New endometrial immune cell-based score (EI-score) for the prediction of implantation success for patients undergoing IVF/ICSI

Problem: Limited evidence revealed whether endometrial immunological factors contribute to implantation success in the first-attempted in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients. Method: The retrospective study was conducted among 139 eligible couples in the derivation cohort and 29 couples in the validation cohort. The expression of endometrial immune cell markers, including CD56 for natural killer cell, CD68 for pan-macrophage, CD163 for M2 macrophage, FOXP3 for regulatory T cell, CD1a for immature dendritic cell, CD83 for mature dendritic cell, CD8 for cytotoxic T cell and CD57 for mature NK and T cells were examined. Results: The profiles of endometrial immune cells showed significant difference between the pregnant and implantation failure group in the derivation cohort. Multivariate logistic regression analysis showed that the percentage of CD68(+) pan-macrophage and CD163(+) M2-macrophage, as well as the transfer strategy are associated with implantation outcomes (P < 0.001, P = 0.029, P = 0.004, respectively). The EI-score was constructed by a nomogram and validated by a clinical decision curve based on CD68(+) pan-macrophage, CD163(+) M2-macrophage, and the transfer strategy. The performance of the EI-score in the deviation cohort showed a cindex of 0.82 (95% CI 0.74-0.89), and the accuracy rate reached 79.3% in the validation cohort. Conclusions: The endometrial immunological profiles in the mid-secretory phase is associated with implantation outcome in the first IVF/ICSI patients. EI-Score could help clinicians calculate the probability of implantation success via nomogram. Optimal decision point is determined by decision curve analysis and clinical impact curve, to aid in clinical decisions.