The choice between a scoping review and a systematic review is the most consequential decision a researcher makes before any searching begins, and it is frequently made for the wrong reasons. Candidates sometimes choose a scoping review because it appears faster or because it avoids the statistical demands of meta-analysis, then discover at examination or peer review that their question requires the focused answer a systematic review provides. Others launch a systematic review on a broad, emerging, or heterogeneous topic where the evidence cannot yet support a synthesis, when a scoping review should first have mapped the terrain. The two review types answer fundamentally different questions, follow different methods, and register in different places. Choosing correctly at the outset determines whether the review can be completed, published, and defended. Our scoping review service and systematic review writing service support both, but the decision between them comes first.
This guide sets out the authoritative distinction as defined by JBI and the PRISMA extension for scoping reviews, the specific indications for each review type, and the practical differences in question framework, critical appraisal, registration, and reporting that follow from the choice.
Quick Answer:
Conduct a systematic review when you have a focused question, typically about the effectiveness or feasibility of an intervention, that you intend to answer definitively by appraising and synthesizing the evidence. Conduct a scoping review when your purpose is to map the extent, range, and nature of the evidence on a broader topic: to identify the types of available evidence, clarify concepts or definitions, examine how research is conducted, or identify knowledge gaps. Systematic reviews use PICO, conduct a critical appraisal of included studies, and register on PROSPERO. Scoping reviews use PCC (Population, Concept, Context), generally do not require critical appraisal, follow the PRISMA-ScR reporting guideline, and cannot be registered on PROSPERO, which does not accept them; scoping protocols are registered on OSF or Figshare or published instead.
The Core Distinction: Different Questions, Not Different Effort
The most damaging misconception is that a scoping review is a lighter or preliminary form of a systematic review. It is not. A scoping review is a distinct form of evidence synthesis with its own purpose, and it is often as demanding to conduct well. The difference is not one of rigor but of aim.
A systematic review answers a specific, well-defined question by locating all relevant studies, appraising their quality, and synthesizing their findings, often quantitatively through meta-analysis. Its output is an answer: this intervention does or does not produce this outcome, with this degree of certainty. A scoping review addresses a broader question by mapping what evidence exists and how it is distributed. Its output is a map: this is the range of evidence available, these are the concepts in use, these are the gaps. As Munn and colleagues put it in their authoritative 2018 guidance in BMC Medical Research Methodology, a scoping review is appropriate where the purpose is to identify knowledge gaps, scope a body of literature, clarify concepts, or investigate how research is conducted, rather than to answer a single focused question of effectiveness.
This distinction determines everything downstream. Because a systematic review answers a question about effectiveness, it must appraise the risk of bias in its included studies, since the answer is only as trustworthy as the studies producing it. Because a scoping review maps evidence rather than answering an effectiveness question, critical appraisal is generally not required. The choice of review type is therefore not a choice of how much work to do, but of what question you are entitled to answer at the end. Our overview of systematic review versus meta-analysis versus scoping versus narrative review situates both within the wider family of synthesis types.
Table 1: Scoping Review vs Systematic Review at a Glance
Feature | Scoping Review | Systematic Review |
|---|---|---|
Purpose | Map the extent, range, and nature of evidence | Answer a focused question, often effectiveness |
Question framework | PCC (Population, Concept, Context) | PICO (Population, Intervention, Comparator, Outcome) |
Critical appraisal | Generally not required (JBI) | Required (RoB 2, ROBINS-I, or design-appropriate tool) |
Synthesis | Descriptive mapping and charting | Narrative or quantitative (meta-analysis) |
Registration | OSF or Figshare; NOT PROSPERO | PROSPERO |
Reporting guideline | PRISMA-ScR (Tricco et al., 2018) | PRISMA 2020 (Page et al., 2021) |
The Frameworks Behind Scoping Reviews
Scoping review methodology has a clear lineage that examiners expect a candidate to know. The framework originated with Arksey and O'Malley in 2005, who proposed a five-stage process: identifying the research question; identifying relevant studies; study selection; charting the data; and collating, summarizing, and reporting the results. They also proposed an optional sixth stage, a consultation exercise with stakeholders to add perspectives beyond the literature.
