Introduction: Congenital anomalies of the kidney and urinary tract (CAKUT) represent a spectrum of structural malformations that arise during prenatal development and persist at birth. Pediatric kidney transplant recipients with CAKUT may face an increased susceptibility to urinary tract infections (UTIs) . In this study, we conducted a comparative analysis of graft survival, UTIs incidence, and renal function between pediatric kidney transplant recipients with and without CAKUT. Furthermore, we systematically evaluated potential risk factors associated with post-transplant UTIs development. 
Methods: We performed a retrospective cohort study of pediatric patients who underwent KTx between January 1, 2017 and December 31, 2022. Patients were stratified into two groups according to the underlying etiology of ESRD: CAKUT and non-CAKUT groups. Comparative analyses were conducted to evaluate between-group differences in graft survival rates, UTIs incidence, and renal allograft function to assess the impact of CAKUT on post-transplant outcomes.
Results: Our cohort comprised 320 pediatric kidney transplant recipients, with 61 patients (19%) having ESRD secondary to CAKUT and 259 patients (81%) with non-CAKUT-related ESRD. The mean follow-up duration was 4.31 years (range: 0.02-7.78years). In the CAKUT cohort, renal hypoplasia/dysplasia was the most common cause of ESRD, accounting for 67% (41/61) of cases while glomerular diseases were the leading cause of ESRD in the non-CAKUT group, comprising 58% (145/259) of cases. Graft survival analysis revealed comparable outcomes in both groups, with 3-year and 5-year survival rates of 98% in CAKUT patients compared to 97% and 96%, respectively, in non-CAKUT recipients. The incidence of acute rejection episodes did not differ significantly between groups (20% vs. 14%, P=0.39). Notably, CAKUT patients demonstrated a significantly higher post-transplant UTI incidence (28% vs. 15%, P=0.03). Multivariable logistic regression analysis identified female gender (OR = 2.0, P = 0.03) and vesicoureteral reflux (VUR) as the primary renal disease (OR = 4.0, P = 0.04) as significant risk factors for developing UTIs post-kidney transplantation. In contrast, neither pretransplant hypospadias (OR=4.9, P=0.3) nor Denys-Drash syndrome (OR=2.0，P=0.6) showed significant associations with UTI risk.
Conclusion: This comparative analysis demonstrates comparable graft survival and rejection rates between CAKUT and non-CAKUT pediatric transplant recipients. However, the significantly higher UTIs incidence among CAKUT patients. Female patients and VUR are key risk factors for developing UTIs after kidney transplantation, while pretransplant hypospadias and Denys-Drash syndrome did not show significant associations. These findings suggest that pre-transplant urological evaluation and targeted prophylactic strategies may be warranted for CAKUT patients, especially those with concomitant VUR.