Types and associated methodologies of overviews of reviews in health care: a methodological study with published examples

Abstract

Objectives: To provide a descriptive insight into the different types of research questions/objectives and associated methodologies of overviews of reviews, supplemented by representative examples from the health care literature.

Study design and setting: We searched in methodological articles for information on types and methodologies used in overviews and we explored the typology of reviews to identify similar types in literature of overviews. We categorized the types of overviews based on the research question/objective and the methodological approach used. Indicative examples for each category were selected from a sample of 2,121 overviews that were retrieved between 2000 and 2022 from MEDLINE, Scopus, and Cochrane Database of Systematic Reviews.

Results: Based on type of research question, overviews were classified as overviews of reviews of interventions, associations, prediction, diagnostic accuracy, prevalence/incidence, experiences/views, economic evaluation, and measurement properties. Based on the methodological approach, we identified a variety of methods (systematic, living, rapid, scoping, evidence mapping, framework, and methodological) used in overviews.

Conclusion: The proposed classification and examples provide an essential starting point for future theory-building research on typologies and study designs of overviews of reviews. It is important for methodologists to make vigorous effort to create consensus-based methodological and reporting guidelines to cover these diverse types and key methodological challenges.

Keywords: Evidence synthesis; Healthcare; Methodology; Overview of reviews; Taxonomy; Typology.