Levac, Colquhoun, and O'Brien refined this framework in 2010, addressing ambiguities in the original. Their refinements included linking the research question explicitly to the purpose of the review, adopting an iterative and team-based approach to study selection and data charting, and recommending that the consultation stage be treated as a required component rather than an optional one, because of its value for knowledge translation.
JBI, formerly the Joanna Briggs Institute, built on both to produce the current standardized methodology, set out by Peters and colleagues and codified in Chapter 11 of the JBI Manual for Evidence Synthesis. This is now the most widely used methodological guidance for conducting scoping reviews, and it is the source a candidate should cite for current practice. The reporting of scoping reviews is governed separately by the PRISMA extension for scoping reviews, PRISMA-ScR, published by Tricco and colleagues in Annals of Internal Medicine in 2018, which specifies the items a scoping review report must contain. The methods of conducting a scoping review to this standard are covered in our guide on how to write a scoping review with PRISMA-ScR.
When a Scoping Review Is the Right Choice
JBI and Munn and colleagues set out specific indications for a scoping review, and a candidate whose purpose matches one of these has a defensible case for the design. A scoping review is appropriate when the aim is to identify the types of available evidence in a field; to clarify key concepts or definitions in the literature; to examine how research on a topic is conducted, including the methods and designs used; to identify key characteristics or factors related to a concept; to serve as a precursor to a systematic review, confirming that the volume and nature of the evidence justify one; or to identify and analyze knowledge gaps.
The common thread is mapping rather than answering. If the honest purpose of the review is to survey a broad or emerging field and describe what is there, a scoping review fits. If the purpose is to determine whether something works, it does not. The precursor function deserves particular note, because it is a legitimate and common reason to conduct a scoping review first: where a field is too broad or heterogeneous to know whether a systematic review is feasible, a scoping review maps the evidence and establishes whether a focused, appraisable body of studies exists to support a subsequent systematic review.
Table 2: When to Choose a Scoping Review (JBI / Munn et al. Indications)
Indication | Example Purpose |
|---|---|
Identify types of available evidence | What kinds of studies exist on this emerging topic? |
Clarify concepts or definitions | How is this concept defined across the literature? |
Examine how research is conducted | What methods and designs are used to study this? |
Identify key characteristics or factors | What factors are associated with this concept? |
Precursor to a systematic review | Is there enough comparable evidence to justify one? |
Identify and analyze knowledge gaps | Where is evidence missing in this field? |
When a Systematic Review Is the Right Choice
A systematic review is the correct design when the review has a focused question that it intends to answer definitively, most commonly a question of effectiveness, but also of feasibility, appropriateness, meaningfulness, diagnostic accuracy, prognosis, or etiology. The defining features are a narrow, answerable question; predefined eligibility criteria; a comprehensive search; critical appraisal of the included studies; and a synthesis, often quantitative, that produces an answer with an associated degree of certainty.
If the question can be framed as whether a defined intervention produces a defined outcome in a defined population compared with a defined comparator, and the intent is to answer it, a systematic review is required, and a scoping review would not satisfy the reader who needs that answer. The rigor of the systematic review, its appraisal of study quality, and its careful synthesis are precisely what license the definitive conclusion. Our step-by-step guide to writing a systematic review covers this process in full.
PCC Versus PICO: The Question Framework Follows the Review Type
The question framework is the first concrete point at which the two review types diverge, and using the wrong one signals a misunderstanding of the design.
Systematic reviews of effectiveness use PICO: Population, Intervention, Comparator, and Outcome. The comparator and the outcome are essential because the review is comparing one course of action against another and measuring a defined result. The specificity of PICO is what makes the question answerable.
Scoping reviews use PCC: Population, Concept, and Context. JBI is explicit that a scoping review does not require an explicit intervention, comparator, or outcome to be stated, because it is not comparing interventions or measuring effects. The Concept is the broad idea being mapped, and the Context situates it. The absence of a comparator and a defined outcome is not a weakness of the scoping question; it is a direct consequence of the review's mapping purpose. A candidate who forces a scoping review into a PICO framework, complete with comparator and outcome, has usually either misunderstood the design or should be conducting a systematic review instead.
