Before embarking on an evidence synthesis project, it is important to understand what type of review is most suitable for your research question. Choosing the wrong review type for your question can lead to frustrating results.
The ultimate goal of a systematic review is to “collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question.”[1] While scoping reviews are typically used to identify the types of evidence in a given field, or to identify and analyze knowledge gaps.[2] Using a scoping review type question for a systematic review tends to lead to a larger-than-expected number of results.
Systematic and scoping reviews share some common methods, but they are used for fundamentally different types of questions. Here is a breakdown of some of their major differences:
[1] Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org., Section 1.2.2
[2] Munn Z, Peters MDJ, Stern C, Tufanaru C, McArthur A, Aromataris E. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Med Res Methodol. 2018 Nov 19;18(1):143. doi: 10.1186/s12874-018-0611-x. PMID: 30453902; PMCID: PMC6245623.
| Scoping Reviews | Systematic Reviews | |
| Type of Question | Broad topic, usually determining the scope or coverage of a topic in the body of literature | Narrow, well-defined topic. Attempting to find and collate all evidence to answer a specific question. |
| Typical Question Outline | PCC (Population, Concept, Context) | PICO (Problem/population, Intervention, Comparison Intervention, Outcome) |
| Search Strategies | Detailed search strategies that include a combination of controlled vocabulary terms (MeSH, Emtree), and keyword terms. | Detailed search strategies that include a combination of controlled vocabulary terms (MeSH, Emtree), and keyword terms. |
| Publication Type Inclusion | Sources can vary (i.e. primary research, reviews, non-empirical evidence).[3] | Empirical evidence after structured assessment of quality. |
| Use of filters/limits (e.g. date limits, language limits, etc.) | Generally okay to use, depending on the research question and the goals for the scoping review. | Generally discouraged unless used for reasons that can be clearly explained in search methodology (e.g. using a date limit to exclude surgical techniques no longer in use). |
| Protocol Registration | Open Science Framework (OSF) | PROSPERO |
| Meta-Analysis (statistical synthesis of evidence) | Not usually done | Can be done if data from studies are homogenous enough to combine. |
| Grey Literature Search | Not usually included | Usually included |
| Reporting Standard | PRISMA-ScR | Standard PRISMA |
| Example Question | What research is available about non-pharmaceutical treatments for ADHD? | Is cognitive behavior therapy an effective treatment for adolescents with ADHD? |
[3] Munn Z, Pollock D, Khalil H, Alexander L, Mclnerney P, Godfrey CM, Peters M, Tricco AC. What are scoping reviews? Providing a formal definition of scoping reviews as a type of evidence synthesis. JBI Evid Synth. 2022 Apr 1;20(4):950-952. doi: 10.11124/JBIES-21-00483. PMID: 35249995.
Still not sure which type of review is right for your research? You can try the Right Review tool to help guide you: https://rightreview.knowledgetranslation.net/
You can also discuss your research question with Becker Library’s systematic review team. Our librarians have worked on systematic and scoping reviews for over a decade and can provide advice and guidance for your project. Contact us at askbecker@wustl.edu
Here are some additional resources from Becker Library to help with your systematic or scoping review projects:
- Systematic Review Guide: https://beckerguides.wustl.edu/SystematicReviews
- Scoping Review Guide: https://beckerguides.wustl.edu/scopingreviews