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Health (Nursing, Medicine, Allied Health)

Guide to research sources and tools for locating health evidence in books, journals, databases.

Types of Evidence Synthesis / Literature Reviews

Literature reviews are are comprehensive summaries and syntheses of the previous research on a given topic.  While narrative reviews are common across all academic disciplines, reviews that focus on appraising and synthesizing research evidence are increasingly important in the health and social sciences.  

Most evidence synthesis methods use formal and explicit methods to identify, select and combine results from multiple studies, making evidence synthesis a form of meta-research.  

The review purpose, methods used and the results produced vary among different kinds of literature reviews; some of the common types of literature review are detailed below.

Common Types of Literature Reviews1

Narrative (Literature) Review

  • A broad term referring to reviews with a wide scope and non-standardized methodology
  • Search strategies, comprehensiveness of literature search, time range covered and method of synthesis will vary and do not follow an established protocol

Integrative Review

  • A type of literature review based on a systematic, structured literature search
  • Often has a broadly defined purpose or review question
  • Seeks to generate or refine and theory or hypothesis and/or develop a holistic understanding of a topic of interest
  • Relies on diverse sources of data (e.g. empirical, theoretical or methodological literature; qualitative or quantitative studies)

Systematic Review

  • Systematically and transparently collects and categorize existing evidence on a question of scientific, policy or management importance
  • Follows a research protocol that is established a priori
  • Compares, evaluates, and synthesizes evidence in a search for the effect of an intervention
  • Time-intensive and often takes months to a year or more to complete 
  • The most commonly referred to type of evidence synthesis; sometimes confused as a blanket term for other types of reviews

Meta-Analysis

  • Statistical technique for combining the findings from disparate quantitative studies
  • Uses statistical methods to objectively evaluate, synthesize, and summarize results
  • Often conducted as part of a systematic review

Scoping Review

  • Systematically and transparently collects and categorizes existing evidence on a broad question of scientific, policy or management importance
  • Seeks to identify research gaps, identify key concepts and characteristics of the literature and/or examine how research is conducted on a topic of interest
  • Follows a research protocol that is established a priori
  • Useful when the complexity or heterogeneity of the body of literature does not lend itself to a precise systematic review
  • Useful if authors do not have a single, precise review question
  • May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would 
  • May take longer than a systematic review

Rapid Review

  • Applies a systematic review methodology within a time-constrained setting
  • Follows a research protocol that is established a priori
  • Employs methodological "shortcuts" (e.g., limiting search terms and the scope of the literature search), at the risk of introducing bias
  • Useful for addressing issues requiring quick decisions, such as developing policy recommendations

Umbrella Review

  • Reviews other systematic reviews on a topic
  • Often defines a broader question than is typical of a traditional systematic review
  • Most useful when there are competing interventions to consider
  • Follows a research protocol that is established a priori

1. Adapted from:

Eldermire, E. (2021, November 15). A guide to evidence synthesis: Types of evidence synthesis. Cornell University LibGuides. https://guides.library.cornell.edu/evidence-synthesis/types

Nolfi, D. (2021, October 6). Integrative Review: Systematic vs. Scoping vs. Integrative. Duquesne University LibGuides. https://guides.library.duq.edu/c.php?g=1055475&p=7725920

Delaney, L. (2021, November 24). Systematic reviews: Other review types. UniSA LibGuides. https://guides.library.unisa.edu.au/SystematicReviews/OtherReviewTypes

 

Choosing a Review Type

For guidance related to choosing a review type, see:

Further Reading: Exploring Different Types of Literature Reviews

Integrative Reviews

"The integrative review method is an approach that allows for the inclusion of diverse methodologies (i.e. experimental and non-experimental research)." (Whittemore & Knafl, 2005, p. 547).

Scoping Reviews

Scoping reviews are evidence syntheses that are conducted systematically, but begin with a broader scope of question than traditional systematic reviews, allowing the research to 'map' the relevant literature on a given topic.

Rapid Reviews

Rapid reviews are systematic reviews that are undertaken under a tighter timeframe than traditional systematic reviews.