Critical Appraisal: The Difference That Follows From Purpose
Whether the review appraises the risk of bias in its included studies is one of the clearest practical differences, and it follows directly from what each review claims to produce.
A systematic review must conduct a critical appraisal. Because it answers a question about effectiveness or another defined outcome, the trustworthiness of its answer depends on the internal validity of the studies it synthesizes, appraised with a design-appropriate tool such as RoB 2 for randomized trials or ROBINS-I for non-randomized studies. Omitting appraisal in a systematic review is a serious methodological flaw.
A scoping review generally does not require critical appraisal, per JBI guidance. Because it maps the evidence rather than answering an effectiveness question, the risk of bias in individual studies does not bear on its output in the same way. This does not make a scoping review easier; it makes it different. A scoping review may still describe the methodological characteristics of the evidence it maps, but it is not obliged to appraise and weight studies by their risk of bias, because it draws no effectiveness conclusion that would depend on that weighting.
Registration and Reporting: Where the Two Diverge Formally
The final practical divergence, and one that catches many researchers unprepared, concerns registration. Prospective registration of a review protocol is expected practice, but the two review types are registered in different places, and this is not a matter of preference.
PROSPERO, the international prospective register of systematic reviews maintained by the Center for Reviews and Dissemination at the University of York, accepts systematic reviews, rapid reviews, and umbrella reviews. It does not accept scoping reviews or literature scoping exercises. A researcher who has decided on a scoping review and attempts to register it on PROSPERO will have the registration declined. Scoping review protocols are instead registered on the Open Science Framework or Figshare, or published as a protocol in a journal such as JBI Evidence Synthesis or BMJ Open. Getting this right requires deciding the review type before attempting registration, which is one reason the decision cannot be deferred; our protocol and PROSPERO registration service, and our guide on writing a protocol and registering on PROSPERO address the systematic review pathway specifically.
Reporting standards differ correspondingly. A systematic review is reported according to PRISMA 2020, the 27-item checklist for reporting systematic reviews. A scoping review is reported according to PRISMA-ScR, the scoping-review extension, which adapts the reporting items to the mapping purpose. Using the wrong reporting guideline is a reviewer-flagged error because it indicates the author has not fully grasped which type of review they conducted.
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The Cost of Choosing Wrong, in Both Directions
Both errors carry a real cost, and naming them precisely helps a researcher avoid them.
Choosing a scoping review when the question demanded a systematic review produces a map where the reader needed an answer. A candidate who scopes the literature on an intervention, when the examiner or the field wants to know whether the intervention works, has done legitimate work that does not address the actual question, and the review may be sent back to be redone as a systematic review with appraisal and synthesis. The scoping review cannot simply be relabeled, because it did not appraise the studies or synthesize their effects.
Choosing a systematic review when the field is too broad or immature produces a review that cannot be completed as designed. A researcher who commits to a focused, systematic review of a heterogeneous or emerging topic may find too few comparable studies to synthesize, or a body of evidence so varied that no meaningful pooled answer exists. Here, a scoping review should have come first to establish whether a systematic review was feasible. The precursor logic exists precisely to prevent this. Deciding correctly at the outset, against the indications above, is the only reliable way to avoid either outcome.
What Conducting a Scoping Review Actually Involves
Because the mapping purpose can make a scoping review sound less structured than a systematic review, it is worth setting out what the JBI methodology actually requires, since the rigor is comparable even though the aim differs. A scoping review conducted according to the current JBI standard moves through a defined sequence.
It begins with a title and a clearly stated objective and question, framed in PCC. It requires an a priori protocol, developed and ideally registered or published before the review begins, exactly as a systematic review does; the protocol specifies the objective, the eligibility criteria expressed through Population, Concept, and Context, the search strategy, and the approach to evidence selection and data extraction. The search is comprehensive and follows a three-step JBI approach: an initial limited search of two relevant databases to identify keywords and index terms, a full search across all included databases using those terms, and a search of the reference lists of included sources. Study selection is conducted in duplicate by independent reviewers against the eligibility criteria, with the process recorded in a PRISMA-ScR flow diagram, in the same way a systematic review documents selection.
