Scoping Reviews are gaining popularity in many disciplines as they serve the purpose of identifying the existing literature on a specific research question. They also, clarify concepts in the literature and define gaps in knowledge. Unlike systematic reviews, "...scoping reviews do not aim to produce a critically appraised and synthesised result/answer to a particular question, [they] rather aim to provide an overview or map of the evidence" (Munn et al., 2018).
Scoping Reviews are "systematic-like" however, and require a rigorous approach. They often include a protocol, the searching is systematic and fairly exhaustive and methods are documented thoroughly. They can be the precursor to a full systematic review.
Guidelines and Management
In the health sciences, there are fairly strict guidelines for Scoping Reviews which could be successfully adapted for other disciplines. See:
- Chapter 11 (Scoping Reviews) of the JBI Reviewer's Manual.
- PRISMA for Scoping Reviews, which includes a checklist.
It's a good idea to organise your literature using EndNote groups, as explained in the Organise Your Literature box in this guide.
The PRISMA flow diagram is also useful to help you keep track of studies you've found, and how many of those you have included and excluded (with reasons) during the screening process.
Steps in a Scoping Review
If you're undertaking a Scoping Review in any discipline, the steps in this guide (with a few adjustments) will be useful.
Step 1: Identify your answerable research question - for all types of reviews it's important to pin down your research question. Follow the tips in this guide for trying to decide your focus and then using search frameworks such as PICO or SPIDER to help define your question.
Step 2: Develop your protocol - this step is not always undertaken for a Scoping Review in every discipline, and the PROSPERO protocol database, for example, does not publish Scoping Reviews. However, the JBI Reviewer's Manual states: ... "an a priori protocol must be developed before undertaking the scoping review. A scoping review protocol is important as it pre-defines the objectives, methods and reporting of the review and allows for transparency of process. The protocol should detail the criteria that the reviewers intend to use to include and exclude studies and to identify what data is relevant, and how the data will be extracted and presented. The protocol provides the plan for the scoping review and is important in limiting the occurrence of reporting bias."
Step 3: Conduct systematic searches - all the parts of Step 3 will be useful for Scoping Reviews. Work out a search strategy (including keywords and limitations), decide where to run your searches and be sure to document everything you do carefully and methodically. The JBI Reviewer's Manual suggests you start with an initial search in relevant databases, then analyse the keywords and index terms used in the articles you find to inform a second search using all these terms. Finally check the reference lists of identified reports and studies. It is usual to also search the grey (unpublished) literature.
Step 4: Select studies for inclusion (screening) - you need to work out inclusion and exclusion criteria for all the studies you've found. This will have been outlined in the protocol, if you have one. Otherwise it is usually included in the Methods section of the review. Common exclusion criteria may be the date range, the geographic location of studies, the type of study or the language of publication.
Some guidelines for Scoping Reviews recommend that more than one reviewer goes through the two stages of screening (title/abstract, then full text screening) to reduce the risk of bias. As with all the steps, make sure you record carefully the decisions you make. This could be done on a spreadsheet or table such as in this article by Macvean et al (2017).
Step 5: Critically appraise articles - Munn and his colleagues (2018) state, "Critical appraisal is not mandatory however reviewers may decide to assess and report the risk of bias in scoping reviews".
Step 6: Extract and synthesise the data - as the goal in a Scoping Review is to determine the range of evidence available on a topic, the data is not synthesised in the same way it is for a Systematic Review. Instead, charts, tables and other graphics typically map the results. See again the article by Macvean et al as an example.
Cacchione, P. Z. (2016). The evolving methodology of scoping reviews. Clinical Nursing Research, 25(2), 115-119. doi:10.1177/1054773816637493
Macvean, M., Shlonsky, A., Mildon, R., & Devine, B. (2017). Parenting interventions for indigenous child psychosocial functioning: A scoping review. Research on Social Work Practice, 27(3), 307-334. doi:10.1177/1049731514565668
Munn, Z., Peters, M. D. J., Stern, C., Tufanaru, C., McArthur, A., & Aromataris, E. (2018). Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Medical Research Methodology, 18(1), 143.
Peters, M. D., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., & Soares, C. B. (2015). Guidance for conducting systematic scoping reviews. International Journal of Evidence Based Healthcare, 13(3), 141-146. doi:10.1097/XEB.0000000000000050
Tricco, A. C., Lillie, E., Zarin, W., O'Brien, K. K., Colquhoun, H., Levac, D., . . . Weeks, L. (2018). PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Annals of Internal Medicine, 169(7), 467-473.