What Is a Scoping Review? Purpose, Method, Examples

• A scoping review is an evidence synthesis method designed to map the extent, nature, and range of available literature on a topic. It does not answer a specific clinical or policy question.
• It is the appropriate choice when a topic is new, broad, conceptually unclear, or characterised by heterogeneous evidence.
• Unlike systematic reviews, scoping reviews do not require quality appraisal of included studies, allow flexible and broad inclusion criteria, and can include all study types and grey literature.

What Is a Scoping Review?

A scoping review is a type of evidence synthesis that uses a systematic and iterative approach to identify, map, and summarize an existing or emerging body of literature on a given topic. Unlike a systematic review, which is designed to answer a focused, often clinical question, a scoping review is primarily exploratory and tells you what evidence is there and what isn’t. 

Core Characteristics

• Broad, exploratory research question (not a narrow clinical question)
• Systematic and transparent methodology, but more flexible than a systematic review
• Includes all study designs: qualitative, quantitative, and mixed-methods
• Can include grey literature (government reports, theses, policy documents)
• Does not typically perform critical quality appraisal of included studies
• Iterative in nature; the team may revisit earlier steps as understanding deepens
• Output is descriptive: a map of concepts, evidence types, and knowledge gaps
• Can be conducted as a standalone review or as a precursor to a systematic review

Is a scoping review qualitative or quantitative?

A scoping review can include qualitative studies, quantitative studies, or both, and typically presents findings descriptively (charting, tabulating) rather than through statistical pooling.  

A Brief History of Scoping Reviews

The methodology was first formally described by Arksey and O’Malley (2005), drawing on earlier informal uses of scoping approaches in social research. It was subsequently refined by Levac, Colquhoun, and O’Brien (2010), and later formalised into institutional guidance by the Joanna Briggs Institute (JBI). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist, published in 2018, further standardised how scoping reviews are planned and reported.

What Is the Purpose of a Scoping Review?

Scoping reviews serve several distinct and complementary purposes. According to Arksey and O’Malley and subsequent methodologists, the main reasons for conducting a scoping review include:

• To identify the types of available evidence in a given field
• To clarify key concepts and definitions that are contested or inconsistently used across the literature
• To examine how research has been conducted on a topic, including methodological diversity
• To identify key characteristics or factors related to a concept
• To identify and analyse gaps in the existing knowledge base
• To provide a precursor to a systematic review, determining whether one is warranted and refining its scope
• To summarise and disseminate research findings for practitioners, policymakers, and researchers

Importantly, scoping reviews are not designed to answer clinical questions about the effectiveness or safety of interventions. They provide descriptive summaries and evidence maps. The conclusions from a scoping review cannot directly guide clinical practice or policy. 

When Should You Conduct a Scoping Review?

Here are the situations in which a scoping review is the appropriate choice:

Situation	Why a Scoping Review Fits
The topic is new or emerging and lacks comprehensive review	A scoping review is ideal when evidence is sparse, varied, or still accumulating (e.g., COVID-19 in early 2020).
The research question is broad and exploratory	If the question asks ‘what is known about X?’ rather than ‘does X work?’, a scoping review is the appropriate choice.
Definitions or concepts are unclear or contested	Scoping reviews help clarify how key terms are used across the literature before embarking on more focused research.
You need to map heterogeneous evidence across study types	Unlike systematic reviews, scoping reviews can include qualitative, quantitative, and mixed-methods studies without methodological restriction.
You want to determine if a systematic review is warranted	A scoping review can confirm whether sufficient and sufficiently homogeneous literature exists to support a formal systematic review.
You want to identify research gaps to inform future priorities	Identifying what has not been studied is a primary output of a scoping review.
You are a practitioner or policymaker seeking a landscape overview	Scoping reviews are useful for staying informed about an evolving field without needing definitive clinical guidance.

When Should You Not Conduct a Scoping Review?

