Refresher Definitions

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Evidence Synthesis

An Evidence synthesis is broadly defined as the rigorous and systematic: (1) Collection; (2) Evaluation; (3) Analysis and (4) Synthesis of  research studies and related literature.

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Systematic Review

Systematic reviews are defined as:

An attempt to collect, appraise and synthesize all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research or clinical question. (Cochrane Handbook for Systematic Reviews of Intervention)

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Scoping Reviews, Mapping Reviews and Evidence or Gap Maps (EGM)

 

Scoping Reviews, Mapping Reviews and Evidence or Gap Maps (EGM) are very similar in nature. They are part of the same Evidence Synthesis family. Scoping Reviews, Mapping Reviews and EGM use a broad exploratory research question / topic.

These three evidence synthesis research types can be considered complimentary, sometimes containing elements of multiple types of these reviews. Definitions and reporting guidelines are still being developed for these. In fact, the terminology for each of these evidence synthesis is sometimes used interchangeably. Scoping Reviews have been called scoping studies, systematic scoping reviews, mapping reviews, and mapping studies.

The research methodology and reporting of outcomes differentiates these evidence synthesis types. Mapping reviews and Evidence or Gap Maps differ from Scoping Reviews in that they incorporate quantitative bibliographic analyses.

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Scoping Review

Scoping reviews are defined as:

An initial exploratory synthesis on a new research topic, not yet examined, or broad or multi-question research topic area.

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Mapping Review

Mapping reviews are defined as:

The main distinction [is] the involvement of stakeholders early and the review process,  the rigor of the search strategy and the presentation of results that may be in  user-friendly format, often a visual figure or graph, or a searchable database (Miake-Lye et al, 2016).

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Evidence or Gap Map

Evidence or Gap Maps may accompany a Mapping Review. Evidence or Gap maps are defined as:

A systematic visual presentation of all relevant evidence of a specified kind for a particular topic, sub-topic, or geography. Evidence or Gap Maps are made of a primary table / chart with rows and columns. Evidence or Gap Maps use filters to explore specific variables within the map (e.g., population, or study designs). It is a visual, web-based, and interactive output. (Campbell et al, 2023).

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Comparison chart of Systematic Reviews, Mapping Reviews, and Scoping Reviews

Parameter	Systematic Review	Mapping Review	Scoping Review
Objective	What is the best evidence for clinical intervention decision-making?	Where is the evidence?	What is the extent of knowledge in an emerging research area? Or what are the characteristics or concepts in a research area?
Research question format	PICO / (S,T)	P (Population); O (Outcome)	P (Population) C (Concept); C (Context)
Research / clinical question aim	Answer a narrow, well-defined question	Answer a broad or exploratory question. Often the first foray into the literature on the research area.	Answer a broad or exploratory question. Often the first foray into the literature on the research area.
Protocol registered?	Strongly suggested	No	Strongly suggested
Scope	1. Describe the feasibility and  effectiveness of a clinical intervention	1. Describe the nature and characteristics of research in a given area	1. Identify the types of evidence in a given area
	2. Critically appraise evidence for level of confidence in conclusion	2. Examine the volume of research in a given area	2. Explain key concepts/definitions in the literature
	3. Inform clinical decision making and patient care	3. Inform research design	3. Identify how research is conducted on a research topic
	4. Comprehensive synthesis of best available evidence	4. Set the agenda for future research	4. Identify key characteristics or factors related to a concept
	5. Identify and critically appraise similar study types	5. Identify and analyze knowledge gaps	5. Identify and analyze knowledge gaps in the literature for future research
Research methods	Systematic; rigorous; documented; replicable	Systematic; rigorous; documented; replicable	Systematic; rigorous, documented, replicable
Searching	Comprehensive and systematic. Best practice includes grey literature. Hand searching may be undertaken	Comprehensive and systematic. Includes grey literature. Hand searching is not undertaken	Comprehensive and systematic. Includes grey literature. Hand searching may be undertaken
Types of studies typically included	Narrow, similar study types	Broad, variable study types	Broad, variable study types
Risk of Bias Assessment	Required	Optional	Optional
Standardized data extraction forms	Yes	Limited coding of study and intervention characteristics	Yes
Reporting Guideline	PRISMA 2020	PRITEM (protocol) PRISMA-EGM (protocol)	PRISMA-ScR
Presentation of results	Tables, charts, narrative text	Often databases and visualizations	Tables, charts, narrative text
Data charting		Use of published frameworks to guide data mapping	Data charting can be inductive or deductive

What is a Scoping Review?

Scoping Reviews were first formally described as a form of publication in 2001 by Mays et al. 

 

Scoping reviews answer broad research questions or multiple related research questions. Scoping reviews are an initial dive into the literature on a given topic that is not yet known and understood. Scoping Reviews provide an overview of a research topic and may include varied research methodologies, theoretical orientations and more.

 

Why conduct a Scoping Review?

