What is a scoping review?
A scoping review is a structured synthesis that maps the extent, range, and nature of the evidence on a topic. It answers questions about what literature exists, how it is distributed, and where gaps lie — not whether an intervention works. Unlike a systematic review, a scoping review does not appraise the risk of bias in included studies, because its purpose is cartographic rather than evaluative.
The modern scoping review was formalized by Hilary Arksey and Lisa O'Malley in their 2005 paper "Scoping studies: towards a methodological framework" (International Journal of Social Research Methodology). Levac, Colquhoun, and O'Brien extended the framework in 2010 with practical refinements for each of its five stages. The Joanna Briggs Institute (JBI) subsequently published the most detailed current methodology in its Manual for Evidence Synthesis (Peters et al., 2020), which is the canonical methodological reference today.
Reporting follows PRISMA-ScR (PRISMA extension for Scoping Reviews), published by Tricco and colleagues in Annals of Internal Medicine in 2018. PRISMA-ScR adapts the 27-item PRISMA structure to the mapping objectives of a scoping review, notably replacing the risk-of-bias item with an expectation of descriptive charting and thematic mapping.
When to use a scoping review
A scoping review is the right choice when:
- You want to map an emerging or diffuse field. When a topic is new, interdisciplinary, or rapidly evolving, a scoping review identifies what kinds of studies exist, what methods are used, and where the evidence clusters.
- You need to identify gaps to justify a primary study or systematic review. Many funded research programs begin with a scoping review to demonstrate that a gap is real and worth addressing.
- You want to clarify concepts and definitions. Scoping reviews are useful when a term (e.g., "self-management," "resilience," "implementation") is used inconsistently across studies. The review can distil working definitions.
- The question is too broad for a systematic review. Systematic reviews require narrow PICO questions. If the question is "what is known about X?" rather than "does Y work for Z?", a scoping review is a better fit.
- You want to inform guidelines or policy with an evidence map. Decision-makers often need breadth before depth — what the evidence covers, not a pooled estimate.
Contrast with a systematic review (narrow question, risk-of-bias appraisal, may pool), a narrative review (interpretive, no protocol), a rapid review (accelerated systematic methods), and an umbrella review (synthesizes prior reviews).
Step-by-step process
The Arksey and O'Malley / JBI framework lines up cleanly with the five-phase review pipeline:
- Identify the research question and eligibility criteria. A scoping question is broader than a PICO but still specific: population, concept, and context (PCC) is the JBI framework. Draft a protocol and, if your team follows JBI, publish it (Open Science Framework or a journal such as JBI Evidence Synthesis).
- Search strategy. Search comprehensively across databases appropriate to the topic, supplemented by grey literature, conference proceedings, and targeted website searching. Document strings and dates as you would for a systematic review — PRISMA-S applies here too.
- Study selection and screening. Screen in duplicate against the PCC criteria. Scoping reviews typically include a wider variety of study designs than systematic reviews (qualitative, quantitative, grey literature, protocols), so eligibility rules must accommodate that breadth.
- Chart the data (data extraction). Rather than extracting outcomes, you chart descriptive characteristics: study design, population, geographic setting, concept definitions, methods, and key findings. Pilot the charting form on 5–10 studies and refine.
- Collate, summarize, and report results (synthesis). Present the evidence map — often through counts, tables, and visualizations (bubble plots, evidence gap maps) — and discuss implications for practice, policy, or future research. Consult stakeholders where feasible (the optional sixth Arksey/O'Malley stage).
Reporting standards
Report in full compliance with PRISMA-ScR (Tricco et al., 2018), a 20-item checklist covering title, abstract, methods, results, and discussion. Include a PRISMA flow diagram. Do not report a risk-of-bias assessment — scoping reviews do not appraise quality — but be explicit that this is a deliberate methodological choice. Register the protocol on Open Science Framework (scoping protocols are outside the scope of PROSPERO). See the reporting standards overview.
Common pitfalls
- Conflating a scoping review with a systematic review. If you appraise risk of bias and pool effects, you are conducting a systematic review — not a scoping review. Choose the right label.
- Scope creep. "Broad" is not the same as "unbounded." Without clear PCC criteria, a scoping review becomes unfinishable. Pilot the screen before the full run.
- Under-specified charting form. Because you are mapping rather than extracting outcomes, a vague form produces incomparable summaries. Pilot and revise explicitly.
- Skipping the grey literature. Scoping reviews are especially weakened by ignoring reports, theses, and policy documents where emerging topics often live.
- No synthesis beyond description. Counting studies is not enough. The reader needs themes, gaps, and directions — a narrative review style discussion on top of the descriptive map.
Tools & templates
Use the Search Strategy Documentation Form, the Inclusion/Exclusion Criteria Checklist, and the Literature Review Matrix adapted for charting (population, concept, context, methods, key findings). The PRISMA Flow Diagram Template adapts readily to PRISMA-ScR. All are available in the templates library.
Next steps
Scoping reviews reward thoughtful charting more than any other step. A well-designed charting form turns a sprawling literature into an evidence map a reader can grasp in minutes. Pilot your form, revise it early, and keep charting in a structured matrix so you can pivot between tabular summaries and narrative synthesis. The Subthesis Literature Matrix gives you configurable columns tailored to PCC charting.