Dear researchers, I am writing to request clarification regarding the minimum number of papers needed for a systematic review and meta-analysis. Could you please offer some guidance on this issue?
The systematic review on a specific domain can be performed (protocol and search) even if there is no article in the end that are found (meaning that there is no available evidence on the topic under interest).
For meta-analysis, if research studies results can be pooled together for meta-analysis you can theoretically report meta-analysis in n>=2 studies. however, the more studies you get the more analyses you can do.
In many paper in my research area (veterinary science), meta-analysis are conducted when at least 5 papers are available. You can see this paper from Yemisi Takwoingi et al on that topic from a statistical standpoint.
My 2 cents
Takwoingi Y, Guo B, Riley RD, Deeks JJ. Performance of methods for meta-analysis of diagnostic test accuracy with few studies or sparse data. Stat Methods Med Res. 2017 Aug;26(4):1896-1911. doi: 10.1177/0962280215592269. Epub 2015 Jun 26. PMID: 26116616; PMCID: PMC5564999.