The step that most distinguishes a scoping review is data charting rather than data extraction. Instead of extracting outcome data for synthesis, the reviewer charts descriptive information: the characteristics of each source, the concepts it addresses, the methods it used, and the elements relevant to the review question. The charting form is drafted a priori and refined iteratively as the review proceeds, one of the points Levac and colleagues emphasized. Finally, the results are collated, summarized, and reported, typically through descriptive tabulation accompanied by a narrative summary that maps the evidence and identifies gaps, and optionally through a stakeholder consultation exercise. A well-charted scoping review that documents its search and selection with this rigor is a substantial undertaking, and constructing a reproducible search for one is exacting work that our search strategy service supports for both review types.
Frequently Asked Questions
What is the main difference between a scoping review and a systematic review?
A systematic review answers a focused question, usually about effectiveness, by appraising and synthesizing the relevant studies. A scoping review maps the extent, range, and nature of the evidence on a broader topic without answering a single effectiveness question. The difference is one of purpose: a systematic review produces an answer, a scoping review produces a map of what evidence exists.
When should I do a scoping review instead of a systematic review?
Conduct a scoping review when your purpose is to identify the types of available evidence, clarify concepts or definitions, examine how research on a topic is conducted, identify knowledge gaps, or determine whether a systematic review is feasible. If your purpose is instead to answer a focused question about whether an intervention works, a systematic review is required.
Can I register a scoping review on PROSPERO?
No. PROSPERO accepts systematic reviews, rapid reviews, and umbrella reviews, but it does not accept scoping reviews. Scoping review protocols are registered on the Open Science Framework or Figshare, or published as a protocol in a journal such as JBI Evidence Synthesis or BMJ Open. Deciding your review type before attempting registration avoids a declined submission.
What is the difference between PCC and PICO?
PICO (Population, Intervention, Comparator, Outcome) frames a focused systematic review question of effectiveness, where a comparator and a defined outcome are essential. PCC (Population, Concept, Context) frames a scoping-review question, and per JBI, it does not require an explicit intervention, comparator, or outcome, because a scoping review maps evidence rather than comparing interventions or measuring effects.
Do I need to assess risk of bias in a scoping review?
Generally no. Per JBI guidance, critical appraisal of the risk of bias in included studies is not a required component of a scoping review, because the review maps evidence rather than drawing an effectiveness conclusion that would depend on study quality. A systematic review, by contrast, must appraise its included studies, because the trustworthiness of its answer depends on their internal validity.
Which reporting guideline applies to each review type?
A systematic review is reported according to PRISMA 2020, the 27-item checklist for systematic reviews. A scoping review is reported according to PRISMA-ScR, the scoping-review extension published by Tricco and colleagues in 2018, which adapts the reporting items to the mapping purpose. Using the wrong guideline is a common reviewer-flagged error.
Can a scoping review become a systematic review later?
A scoping review can serve as a precursor that establishes whether a systematic review is feasible, but it does not automatically convert into one. Because a scoping review generally does not appraise or synthesize its studies, a subsequent systematic review is a separate piece of work with its own focused question, critical appraisal, and synthesis. The scoping review usefully informs and scopes the later systematic review.
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Deciding Before You Commit
The researchers who avoid a wasted year are the ones who answer a single question honestly before they begin: Am I mapping the evidence, or answering a question about it? If mapping, a scoping review with a PCC question, registered on OSF, and reported to PRISMA-ScR. If answering, a systematic review with a PICO question, critical appraisal, PROSPERO registration, and PRISMA 2020 reporting. The two paths diverge at the very first step, and the cost of taking the wrong one is measured in months.
Bring us the question before you commit to a design, and a methodologist will tell you which review it calls for and set the registration and reporting path accordingly. Send your research question for a review-type assessment, and you will have an itemized quote within 2 to 4 business hours, with no obligation.
