A systematic review searches exhaustively, with a predefined method, for all the studies that answer a specific question, then appraises and summarises them. When those studies are similar enough, the meta-analysis pools their data to calculate an overall effect with more participants than any single study has.
That is why they usually sit at the top of the evidence hierarchy, above individual trials, observational studies and, far above, case series, expert opinion and animal studies.
Their quality depends on what they combine: a meta-analysis of small, biased studies produces a precise but wrong conclusion. Heterogeneity (how different the studies were) and whether publication bias was checked also need to be looked at.
For most research peptides there are no meta-analyses in humans, simply because there are not enough clinical trials. That absence is information too.
Related terms
Learn it in depth at the Peptide University
- Hierarchy of evidence and development phases · Module 13
Definition for educational and scientific purposes. It is not medical advice or a recommendation for use. NeoPeptidos products are sold labelled for research use only (RUO).