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Qualitative evidence synthesis for complex interventions and guideline development: clarification of the purpose, designs and relevant methods
  1. Kate Flemming1,
  2. Andrew Booth2,
  3. Ruth Garside3,
  4. Özge Tunçalp4,
  5. Jane Noyes5
  1. 1Department of Health Sciences, Faculty of Science, The University of York, York, UK
  2. 2School of Health and Related Research, University of Sheffield, Sheffield, UK
  3. 3European Centre for Environment and Human Health, University of Exeter, Truro, UK
  4. 4Department of Reproductive Health and Research including UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), World Health Organization, Geneva, Switzerland
  5. 5School of Social Sciences, Bangor University, Bangor, UK
  1. Correspondence to Dr Kate Flemming; kate.flemming{at}


This paper is one of a series exploring the implications of complexity for systematic reviews and guideline development, commissioned by the WHO. The paper specifically explores the role of qualitative evidence synthesis. Qualitative evidence synthesis is the broad term for the group of methods used to undertake systematic reviews of qualitative research evidence. As an approach, qualitative evidence synthesis is increasingly recognised as having a key role to play in addressing questions relating to intervention or system complexity, and guideline development processes. This is due to the unique role qualitative research can play in establishing the relative importance of outcomes, the acceptability, fidelity and reach of interventions, their feasibility in different settings and potential consequences on equity across populations. This paper outlines the purpose of qualitative evidence synthesis, provides detail of how qualitative evidence syntheses can help establish understanding and explanation of the complexity that can occur in relation to both interventions and systems, and how qualitative evidence syntheses can contribute to evidence to decision frameworks. It provides guidance for the choice of qualitative evidence synthesis methods in the context of guideline development for complex interventions, giving ‘real life’ examples of where this has occurred. Information to support decision-making around choice qualitative evidence synthesis methods in the context of guideline development is provided. Approaches for reporting qualitative evidence syntheses are discussed alongside mechanisms for assessing confidence in the findings of a review.

  • health services research
  • systematic review
  • qualitative study

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  • Handling editor Soumyadeep Bhaumik

  • Contributors KF drafted the article. AB, RG, JN and ÖT contributed to sections of the final draft article and all authors provided comments on final drafts prior to completion and submission. All read comments from reviewers and contributed to the amended version. For final draft, KF made changes and coauthors read and agreed to changes.

  • Funding Funding provided by the World Health Organization Department of Maternal, Newborn, Child and Adolescent Health through grants received from the United States Agency for International Development and the Norwegian Agency for Development Cooperation.

  • Disclaimer ÖT is a staff member of WHO. The author alone is responsible for the views expressed in this publication and they do not necessarily represent the decisions or policies of WHO.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data are available.

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