An operational target trial emulation framework for causal inference using electronic health record data

Target trial emulation (TTE) enables causal inference from electronic health record (EHR) data when randomized clinical trials are infeasible, but its validity depends on whether EHR data can support the required trial design components. This review presents an operational framework that distinguishes trial specification from its realization in EHR data and clarifies how healthcare-driven data generation constrains identifiability and when EHR-based TTE can or cannot yield interpretable causal estimates.