Post-transplant kidney function decline in children with posterior urethral valves versus non-urologic etiologies: roles of catheterization, infection, and rejection.

BACKGROUND: Posterior urethral valves (PUV) is a leading cause of childhood kidney failure requiring kidney transplantation (KT). Although graft survival in transplant patients with PUV has been reported to be similar to non-urologic etiologies of kidney failure, differences in long-term graft function and clinically meaningful kidney outcomes remain incompletely characterized. We compared post-KT progression to chronic kidney disease (CKD) in children transplanted for PUV versus non-urological conditions, exploring factors associated with faster decline.

METHODS: A retrospective cohort study of pediatric KT recipients transplanted between 2000 and 2024 was conducted. Thirty-one patients with PUV were matched 1:1 by age at KT to males with non-urologic causes. Kidney function was assessed using estimated glomerular filtration rate (eGFR) at fixed time intervals. Time-to-event (TTE) analyses were performed for the development of CKD stage ≥ 3. Multivariable Cox proportional hazards regression evaluated factors associated with progression to CKD stage ≥ 3.

RESULTS: Baseline demographic and KT characteristics, including rejection rates, were similar across groups. Patients with PUV had lower eGFR than controls at 1-10 years after KT. Post-transplant urinary tract infections (UTI) were significantly more common in patients with PUV (68% vs. 3%, p < 0.01). TTE analysis demonstrated earlier progression to CKD stage ≥ 3 among patients with PUV. In multivariable Cox regression, rejection was independently associated with progression to CKD stage ≥ 3 after adjusting for infections. Four graft losses occurred in the PUV cohort and none in the control cohort. Exclusion of graft losses did not alter TTE results.

CONCLUSIONS: Despite similar KT characteristics and rejection rates, children transplanted for PUV experience more infections and earlier deterioration of graft function and progression to CKD compared with children transplanted for non-urologic causes. These findings suggest the need for long-term, close monitoring and the proactive use of strategies to optimize bladder function in PUV KT recipients.