Conducting proportional meta-analysis in different types of systematic reviews: a guide for synthesisers of evidence

Barker, Timothy Hugh; Migliavaca, Celina Borges; Stein, Cinara; Colpani, Verônica; Falavigna, Maicon; Aromataris, Edoardo; Munn, Zachary

BACKGROUND: Single group data present unique challenges for synthesises of evidence. Proportional meta-analysis is becoming an increasingly common technique employed for the synthesis of single group data. Proportional meta-analysis shares many similarities with the conduct and reporting of comparative, or pairwise, meta-analysis. While robust and comprehensive methods exist detailing how researchers can conduct a meta-analysis that compares two (or more) groups against a common intervention, there is a scarcity of methodological guidance available to assist synthesisers of evidence in the conduct, interpretation, and importance of proportional meta-analysis in systematic reviews. MAIN BODY: This paper presents an overview targeted to synthesisers of evidence and systematic review authors that details the methods, importance, and interpretation of a proportional meta-analysis. We provide worked examples of how proportional meta-analyses have been conducted in research syntheses previously and consider the methods, statistical considerations, and presentation of this technique. CONCLUSION: This overview is designed to serve as practical guidance for synthesisers of evidence in the conduct of proportional meta-analyses.