Conversely, a scoping review is NOT the right choice when:

• You need a definitive, clinically actionable answer (use a systematic review instead)
• Your question is already well-defined, narrow, and addressable through focused synthesis
• You want to formally assess the strength or quality of evidence to guide practice guidelines
• You are trying to avoid the rigour of a systematic review. Scoping reviews require their own rigour

Scoping Review Vs Systematic Review vs Narrative Review

Feature	Scoping Review	Systematic Review	Narrative Review
Purpose	Map literature, identify gaps, clarify concepts	Answer a specific clinical/policy question	Summarise a topic descriptively
Research Question	Broad, exploratory, open-ended	Narrow, focused, pre-defined (PICO)	Variable; no fixed structure
Protocol Required	Yes, pre-specified	Yes, pre-specified & often registered on PROSPERO	No
Quality Appraisal	Optional	Mandatory; risk-of-bias assessed	Not required
Inclusion Criteria	Broad; heterogeneous studies welcome	Strict; specific study designs	Informal
Grey Literature	Included	Sometimes included	Rarely formal
Team Size	Small (2+ reviewers recommended)	Large, multi-disciplinary team	Usually 1 person
Time Commitment	Months (avg. 6–12 months)	Long (12–18+ months)	Short to moderate
Level of Evidence	Moderate	Highest	Low
Informs Practice/Policy?	Indirectly (describes landscape)	Directly (evidence-based guidance)	Broadly informative only
Reporting Standard	PRISMA-ScR	PRISMA + GRADE	None mandatory
Output	Evidence map, conceptual overview, gap analysis	Synthesised conclusions, meta-analysis possible	Narrative summary

How to Conduct a Scoping Review: A Step-by-Step Guide

The steps involved in conducting a scoping review were first described in the Arksey and O’Malley framework (2005), refined by Levac et al. (2010) and the JBI methodology. The process is iterative. Teams may move backwards to earlier steps as their understanding of the topic evolves.

Developing the Research Question

A well-formed research question is the foundation of a successful scoping review. JBI recommends using the PCC framework:

• Population: who is the focus? (e.g., adults with Type 2 diabetes; undergraduate nursing students)
• Concept: what is the key phenomenon, intervention, or issue being mapped?
• Context: in what setting, culture, or geographic context? (e.g., primary care in low-income countries)

Example:

A well-formed scoping review question might be: ‘What blended learning approaches are currently used in undergraduate nursing education?’. This is broad enough to encompass diverse approaches but specific enough to be answerable and bounded.

Building the Search Strategy

A comprehensive, multi-database literature search is essential for a scoping review. You must

• Search at least two to three databases relevant to your field. In healthcare, common choices include PubMed/MEDLINE, EMBASE, CINAHL, Scopus, and Web of Science.
• Use Boolean operators (AND, OR, NOT) to combine search terms systematically.
• Use controlled vocabulary and field tags (e.g., title, abstract) to increase precision.
• Search grey literature sources including Google Scholar, government websites, policy repositories, and institutional repositories.
• Consider manual searching of reference lists of included studies (snowballing).
• Involve a librarian: their expertise in database structure and search strategy design is invaluable, and many journals now expect librarian involvement in the search process.

Screening and Calibration

Screening involves two phases: an initial screen of titles and abstracts, followed by a full-text review of potentially eligible studies. A critical aspect of rigorous screening is calibration:

1. Select 5–10% of the total papers for independent screening by two reviewers.
2. Compare decisions and calculate the level of agreement. A threshold of ≥90% agreement is commonly used.
3. Discuss any disagreements to align on the interpretation of inclusion criteria.
4. If agreement is below threshold, revise the criteria and repeat with another 10% sample.
5. After achieving satisfactory agreement, proceed with full screening: either with dual review or with one primary reviewer and a second verifying a proportion of decisions.

 

Charting the Data

Data charting is the scoping review equivalent of data extraction. Key fields typically captured include:

• Author(s) and year of publication
• Country or geographic setting
• Study aims and design
• Population and sample size (if applicable)
• Intervention type, comparator, and outcome measures (if applicable)
• Key findings relevant to the scoping review question
• Study limitations and future directions noted by authors

The charting form must be developed collaboratively and pilot-tested on a small sample (5–10 papers) before full use. Calibration between reviewers is also required at this stage.

Synthesis and Reporting

Once data are charted, the team conducts both numerical and thematic analysis:

• Numerical analysis: frequency counts, distribution of publication years, country of origin, study designs, journals. Results are presented in tables or figures.
• Thematic analysis: codes are applied to key excerpts of text, then grouped into categories and themes. This process is iterative and reflexive, guided by memos and team discussion.

