Interpretation of subgroup analyses in systematic reviews: A tutorial

Authors of systematic reviews may perform subgroup analyses to investigate how treatment effect varies across different subgroups of patients or trials. Previous research has shown that Cochrane review authors do not sufficiently report their interpretation of subgroup analyses. Consequently, we developed a tutorial with the aim of improving the interpretation of subgroup analyses in reviews. We explain the importance of interpreting subgroup analyses, and demonstrate how to interpret subgroup analyses using theoretical examples and a real-life subgroup analysis with clinical context. Finally, we provide recommendations for the interpretation of subgroup analyses in systematic reviews.