A clinical predictive model of renal injury in children with isolated antenatal hydronephrosis

BACKGROUND: Antenatal hydronephrosis (ANH) affects ∼1–5% of pregnancies. The aim of this study was to develop a clinical prediction model of renal injury in a large cohort of infants with isolated ANH. METHODS: This is a longitudinal cohort study of 447 infants with ANH admitted since birth between 1989 and 2015 at a tertiary care center. The primary endpoint was time until the occurrence of a composite event of renal injury, which includes proteinuria, hypertension and chronic kidney disease (CKD). A predictive model was developed using a Cox proportional hazards model and evaluated by C-statistics. RESULTS: Renal pelvic dilatation (RPD) was classified into two groups [Grades 1–2 (n = 255) versus Grades 3–4 (n = 192)]. The median follow-up time was 6.4 years (interquartile range 2.8–12.5). Thirteen patients (2.9%) developed proteinuria, 6 (1.3%) hypertension and 14 (3.1%) CKD Stage 2. All events occurred in patients with RPD Grades 3–4. After adjustment, three covariables remained as predictors of the composite event: creatinine {hazard ratio [HR] 1.27, [95% confidence interval (CI) 1.05–1.56]}, renal parenchyma thickness at birth [HR 0.78(95% CI 0.625–0.991)] and recurrent urinary tract infections [HR 4.52 (95% CI 1.49–13.6)]. The probability of renal injury at 15 years of age was estimated as 0, 15 and 24% for patients assigned to the low-risk, medium-risk and high-risk groups, respectively (P < 0.001). CONCLUSION: Our findings indicate an uneventful clinical course for patients with Society for Fetal Urology (SFU) Grades 1–2 ANH. Conversely, for infants with SFU Grades 3–4 ANH, our prediction model enabled the identification of a subgroup of patients with increased risk of renal injury over time.