What Is a Scoping Review? Definition, Methods and Examples

What is a scoping review? ¶

A scoping review answers "what is out there?" A systematic review answers "what works, and how well?"

A scoping review is a type of evidence synthesis that systematically identifies and maps the available evidence on a broad topic. It describes what kinds of studies exist, which concepts and definitions they use, how research has been conducted and where the gaps are. It does not usually assess study quality or pool results.

The definition in the PRISMA-ScR statement captures the purpose well: scoping reviews map the key concepts underpinning a research area and the main sources and types of evidence available. They are especially useful in emerging or complex fields where the literature is scattered across disciplines and study designs.

So is a scoping review a systematic review? It uses systematic methods, with a protocol, a documented search and transparent selection, but it is a distinct review type with a different purpose. It is also not a meta-analysis, because it rarely combines effect sizes.

When should you choose a scoping review? ¶

Munn and colleagues (2018) set out six common reasons to conduct a scoping review:

1. To identify the types of available evidence in a field.
2. To clarify key concepts or definitions in the literature.
3. To examine how research is conducted on a certain topic or field.
4. To identify key characteristics or factors related to a concept.
5. As a precursor to a systematic review, to check whether one is feasible.
6. To identify and analyze knowledge gaps.

If your question asks whether an intervention works, how accurate a test is or how strongly an exposure is linked to an outcome, you need a systematic review instead. If you simply need background for a thesis chapter, a narrative literature review may be enough.

Scoping review vs systematic review ¶

The two review types share a rigorous process but differ in purpose, scope and output.

A meta-analysis sits at the far end of this spectrum: it is a statistical step within a systematic review, explained in our guide to meta-analysis vs systematic review.

The Arksey and O'Malley framework ¶

Arksey and O'Malley published the first formal scoping review framework in 2005. It has five stages and an optional sixth:

1. Identifying the research question.
2. Identifying relevant studies.
3. Study selection.
4. Charting the data.
5. Collating, summarizing and reporting the results.
6. Consultation exercise (optional), involving stakeholders to inform and validate findings.

In 2010, Levac, Colquhoun and O'Brien recommended enhancements: link the purpose clearly to the question, balance breadth with feasibility, have two reviewers select studies independently, chart data iteratively as a team, add a numerical summary and a qualitative thematic analysis, consider implications for research and practice, and treat consultation as a required stage.

JBI scoping review methodology ¶

JBI (formerly the Joanna Briggs Institute) built on this framework, and its guidance in the JBI Manual for Evidence Synthesis is now the most widely used standard. JBI frames the question with PCC: Population, Concept and Context.

JBI guidance on scoping review protocols (Peters and colleagues, 2022) describes nine steps:

1. Define and align the objectives and questions.
2. Develop and align the inclusion criteria with the objectives and questions.
3. Describe the planned approach to evidence searching, selection, data extraction and presentation.
4. Search for the evidence.
5. Select the evidence.
6. Extract the evidence.
7. Analyze the evidence.
8. Present the results.
9. Summarize the evidence in relation to the purpose, make conclusions and note implications.

Notice the question asks what has been studied and how, not whether the interventions work.

SCOPING REVIEW CHARTING FORM

Review question (PCC):
  Population: 
  Concept: 
  Context: 

Source ID: 
Reviewer: 
Date charted: 

1. Citation details: author(s), year, title, journal or source type
2. Country / region: 
3. Source type: [primary study / review / policy / guideline / grey literature]
4. Aims or purpose: 
5. Study design and methods: 
6. Population: [description, sample size, age, setting]
7. Concept: [how the concept is defined, measured or delivered]
8. Context: [setting, cultural or geographic factors]
9. Outcomes or results relevant to the review question: 
10. Gaps or recommendations noted by authors: 
11. Notes / queries for team discussion: 

Writing a scoping review protocol ¶

A protocol keeps your methods transparent and reduces reporting bias. JBI recommends one for every scoping review and provides a protocol template. Include the title, background, review question with PCC, eligibility criteria, types of sources, a three-step search strategy (an initial limited search, a full search of all databases, then reference list checking), source selection, the draft charting form and the plan for presenting results.

PROSPERO does not register scoping reviews, so most authors register on the Open Science Framework (OSF Registries) or publish the protocol in a journal such as JBI Evidence Synthesis or BMJ Open.

Charting and presenting results ¶

Charting is the scoping review equivalent of data extraction. Typical fields include author, year, country, aims, population, methods, concept details, context, key findings relevant to the question and identified gaps. Results are usually presented as descriptive counts (for example, number of studies by country or design), tables, evidence maps and a short narrative summary. JBI advises against graded recommendations for practice from a scoping review, because the quality of sources was not appraised.

Screening and charting tools such as Covidence and Rayyan work for scoping reviews as well as systematic reviews. In Covidence, you can adapt the extraction template into a charting form. If you need help planning the search or structuring results, our systematic and scoping review support reviews your work with you.

Scoping review example: how the paper is structured ¶

A published scoping review paper usually follows the IMRaD pattern, with sections shaped by PRISMA-ScR. Using the telehealth example above, a typical outline looks like this:

Good scoping review research questions start with words such as "what is known about", "how has" or "what types of". Questions starting with "does" or "how effective" usually signal a systematic review.

Reporting with PRISMA-ScR ¶

PRISMA-ScR (Tricco and colleagues, 2018, Annals of Internal Medicine) is the PRISMA extension for scoping reviews. It contains 20 essential reporting items and 2 optional items. The optional items cover critical appraisal of individual sources of evidence and its results, because appraisal is not required in a scoping review.

The essential items follow the familiar structure: title, structured summary, rationale, objectives, protocol and registration, eligibility criteria, information sources, search, selection of sources, data charting process, data items, synthesis of results, selection of sources of evidence, characteristics of sources, results of individual sources, synthesis of results, summary of evidence, limitations, conclusions and funding. You also report a flow diagram of source selection, laid out like the PRISMA flow diagram.