Subgroup analysis methods for time-to-event outcomes in heterogeneous randomized controlled trials

Not all methods are suited for all heterogeneity investigations. We recommend employing interaction test-based methods to detect heterogeneity and identify predictive variables, and leveraging multivariate CATE estimation-based approaches for subgroup identification. Moreover, we recommend adopting a two-step strategy consisting of (i) establishing the existence of heterogeneity and finding responsible covariates using interpretable methods and (ii) looking for subgroups using more complex methods.