develop relevant methods and provide examples in practice. The use of this framework should be monitored and the move should be made to a more fluid resource in the future, for example a web-based format that can be frequently updated to incorporate new material and links to emerging resources.

Funding: This project was jointly funded by the Medical Research Council (MRC) and the National Institute for Health Research (Department of Health and Social Care 73514).


Plain language summary

Interventions are actions taken to make a change, for example heart surgery, an exercise programme or a smoking ban in public. Interventions are described as complex if they comprise several stages or parts or if the context in which they are delivered is complex. A framework on how to develop and evaluate complex interventions was last published by the Medical Research Council in 2006 (Craig P, Dieppe P, Macintyre S, Michie S, Nazareth I, Petticrew M. Developing and Evaluating Complex Interventions. London: Medical Research Council; 2006). This document describes how the framework has been updated to include advances in research methods and thinking and presents the new framework document. The updating process had four stages: (1) review of the literature to identify areas requiring update; (2) workshop of experts to discuss topics to update; (3) open consultation on a draft of the framework; and (4) writing the framework. The updated framework divides the research process into four phases: development, feasibility, evaluation and implementation. Key updates include: the definition of a complex intervention was changed to include both the content of the intervention and the context in which it is conductedaddition of systems thinking methods: an approach that considers the broader system an intervention sits withinmore emphasis on interventions that are not developed by researchers (e.g. policy changes and health services delivery)emphasis on the usefulness of evidence as the key goal of complex intervention researchidentification of six elements to be addressed throughout the research process: context; theory refinement and testing; stakeholder involvement; identification of key uncertainties; intervention refinement; and economic considerations. The updated framework is intended to help those involved in funding and designing research to consider a range of approaches, questions and methods and to choose the most appropriate. It also aims to help researchers conduct and report research that is as useful as possible to users of research.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Forecasting
  • Humans
  • Referral and Consultation*