Scoping reviews are especially useful when: 

1. You have a broad and/or multi-faceted research question
2. The research literature is heterogenous or complex
3. You will include studies that use multiple research methodologies, and/or
4. You are completing the first evidence synthesis on a research topic

 

Scoping Review Goals

1. Identify and create an overview of key concepts in the literature on a broad topic
2. Examine the amount (breadth or depth) of research literature on a broad topic
3. Describe the scope, types and nature of research and evidence on a broad topic
4. Identify knowledge gaps in the existing literature for future research projects, including systematic reviews

 

Scoping Review Research Question Framework

PEO: Population / Exposure / Outcome

or 

PCC: Population / Exposure / Outcome

• Population
• Concept - Interventions, Phenomena, or Outcomes of interest 
• Context - Examples may include health setting (primary care, emergency care, nursing/care home)

 

Common mistakes researchers can make when giving Scoping Review research consultations

1. Researchers may want to do a Systematic Review; however, their research question and/or literature types match a Scoping Review or other evidence synthesis type
2. Researchers may believe that a Scoping Review is faster or easier than a Systematic Review or Meta-Analysis
3. Researchers may believe that a Scoping Review is lower impact than a Systematic Review or Meta-Analysis

What is a Mapping Review?

A Mapping Review is:

 

Mapping Reviews are unique in that they feature a previously published data extraction framework as the basis for any map or visualization produced. Methodologies are still under development for this evidence synthesis modality.  Several characteristics of mapping reviews distinguish them from other types of reviews.

Both Mapping Reviews and Scoping Reviews look for knowledge gaps, which are likely areas for future research, or knowledge clusters, which are likely areas of focus for future evidence synthesis research projects. While Scoping Reviews report findings in a narrative or tabular descriptive overview, Mapping Reviews frequently result in databases and visualizations called Evidence or Gap Maps that allow readers the ability to sort data by facets.  These databases can be used by policy makers to understand the research landscape, used by those looking for best practices that have emerged across a body of literature, or used by granting agencies to determine areas where further funding is needed.

Khalil et al (2022) has a very useful reflection on the similarities and differences between mapping reviews and scoping reviews.

Comparison Chart of Scoping Reviews Mapping Reviews, and Evidence or Gap Maps

 

JBI Manual for Evidence Synthesis. The Big Picture Review Family. Infographic: Scoping Reviews, Mapping Reviews, and Evidence and Gap Maps explained. Retrieved February 23, 2025 from https://jbi-global.atlassian.net/wiki/spaces/MANUAL/pages/355863402/Scoping+Review+Resources

1. Arksey, H and O'Malley, L orcid.org/0000-0002-5340-4549 (2005) Scoping studies: towards a methodological framework. International Journal of Social Research Methodology. pp. 19-32 https://eprints.whiterose.ac.uk/1618/1/Scopingstudies.pdf 
2. Campbell, F., Tricco, A.C., Munn, Z. et al. Mapping reviews, scoping reviews, and evidence and gap maps (EGMs): the same but different— the “Big Picture” review family. Syst Rev 12, 45 (2023). https://doi.org/10.1186/s13643-023-02178-5
3. Canadian Institute of Health Research. "A Guide to Knowledge Synthesis" Prepared by J Grimshaw https://cihr-irsc.gc.ca/e/41382.html
4. Khalil, H., & Tricco, A. C. (2022). Differentiating between mapping reviews and scoping reviews in the evidence synthesis ecosystem. Journal of clinical epidemiology, 149, 175–182. https://doi.org/10.1016/j.jclinepi.2022.05.012
5. Khalil, H., Campbell, F., Danial, K., Pollock, D., Munn, Z., Welsh, V., Saran, A., Hoppe, D., & Tricco, A. C. (2024). Advancing the methodology of mapping reviews: A scoping review. Research synthesis methods, 15(3), 384–397. https://doi.org/10.1002/jrsm.1694
6. Lockwood, C., Dos Santos, K. B., & Pap, R. (2019). Practical Guidance for Knowledge Synthesis: Scoping Review Methods. Asian nursing research, 13(5), 287–294. https://doi.org/10.1016/j.anr.2019.11.002
7. Mays N, Roberts E, Popay J. Synthesising research evidence. In: Fulop N, Allen P, Clarke A, Black N, editors. Studying the organisation and delivery of health services: research methods. London, UK: Routledge; 2001
8. Miake-Lye, I.M., Hempel, S., Shanman, R. et al. What is an evidence map? A systematic review of published evidence maps and their definitions, methods, and products. Syst Rev 5, 28 (2016). https://doi.org/10.1186/s13643-016-0204-x
9. Morris, M., Boruff, J. T., & Gore, G. C. (2016). Scoping reviews: establishing the role of the librarian. Journal of the Medical Library Association : JMLA, 104(4), 346–354. https://doi.org/10.3163/1536-5050.104.4.020
10. Peters MDJ, Godfrey C, McInerney P, Munn Z, Tricco AC, Khalil, H. Scoping Reviews (2020). Aromataris E, Lockwood C, Porritt K, Pilla B, Jordan Z, editors. JBI Manual for Evidence Synthesis. JBI; 2024. Available from: https://synthesismanual.jbi.global.  https://doi.org/10.46658/JBIMES-24-09
11. Peters, M. D. J., Marnie, C., Tricco, A. C., Pollock, D., Munn, Z., Alexander, L., McInerney, P., Godfrey, C. M., & Khalil, H. (2020). Updated methodological guidance for the conduct of scoping reviews. JBI evidence synthesis, 18(10), 2119–2126. https://doi.org/10.11124/JBIES-20-00167