“…This is a registry study, with limited set of variables, so several kidney transplantation-related factors that may have contributed to a country's ability to transplant pediatric patients are unavailable. Previous studies showed that differences in kidney transplantation policies, such as recommendations regarding living or deceased donation, the maximum accepted donor age, cold ischemia time, minimum accepted recipient age, and HLA-matching, may also play a role in explaining country differences in access to transplantation, 4,11 along with various cultural, local, and logistic factors. 17 All these factors may partly explain the variation in access to kidney transplantation, and their absence in our analyses may have led to some degree of residual confounding.…”