Scoping reviews and evidence maps
Why this level?
Specify the research question: intervention, diagnostic accuracy, prognosis, aetiology, or screening intervention. Other question types are outside this hierarchy. NHMRC 2009 sourceA scoping review maps evidence across designs; its study count does not confer the evidence level of a systematic review estimating a particular intervention effect.
The question
A scoping review can map concepts, study types, populations, measures and the extent of evidence across a broad question. An evidence map presents the distribution of evidence across explicitly defined dimensions. Define the purpose of the map and what each cell or category means; the labels do not prescribe one universal method.
When it helps
Use this approach to clarify concepts, identify how a field has been studied, or establish whether a more focused systematic review is feasible. Broad or heterogeneous evidence can be appropriate when describing that heterogeneity is part of the question.
When another review is needed
If the aim is to decide whether an intervention improves an outcome, use a review method suited to estimating effects, risk of bias and certainty. A scoping review without those components cannot supply the same answer. A rapid search yielding few records does not establish that evidence is absent.
Plan a reproducible review
- Specify population, concept and context, eligibility, information sources and a protocol before screening.
- Develop and document a search appropriate to the question, including relevant databases, dates, language limits and grey literature where justified.
- Use a transparent selection process and a piloted charting form. Explain reviewer roles, disagreements and amendments.
- State whether critical appraisal is appropriate to the purpose, how it is done, and how its absence limits the conclusions.
- Distinguish studies from reports of the same study, and distinguish evidence quantity from evidence quality.
Present the map honestly
Display the populations, designs or measures relevant to the review question, with denominators and definitions. Empty cells may reflect search limits, classification choices or unpublished work. Describe those uncertainties before proposing a new study. PRISMA-ScR supports reporting; methodological conduct still needs a protocol and appropriate review methods.
Record in the workspace
Record the map’s purpose, protocol, search and screening responsibilities, classification framework, planned charting, appraisal decision and intended interpretation. Attach the resulting evidence questions to the relevant research aim instead of treating search counts as a novelty verdict.
What to watch out for
A map of published studies is not an estimate of treatment benefit or proof of a research gap. Counts depend on the search, eligibility, classification and appraisal choices.
- PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation (opens in a new tab) · Ann Intern Med · doi 10.7326/M18-0850
- Updated methodological guidance for the conduct of scoping reviews (opens in a new tab) · JBI Evid Synth · doi 10.11124/JBIES-20-00167