Scoping reviews are an increasingly common approach to synthesizing evidence in many fields and, until now, they have been variously defined in the literature.1,2 There is also confusion regarding when to do a scoping review (ie, what are the indications for conducting a scoping review?) and the reasons for selecting this type of evidence synthesis (ie, why choose a scoping review over another type of evidence synthesis?). Our goal in this methodology paper is to provide a universal and clarifying definition for scoping reviews, which is formally supported by the JBI Scoping Reviews Methodology Group. We present the definition, discuss key elements, and propose how to apply the definition in practice.
A definition for scoping reviews
In 2020, the JBI Scoping Reviews Methodology Group began discussing the need for a formal definition for scoping reviews. A first draft was presented to the group, and was deliberated over multiple meetings and through email conversations. After significant modifications and many discussions, a formal consensus was reached on the following definition:
Scoping reviews are a type of evidence synthesis that aims to systematically identify and map the breadth of evidence available on a particular topic, field, concept, or issue, often irrespective of source (ie, primary research, reviews, non-empirical evidence) within or across particular contexts. Scoping reviews can clarify key concepts/definitions in the literature and identify key characteristics or factors related to a concept, including those related to methodological research.
The key elements of this definition are outlined here in more detail:
1. Scoping reviews are a type of evidence synthesis.
Scoping reviews are a review type in the broader family of evidence synthesis.3 They sit alongside other evidence synthesis methodologies such as systematic reviews, qualitative evidence synthesis, realist synthesis, and many more.4-6 Evidence synthesis has been defined as “the review of what is known from existing research using systematic and explicit methods in order to clarify the evidence base.”7(p.2) Evidence synthesis is critical for knowledge translation and to ensure that decisions are based on the best available evidence. As such, they should be performed “systematically”—a reference to the level of rigor and thoroughness of the research process. This is also highlighted within our definition of scoping reviews. To be conducted systematically, scoping reviews require an a priori protocol with a pre-specified objective, question(s), and inclusion/ exclusion criteria; comprehensive searching; protocol-driven screening and selection of included sources; more than one author; and should be conducted following established methodological guidance8,9 and reported using reporting standards, such as the Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews (PRISMA-ScR) guidelines.10
2. Scoping reviews identify and map the breadth of evidence available on a particular topic, field, concept, or issue, often irrespective of source (ie, primary research, reviews, or non-empirical evidence) within or across particular contexts.
There are many reasons that have been provided for conducting a scoping review, although the main one is to explore the breadth of research.1,2 As highlighted in our definition, scoping reviews may aim to identify and map the available evidence on a particular topic or concept, true to their name (ie, scoping). As such, they are exploratory in nature and aim to address wide-ranging questions such as, “What evidence exists?” as opposed to more focused questions such as, “What is effective?” They are also flexible in their approach in terms of their focus area, and allow for investigation of various topics, concepts, or issues across different sources of evidence.
Following the JBI guidance, a key requirement of scoping reviews is to stipulate the “concept” that the reviewers are interested in.8 The concept details the focus and scope of the review in terms of its topic and may include the elements of a standard systematic review, such as interventions, phenomena of interest, and outcomes. However, it may also be a completely different concept unrelated to “interventions” or “phenomena of interest,” and may instead be related to research designs, frameworks, or classifications, for example.
3. Scoping reviews can clarify key concepts/ definitions in the literature, and identify key characteristics or factors related to a concept, including those related to methodological research.
It is important to note that scoping reviews can extend beyond mapping the literature.2 The JBI methods have grouped the purpose of scoping reviews into six broad indications, which are to:11
- 1. identify the types of available evidence in a given field
- 2. clarify key concepts/definitions in the literature
- 3. examine how research is conducted on a certain topic or field
- 4. identify key characteristics or factors related to a concept
- 5. act as a precursor to a systematic review
- 6. identify and analyze knowledge gaps.
Applying the definition
By providing this formal definition proposed by the JBI Scoping Reviews Methodology Group, we aim to improve understanding of scoping reviews and their capabilities. Authors, peer reviewers, journal editors, and knowledge users can all benefit from a shared understanding of what scoping reviews are and how they differ from other types of reviews. This definition can now be used in training and teaching programs, scoping review reports, peer review/editorial guidance, and, ideally, in future updates of methodological guidance and reporting standards.
Declarations
The authors are members of the JBI Scoping Review Methodology Group. ZM is supported by an NHMRC Investigator Grant 1195676. ACT is a member of the JBI Evidence Synthesis editorial advisory board.
References
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2. Tricco AC, Lillie E, Zarin W, O’Brien K, Colquhoun H, Kastner M, et al. A scoping review on the conduct and reporting of scoping reviews. BMC Med Res Methodol 2016;16 (1):1–10.
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8. Peters MDJ, Marnie C, Tricco AC, Pollock D, Munn Z, Alexander L, et al. Updated methodological guidance for the conduct of scoping reviews. JBI Evid Synth 2020;18 (10):2119–2126.
9. Peters M, Godfrey C, McInereney P, Munn Z, Tricco A, Khalil HAromataris E, Munn Z. Chapter 11: Scoping reviews. JBI Manual for Evidence Synthesis [internet]. Adelaide: JBI, 2020 [cited 2022 Feb 28]. Available from:
https://synthesismanual.jbi.global.
10. Tricco AC, Lillie E, Zarin W, O’Brien KK, Colquhoun H, Levac D, et al. PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Ann Intern Med 2018;169 (7):467–473.
11. 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;18 (1):143.
