In distinguishing between a systematic review and a meta-analysis, which statement is correct?

• A. A meta-analysis is the formal quantitative synthesis across studies.
• B. A systematic review is the formal quantitative synthesis across studies.
• C. They are unrelated processes.
• D. A meta-analysis always includes a narrative summary.

Answer: (A)

Meta-analysis is the formal quantitative synthesis across studies. It uses statistical methods to combine the results of multiple studies to produce a single pooled estimate of effect, often with measures of precision and heterogeneity. A systematic review, on the other hand, is the structured process of searching for, appraising, and summarizing all relevant evidence on a topic; it may include a narrative synthesis and, if data permit, a meta-analysis, but the review itself is not defined by quantitative pooling. Therefore the statement that a meta-analysis is the formal quantitative synthesis across studies is the best description. The other options mischaracterize the relationship (systematic reviews are not inherently quantitative syntheses, and they are not unrelated processes), and a meta-analysis does not always include a narrative summary.