What the term does not establish
Keep the category boundary visible
- It is not simply an article that cites many studies.
- It is not automatically a meta-analysis.
- The review label does not guarantee high-certainty evidence.
Safety and research
Systematic review
SR
Definition
A systematic review uses predefined, transparent methods to identify, select, appraise, and synthesise studies that answer a focused question.
Aliases and abbreviations
SR · systematic evidence review · evidence synthesis
Editorial record
Published: August 25, 2026 · Reviewed: August 25, 2026
Expanded definition
Systematic review
A review normally specifies the question, eligibility criteria, search strategy, study-selection process, data extraction, risk-of-bias methods, and synthesis plan before drawing conclusions.
Systematic does not mean flawless or complete. Searches can miss studies, eligibility decisions can introduce bias, included studies may be weak, and outcomes or protocols may be too heterogeneous to combine.
A systematic review may contain a meta-analysis, but it does not have to. Narrative synthesis may be more appropriate when statistical pooling would obscure important differences.
Why the distinction matters
Precision changes interpretation
Transparent methods make the evidence base traceable, while critical appraisal prevents the review's conclusion from being treated as stronger than its included studies.
Main guide
Scientific studies library
Individual study summaries and evidence resources across VNS, safety, HRV, sleep, and mechanism research.
Browse evidenceRelated terms
Safety and research
Meta-analysis
Open definitionSafety and research
Randomized controlled trial
Open definitionMeasurement and interpretation
Certainty of evidence
Open definitionSafety and research
Adverse event
Open definitionMeasurement and interpretation
Target engagement
Open definitionSafety and research
Tolerability
Open definitionEditorial scope
A definition is an entry point, not a product claim
This glossary entry supports general education. It does not diagnose, recommend treatment, or transfer findings from one VNS method, protocol, or device to another.