Examples
Worked examples
- Is an instance
A Cochrane systematic review of trials of statins for primary prevention, with PROSPERO registration and PRISMA flow diagram
Counter-examples
Looks similar, but isn't
- Not an instance
A narrative summary of selected papers is not a systematic review even if labelled 'systematic'
Editorial commentary
A systematic review follows a pre-specified, typically registered protocol to identify, appraise, and synthesise all evidence bearing on a focused research question, using explicit and reproducible methods for searching, screening, data extraction, and quality assessment. The defining features are the protocol (usually PRISMA-P structured and registered in PROSPERO before the review starts) and the reproducibility of the search and screening process — a reader should be able to follow the same steps and reach a comparable set of included studies.
How this differs from a meta-analysis, scoping review, and living review
A systematic review need not contain a meta-analysis — per the Cochrane Handbook, statistical pooling is an optional step within a systematic review, not a defining requirement of one; many systematic reviews conclude that the included studies are too heterogeneous to pool. It differs from a scoping review in asking a focused question (“does X work?”) rather than mapping the breadth of a topic (“what evidence exists on X?”), and in formally appraising study quality, which scoping reviews typically do not. A living systematic review is a systematic review maintained under continuous update rather than published once as a fixed snapshot — the review type is the same, only the maintenance model differs.
Example
A Cochrane systematic review of trials of a drug class for a defined indication, registered in PROSPERO before screening began and reported per the PRISMA 2020 checklist, including a flow diagram documenting records identified, screened, and included.
Reporting standard
PRISMA 2020 (Page et al., BMJ 2021) is the current reporting standard for systematic reviews generally; PRISMA-ScR is the separate extension for scoping reviews (see below). A narrative literature summary that has not followed a registered, reproducible protocol is not a systematic review, regardless of how it is labelled.
Also known as
SR · Systematic literature review
Machine-readable encodings
Use in your systems
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