All scoping reviews should be reported using the PRISMA-ScR checklist, which includes a mandatory PRISMA flow diagram documenting the number of records identified, screened, and included at each stage.

PRISMA-ScR Checklist

PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) is a reporting guideline to ensure scoping reviews are transparent, complete, and reproducible.

What is it?

• An extension of the original PRISMA checklist, tailored specifically for scoping reviews
• Published in 2018 in Annals of Internal Medicine
• Contains 20 essential items + 2 optional items across 6 sections

The 6 Sections & Key Items

Section	Key Items
Title	Identify the report as a scoping review
Abstract	Structured summary including objectives, eligibility criteria, sources, methods, results
Introduction	Rationale for the review; explicit research question
Methods	Protocol registration, eligibility criteria, information sources, search strategy, selection process, data extraction, data items, critical appraisal (optional)
Results	Study selection (with PRISMA flow diagram), characteristics of sources, critical appraisal results (optional), results of individual sources, synthesis of results
Discussion & Conclusion	Summary, limitations, conclusions, implications for future research

Common Pitfalls in a Scoping Review: Dos and Don’ts

Scoping reviews are sometimes misused: either conducted inappropriately (when a systematic review was warranted) or conducted poorly (skipping calibration, using a single reviewer, failing to register a protocol). The following table summarises the key dos and don’ts:

Do	Don’t
Do conduct a scoping review when the field is new, broad, or conceptually unclear	Don’t conduct one solely to avoid the rigour of a systematic review
Do include grey literature and diverse study designs	Don’t restrict to a single study design as you would in a systematic review
Do assemble a team of at least 2 reviewers for screening and extraction	Don’t rely on a single reviewer for the full screening process
Do register your protocol in a public registry before starting	Don’t begin searching before finalising your research question and protocol
Do use PRISMA-ScR to guide reporting	Don’t report a scoping review using general narrative review conventions
Do conduct a calibration exercise before full screening	Don’t skip calibration: poor inter-rater agreement compromises validity
Do include stakeholder consultation when possible	Don’t make definitive clinical or practice recommendations based solely on a scoping review

JBI Methodology for Scoping Reviews

The Joanna Briggs Institute provides a comprehensive manual for scoping reviews, including a template for developing protocols, step-by-step procedural guidance, and a data charting template. JBI methodology is particularly prevalent in nursing and allied health research but is applicable across disciplines.

Core Steps (JBI 6-Stage Process)

Stage	Action
1. Define the question	Use PCC to frame a clear, answerable scoping question
2. Develop a protocol	Pre-register on OSF or JBI SUMARI before starting
3. Search the literature	Conduct a three-step search (see below)
4. Select studies	Screen titles/abstracts, then full text — minimum 2 independent reviewers
5. Extract data	Use a standardised data extraction tool; piloted before use
6. Synthesise & report	Narrative synthesis; report using PRISMA-ScR checklist

The JBI Three-Step Search Strategy

• Step 1, Initial search: Search 2 databases (e.g., MEDLINE, CINAHL) using key terms; analyse keywords from titles, abstracts, and index terms
• Step 2, Full search: Apply all identified keywords and MeSH terms across all relevant databases
• Step 3, Reference lists: Screen reference lists of all included sources for additional studies

Protocol Registration of Scoping Reviews

It is considered best practice (and sometimes a journal requirement) to register the scoping review protocol before beginning the search. The Open Science Framework (OSF) and PROSPERO are the two most commonly used registries. Registration:

• Locks in the research question, eligibility criteria, and planned analysis before data collection
• Reduces the risk of outcome reporting bias
• Demonstrates methodological rigour to peer reviewers and editors
• Allows other researchers to identify that a review is underway, preventing duplication

Frequently Asked Questions

Can I conduct a scoping review on my own, or do I always need a team?

Technically, a scoping review can be completed by a single person, and some earlier scoping reviews in the literature were conducted this way. However, current best-practice guidance from the JBI, PRISMA-ScR, and the broader methodological literature strongly recommends a minimum of two reviewers, particularly for the screening and data charting stages. Single-reviewer screening introduces bias and reduces reliability.

