Scoping Review

A scoping review is a form of evidence synthesis that maps the extent, range, and nature of the literature on a broad topic rather than answering a narrow effectiveness question. It is used to chart what evidence exists, how research on a topic has been conducted, and where the gaps lie, often as a precursor to a systematic review or to inform policy and research planning.

Definition

A scoping review is a structured review that systematically maps the body of literature on a topic — its size, types of evidence, key concepts, and gaps — typically without formally appraising study quality or pooling results to estimate an effect.

Scope

This topic covers the purpose and conduct of scoping reviews: the questions they suit, the staged Arksey and O'Malley framework and its refinements, how they differ from systematic reviews, and the reporting standard PRISMA-ScR. It is a methodological reference, not clinical guidance.

Core questions

• What is the breadth and nature of evidence available on this topic?
• How has research on this topic been conducted and reported?
• What concepts, populations, or interventions have been studied, and which are absent?
• Is a full systematic review warranted, and on what narrower question?

Key concepts

• Mapping the literature
• Broad inclusive research question
• Arksey and O'Malley five-stage framework
• Charting (data extraction) without formal quality appraisal
• Gap identification
• PRISMA-ScR reporting
• Precursor to a systematic review

Mechanisms

A scoping review proceeds through staged steps: identifying a broad research question, identifying relevant studies through systematic searching, selecting studies against inclusive criteria, charting the data, and collating, summarising, and reporting the results — the framework set out by Arksey and O'Malley and refined by Levac and colleagues to add rigour and an optional consultation stage. Unlike a systematic review, it usually maps the evidence without formal risk-of-bias appraisal or meta-analysis, prioritising breadth and description over a pooled effect estimate. Reporting follows the PRISMA-ScR extension (arksey-omalley-2005; levac-2010; tricco-2018-prismascr).

Clinical relevance

Scoping reviews inform health policy and research agendas by showing what is and is not known about a topic, and they often justify and shape subsequent systematic reviews or guidelines. They describe the state of an evidence base rather than estimating treatment effects, so they are not a basis for individual clinical decisions.

Evidence & guidelines

Scoping review methodology is anchored by the Arksey and O'Malley framework, refined by Levac and colleagues, with reporting standardised by PRISMA-ScR; dedicated guidance helps authors decide between a scoping and a systematic review (arksey-omalley-2005; levac-2010; tricco-2018-prismascr; munn-2018; grant-booth-2009).

History

Arksey and O'Malley proposed a methodological framework for scoping studies in 2005, drawing the approach together from earlier mapping practices. Levac and colleagues advanced and clarified the method in 2010, and as scoping reviews proliferated, the PRISMA-ScR reporting extension was published in 2018 to standardise how they are reported and to sharpen the distinction from systematic reviews (arksey-omalley-2005; levac-2010; tricco-2018-prismascr).

Debates

Should scoping reviews appraise study quality?

Because scoping reviews aim to map rather than judge evidence, quality appraisal is usually optional; commentators debate whether omitting it limits usefulness and when a systematic review should be done instead.

Key figures

• Hilary Arksey
• Lisa O'Malley
• Danielle Levac
• Andrea Tricco
• Zachary Munn

Seminal works

• arksey-omalley-2005
• levac-2010
• tricco-2018-prismascr

Frequently asked questions

How does a scoping review differ from a systematic review?

A systematic review answers a focused question and usually appraises study quality and may pool results; a scoping review maps the breadth and nature of evidence on a broader topic, typically without formal quality appraisal or meta-analysis.

When should you choose a scoping review?

When the goal is to survey the extent and types of evidence, clarify concepts, or identify gaps — often before committing to a full systematic review on a narrower question.