Direct comparison
Systematic review vs meta-analysis — the difference
Systematic review vs meta-analysis explained: the difference is a protocol-driven synthesis of all eligible studies versus the statistical method that pools their results.
Side-by-side comparison
| Dimension | Systematic review | Meta-analysis |
|---|---|---|
| What it is | A structured synthesis of all eligible studies on a defined question. | A statistical method that combines results across studies. |
| Primary aim | Identify, appraise and summarise the evidence comprehensively. | Produce a single pooled quantitative estimate of effect. |
| Nature | A complete review methodology and process. | A statistical analysis technique, often one step within a review. |
| Output | A narrative and tabular synthesis, with or without pooled statistics. | A combined effect size, confidence interval and often a forest plot. |
| Requires numerical data? | No — can synthesise qualitative or heterogeneous evidence. | Yes — needs comparable quantitative results to pool. |
| Protocol and registration | Pre-specified protocol, ideally registered (e.g. PROSPERO). | Conducted under the host review’s protocol. |
| Guiding standards | PRISMA reporting; Cochrane methods. | PRISMA plus statistical pooling and heterogeneity assessment. |
| Can exist without the other? | Yes — many systematic reviews contain no meta-analysis. | Ideally embedded in a systematic review to avoid bias. |
| Key risk | Incomplete searching or biased study selection. | Pooling heterogeneous studies that should not be combined. |
Common questions
FAQ
Is a meta-analysis the same as a systematic review?+
No. A systematic review is the overall method of finding, appraising and synthesising studies, while a meta-analysis is the statistical step of pooling their numerical results. A systematic review can be done without a meta-analysis, and a meta-analysis is most trustworthy when carried out within a systematic review.
Can a systematic review have no meta-analysis?+
Yes. When the included studies are too few, too different in design, or report outcomes too dissimilar to combine, a systematic review presents a narrative synthesis instead of pooling the data. Forcing a meta-analysis on heterogeneous studies can produce a misleading combined estimate, so reviewers often decline to pool.
What standards govern systematic reviews and meta-analyses?+
PRISMA sets the reporting standard for both, specifying how the search, selection and synthesis are documented. Cochrane provides detailed methodological guidance, especially in health research, and registries such as PROSPERO record protocols in advance to reduce bias and selective reporting.
