Why the choice matters
The word review covers methods with very different aims, and choosing the wrong one wastes effort and gives an answer to a different question from the one intended. A narrative review chosen because it seems quick may be rejected by a journal that wants a systematic review. A systematic review chosen for a broad exploratory topic may become unmanageable. A scoping review used to claim that an intervention works will be criticized, because it does not assess the quality of evidence or estimate effects. And a review that uses the name systematic without the methods invites criticism that it is neither.
The type of review also affects the standards that apply: the reporting guideline, the registration options, the appraisal tools and the way conclusions can be worded. Choosing it deliberately, at the start, is part of a sound protocol. The comparison below sets out the main differences, and each type has its own page for the details.
The main types at a glance
| Type | Main purpose | Appraises quality? | Pools results? | Reporting guidance |
|---|---|---|---|---|
| Systematic review | Answer a focused question about effects, accuracy or association | Yes | Where suitable | PRISMA 2020 |
| Scoping review | Map the extent and nature of evidence; clarify concepts | Usually not | No | PRISMA-ScR |
| Rapid review | Provide evidence for a time-limited decision | Often limited | Sometimes | PRISMA, with shortcuts stated |
| Umbrella review | Synthesize existing systematic reviews | Yes, of the reviews | Rarely | PRIOR |
| Integrative review | Combine studies of different designs on a topic | Varies | No | PRISMA as a guide |
| Narrative review | General overview or discussion of a field | Not systematically | No | SANRA as a quality guide |
| Qualitative evidence synthesis | Understand experiences, meanings and processes | Yes, with qualitative tools | Not statistically | ENTREQ, PRISMA |
| Mixed-methods review | Combine quantitative and qualitative evidence | Yes | Where suitable | PRISMA and others |
| Realist review | Explain how and why programs work in context | Relevance and rigor | No | RAMESES |
| Living systematic review | Keep a review current as evidence accumulates | Yes | Where suitable | PRISMA, with update rules |
A way to decide
Write the question you need answered
In a sentence. Is it about whether something works, how accurate it is or what is associated with what? Or is it about what has been studied, how a concept is used, or how people experience something?
Decide how the answer will be used
For a guideline, a policy or a clinical decision, a systematic review is usually expected. For planning research, a scoping review may be enough.
Check what evidence exists
A scan of the literature shows how many primary studies and existing reviews there are. If good reviews already exist, an umbrella review or an update may be better than a new review.
Consider time and resources
A full systematic review takes substantial time. If a decision cannot wait, a rapid review with stated shortcuts may be the compromise.
Check the requirements of the audience
Journals, funders and degree programs may have preferences or rules about the type of review and the reporting guideline.
Frequently confused pairs
- Systematic review and meta-analysis
- A systematic review is the process of finding and appraising studies, and a meta-analysis is the statistical combination of their results. Many systematic reviews contain one, and many do not. See meta-analysis versus systematic review.
- Systematic review and scoping review
- A systematic review answers a focused question and appraises study quality. A scoping review maps a broad topic and usually does not.
- Systematic review and narrative review
- A narrative review is not systematic: it does not follow a protocol, a comprehensive search or explicit criteria, so it is more open to selection bias.
- Systematic review and umbrella review
- An umbrella review summarizes systematic reviews and not primary studies, and it must deal with overlap among them.
- Integrative review and systematic review
- An integrative review accepts diverse designs, including theoretical and empirical work, and is common in nursing. It is often less strict in methods than a systematic review.
- Rapid review and systematic review
- A rapid review is a systematic review with deliberate simplifications to meet a deadline. It should state them and their risk.
Strengths and weaknesses of each type
- Systematic review
- Strongest for answering focused questions, with the greatest transparency and the least selection bias. Demanding in time and skills, and limited to questions that studies can answer.
- Scoping review
- Strong for mapping a broad or messy field and for exposing gaps and definitions. Weak for judging effects, since quality is usually not appraised.
- Rapid review
- Strong for meeting a deadline. Weaker in completeness and certainty, depending on the shortcuts, which must be disclosed.
- Umbrella review
- Strong for a broad overview when many reviews exist, and for explaining why they conflict. Limited by the quality and currency of the reviews and by overlap.
- Integrative review
- Strong for combining diverse evidence, including theory, on a practice or concept. Methods vary, and rigor depends on the team.
- Narrative review
- Strong for expert interpretation and context. Weak on reproducibility and exposed to selection bias.
- Qualitative evidence synthesis
- Strong for understanding experience and mechanism, and for explaining why interventions work for some. Does not estimate effects.
- Mixed-methods review
- Strong when a question needs both effects and experience. Demands both skill sets and a clear approach to integration.
- Realist review
- Strong for explaining how context shapes the working of complex programs. Interpretive, and hard to standardize.
- Living systematic review
- Strong for fast-moving evidence where decisions need the latest findings. Needs sustained resources and clear rules for updating.
Time, team and skills
The effort needed differs greatly. A scoping or rapid review can be done by a small team in months, while a full systematic review with meta-analysis usually takes longer and needs several people: content experts, an information specialist for the search, reviewers for screening and extraction, and a statistician. An umbrella review needs the appraisal skills for reviews and care over overlap. A qualitative synthesis needs experience in qualitative methods, and a realist review needs theory-building skill. A living review demands a continuing commitment, not a single project. Planning the team and the time at the start, honestly, prevents a review being started that cannot be finished to the standard its type requires. The stages are described on the process page.
