Evaluation of Urinary Tract Dilation Classification System for Prediction of Long-Term Outcomes in Isolated Antenatal Hydronephrosis: A Cohort Study.

PURPOSE: The aim of this study was to evaluate the performance of the new classification of urinary tract dilatation (UTD) to predict long-term clinical outcomes in infants with isolated antenatal hydronephrosis (ANH).

MATERIALS AND METHODS: Between 1989 and 2019, 447 infants diagnosed with isolated severe ANH and were prospectively followed. The main predictive variable for the analysis was the new UTD classification system. The events of interest were surgical interventions, urinary tract infections, chronic kidney disease stage II or higher, hypertension and proteinuria. The primary end-point was time until the occurrence of a composite event of renal injury, including proteinuria, hypertension and chronic kidney disease.

RESULTS: Among 447 infants with ANH included in the analysis, 255 (57%) had UTD P1, 93 (20.8%) UTD P2 and 99 (22.2%) UTD P3. Median followup time was 9 years (IQR 7-12 years). Of 447 patients included in the analysis, 11 (2.5%) had hypertension, 13 (2.9%) exhibited persistent mild proteinuria, 14 (3%) developed chronic kidney disease Stage 2 and 26 (5.8%) had the composite outcome of renal injury. By survival analysis, the UTD system predicted accurately all events of interest. According to the Kaplan-Meier survival analysis, the probability of renal injury at 20 years of age was estimated at about 0%, 14% and 56% for patients assigned to UTD P1, UTD P2 and UTD P3, respectively (p <0.001).

CONCLUSIONS: Our findings provide insights that the new UTD classification has a good performance for discriminating not only mid-term, but also long-term clinical outcomes, including renal injury.