Subgroup and effect-modification plan
Scientific rationale → subgroup definitions → interaction approach → precision and interpretation plan
Flow diagram
Steps
Scientific rationale
State why effect modification is plausible.
Prespecified subgroup definitions
Define subgroup variables, categories and timing before outcome review.
Interaction model and effect scale
Specify interaction contrast and scale rather than comparing within-subgroup significance.
Precision and multiplicity assessment
Assess sample support, uncertainty and confirmatory versus exploratory status.
Analysis and interpretation rules
Specify estimation, reporting and limits for small or sparse subgroups.
Tables and supporting information
Subgroup analysis plan
Use one row per prespecified subgroup and define handling of missing subgroup variables.
Interaction specification
Enter the interaction model and contrast for the chosen outcome and effect scale.
Effect-modification evidence
Record the scientific basis for each subgroup.