Introduction to Trial‐Level Subgroup Analysis: A Tutorial

This tutorial introduces the concept of trial-level subgroup analysis in meta-analysis. We describe the rationale for conducting subgroup analyses, distinguish trial-level from participant-level characteristics, outline how to properly interpret effects within subgroups, and illustrate how to perform a trial-level subgroup analysis, including formal statistical testing for differences between subgroups. A complementary micro-learning module is provided to support additional learning of these concepts.