ObjectiveTo evaluate the effectiveness of hormone replacement therapy (HRT) combined with Kuntai capsule in the treatment of diminished ovarian reserve (DOR) in the clinical practice based on real world data (RWD). MethodsEmploying a target trial emulation framework, this study utilized electronic medical record data from the Tianjin Regional Healthcare Database. The outcome measures were the changes from baseline in follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) levels within 3 months of treatment. Inverse probability weighting was used to balance baseline confounders, and the average treatment effect (ATE) was estimated based on weighted linear models. The primary analysis included patients with complete FSH data, and multiple sensitivity analyses were conducted to verify the robustness of the results. ResultsA total of 239 patients with DOR who had at least one sex hormone outcome were included. Among them, 198, 142, and 223 patients had complete data for FSH, LH, and E2, respectively. In the primary analysis population (n=198), 131 patients were in the Western medicine group (HRT alone) and 67 were in the combination group (HRT plus Kuntai capsule). Compared to the Western medicine group, the combination group showed a significantly greater reduction in FSH levels (ATE=?5.92IU/L, 95%CI ?10.73 to ?1.12). In the population with complete E2 data, the combination group demonstrated a significantly greater increase in E2 levels (ATE=61.03pg/mL, 95%CI 33.16 to 88.91). For LH, the difference was not statistically significant between two groups. ConclusionIn real world clinical practice, HRT combined with Kuntai capsule is superior to HRT alone in improving FSH and E2 levels in patients with DOR. These findings are consistent with previous clinical evidence and suggest that the target trial emulation framework holds significant methodological value for evaluating the efficacy of integrated Chinese and Western medicine therapies.