What is a systematic review?

A systematic review answers a focused research question by finding, selecting and appraising all the relevant studies with a predefined, reproducible method. Its protocol fixes the search, the inclusion criteria and the analysis in advance, and its report, usually following PRISMA, shows every step. It differs from a narrative review, which the author shapes freely.

A meta-analysis is a statistical combination of the results, often part of a systematic review.

Scoping reviews map a field more broadly, with less appraisal.