The calibration exercise, which requires independent screening by two reviewers on a subset of papers and comparison of decisions, is also not possible with a solo researcher. Many journals now explicitly require dual review as a condition of publication.

If resources genuinely do not permit a full team, one approach is to have a primary reviewer conduct all screening, with a second reviewer verifying a meaningful proportion (often at least 20%) of decisions. Always be transparent about team composition in your methods section.

Is a scoping review ‘lower quality’ or ‘less rigorous’ than a systematic review?

No, with an important caveat. A scoping review is not a lesser or inferior version of a systematic review. A scoping review is a different tool designed for a different purpose.

Conducting a rigorous scoping review demands its own form of methodological discipline: a pre-specified protocol, systematic multi-database searching, calibrated dual screening, structured data charting, and transparent reporting via PRISMA-ScR. A well-conducted scoping review is a valid and publishable scholarly contribution.

Nevertheless, scoping reviews do sit at a lower level of evidence than systematic reviews when it comes to making clinical or policy recommendations, because they do not include critical quality appraisal or formal synthesis of evidence strength. They are powerful for mapping and exploration; they are not appropriate as a basis for changing clinical practice.

Do I need to do quality appraisal in a scoping review?

Formal critical appraisal, i.e., assessing the methodological quality and risk of bias of each included study, is generally not required in a scoping review. This is one of the defining methodological differences between scoping and systematic reviews.

The rationale is that a scoping review aims to provide an inclusive map of the available literature, regardless of the quality of individual studies; a methodologically weak study may still be relevant for illustrating how a concept has been discussed or what populations have been studied.

That said, some researchers choose to include quality appraisal as an optional additional step, particularly if a scoping review is being designed to closely inform practice or policy, or if a specific journal requires it.

How long does a scoping review take, and how many articles will I need to screen?

The honest answer is: longer than most people expect, and more articles than most people anticipate. From initial question development through to a submitted manuscript, a scoping review commonly takes between 6 and 18 months.

The literature search itself can typically be completed in 4–6 weeks with librarian support, but the screening, data charting, analysis, and writing phases are substantial. The number of articles to screen depends heavily on how broad your research question is and the novelty of the topic.

What is the difference between a mapping review and a scoping review?

While both aim to map existing evidence and identify gaps, they differ in purpose and depth.

A mapping review (also called an evidence or systematic map) focuses on categorizing and characterizing the literature. It identifies the volume, types, and distribution of research on a broad topic, often presenting results visually or in tables. The emphasis is on charting where research clusters and where gaps exist, rather than examining findings in detail. It frequently informs future systematic reviews.

A scoping review typically addresses a somewhat more focused question. Beyond mapping breadth, it clarifies key concepts, examines how research is conducted, and often provides a narrative synthesis of the nature of the evidence. It follows established guidance (Arksey & O’Malley; JBI) and PRISMA-ScR reporting standards.

In short: mapping reviews emphasize categorization and distribution, while scoping reviews go somewhat deeper into interpreting the evidence. Terminology often overlaps in practice.

What is the difference between a scoping review and a realist review?

A scoping review maps the breadth and nature of existing evidence on a topic: what has been studied, where, and how. It does not synthesize findings to answer a causal question. A realist review, by contrast, is theory-driven and explanatory: it asks why an intervention works, for whom, and in what circumstances, producing refined Context, Mechanism, Outcome (CMO) configurations. Scoping reviews suit unfamiliar fields where the literature needs charting; realist reviews suit complex interventions where mechanism and context need explaining. Scoping reviews describe the evidence landscape; realist reviews build causal theory from it.

What is the difference between a scoping review and a meta-analysis?

The key differences between a scoping review and a meta-analysis are as follows:

Aspect	Scoping Review	Meta-analysis
Purpose	Map breadth of evidence, identify gaps	Estimate a pooled effect size
Question	Broad (“what exists?”)	Narrow, focused (specific PICO)
Study types	Any design, qualitative or quantitative	Comparable quantitative studies only
How literature is synthesized	Descriptive charting/tabulation	Statistical pooling with heterogeneity testing