Estimating risk difference from relative association measures in meta-analysis can infrequently pose interpretational challenges

OBJECTIVE: Risk difference (RD) is often estimated from relative association measures generated by meta-analysis and a particular group's baseline risk. We describe a problematic situation in using this approach. STUDY DESIGN AND SETTING: We encountered a meta-analysis in which a confidence interval (CI) of relative risk (RR) overlapped 1.0; the point estimate favored treatment A, but when we used RR and median baseline risk to calculate a CI …