Target trial emulation (TTE) has gradually developed into a mainstream framework for causal inference in pharmacoepidemiological research. By emulating the design elements of randomized controlled trials (RCTs), TTE significantly enhances the quality of observational studies. Based on the Guide on Methodological Standards in Pharmacoepidemiology (2nd edition), this article interprets the fundamental principles of commonly used TTE designs. It focuses on introducing the basic principles, applicable scenarios, and implementation steps of the three commonly used TTE designs: the active comparator new-user (ACNU) design, sequential trials, and the clone-censor-weight (CCW) approach. Typical case studies are presented to illustrate the specific applications of each design in pharmacoepidemiology. Finally, this article compares the fundamental characteristics of these three designs and offers guidance on selecting an appropriate design type based on research objectives.

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