Differences by field
Conventions vary across disciplines. In health care, the Cochrane model of the systematic review is the standard, with registration in PROSPERO, risk-of-bias tools and GRADE. In nursing and allied health, integrative and scoping reviews are common, and the Joanna Briggs Institute provides methodology for several types. In education and social policy, the Campbell approach and realist methods are used, with an emphasis on context and mechanism. In management and business, systematic reviews often include a broad range of designs and use thematic synthesis. In environmental science, systematic maps and the guidance of the Collaboration for Environmental Evidence apply. The names overlap, and the safest way to choose is by the aim of the review, with the field's conventions as a guide. See research areas.
Worked examples of choosing
- "Does a school-based exercise program reduce depression in adolescents?"
- A focused question about effect: a systematic review, with a meta-analysis if the trials are comparable. Register the protocol, appraise risk of bias and rate certainty.
- "What has been done on digital tools for self-management of chronic illness?"
- A broad, exploratory topic with many designs: a scoping review, framed by population, concept and context, with charting and a map of gaps.
- "The health ministry needs a summary in eight weeks of the evidence on a new screening test."
- A time-limited decision: a rapid review, with the shortcuts agreed with the ministry and stated, and a note of what a full review might add.
- "Several reviews disagree about whether vitamin supplements prevent a range of conditions."
- Conflicting reviews on a broad question: an umbrella review, with an overlap analysis and an appraisal of the reviews to explain the conflict.
- "Why does a community program work in some towns and not others?"
- A question about context and mechanism: a realist review, possibly combined with a qualitative synthesis.
- "What do patients say about living with a rare condition?"
- A question about experience: a qualitative evidence synthesis, with appraisal using a qualitative tool and confidence rated with an approach such as GRADE-CERQual.
These cases are illustrative. In each, the design follows from the question and the use of the answer, which is the method recommended throughout this guide.
Common mistakes in choosing
- Calling a review systematic when it has no protocol, no documented search or no explicit criteria.
- Choosing a scoping review to avoid the work of appraisal while drawing conclusions about effectiveness.
- Choosing a narrative review because it is quick and expecting it to meet a journal's standard for a review.
- Planning a meta-analysis before knowing whether the studies can be combined.
- Starting a systematic review without checking whether a recent, good one already exists.
- Using the rapid label to describe an incomplete review without stating what was shortened.
Combining designs
The categories are not exclusive, and projects often combine them. A scoping review can be the first stage of a systematic review, establishing the concepts and the available evidence before the question is narrowed. A systematic review can be converted into a living review by adding a plan for updating. A mixed-methods review combines a systematic review of effects with a synthesis of qualitative evidence on implementation. An umbrella review can be supplemented with a search for primary studies published after the latest review. The point is to be clear about each component, to follow the standards of each, and to describe the combination openly in the protocol and the report.
Support
Choosing the design is the first part of the scoping stage of a project, described on the process page, and the systematic review and protocol services cover the work that follows.
Get a quoteDescribe your question and we will suggest a design.
Frequently asked questions
Which type of review do journals prefer?
It depends on the journal and the question. Many journals prefer systematic reviews for questions of effect, and some publish scoping, rapid or narrative reviews. Check the instructions for authors.
Is a scoping review easier than a systematic review?
Not necessarily. The breadth of the question can make it large, and it has methodological requirements of its own. It answers a different kind of question.
Can I do a meta-analysis without a systematic review?
A meta-analysis should normally be based on a systematic search and selection, otherwise the pooled estimate describes only the studies that happened to be found.
When is a narrative review acceptable?
For a general overview or discussion when a systematic answer is not needed, with the limits acknowledged. It should not be presented as systematic.
What if I am not sure which type I need?
Describe your question and the use of the answer. The scoping stage of a project is where the design is chosen, and it is often possible to decide after a short scan of the literature.
Can I change the type of review during the work?
It is possible, but changes should be recorded and reported, and the standards of the new type must be met. It is better to decide at the start.
References
- Grant MJ, Booth A. A typology of reviews: an analysis of 14 review types and associated methodologies. Health Info Libr J. 2009;26(2):91-108.
- 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;18:143.
- Sutton A, Clowes M, Preston L, Booth A. Meeting the review family: exploring review types and associated information retrieval requirements. Health Info Libr J. 2019;36(3):202-222.
- Whittemore R, Knafl K. The integrative review: updated methodology. J Adv Nurs. 2005;52(5):546-553.
- Higgins JPT, Thomas J, Chandler J, et al., editors. Cochrane Handbook for Systematic Reviews of Interventions. Cochrane; current version available at training.cochrane.org/handbook.
- Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021;372:n71. doi:10.1136/bmj.n71
- Tricco AC, Lillie E, Zarin W, et al. PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Ann Intern Med. 2018;169(7):467-473.
- Gates M, Gates A, Pieper D, et al. Reporting guideline for overviews of reviews of healthcare interventions: development of the PRIOR statement. BMJ. 2022;378:e070849.