Role of progressive urethral dilation and primary valve ablation in the long-term renal outcomes of small, preterm infants with posterior urethral valve
Jennifer M. Lovin, MD1, Charlotte Wu, MD2, Dattatraya Patil, MBBS, MPH1, Edwin A. Smith, MD1.
1Emory University School of Medicine, Atlanta, GA, USA, 2Johns Hopkins University School of Medicine, Baltimore, MD, USA.
BACKGROUND: Posterior urethral valves (PUV) is a congenital obstructive uropathy that commonly leads to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Early primary valve ablation (PVA) is preferred over primary vesicostomy as the gold standard surgical treatment. We previously described progressive urethral dilation (PUD) as an effective method of enhancing the likelihood of PVA in preterm and low birth weight infants, for whom PVA is otherwise unattainable due to small urethral caliber. Herein, we evaluate the long-term renal outcome of infants treated by PVA with PUD compared to those treated by PVA without PUD. A secondary objective is to determine, without the usual confounder of unequal primary surgical treatment methods in this cohort, whether renal outcomes differ for preterm, small birth weight infants. METHODS: We performed retrospective review of 69 neonates with PUV treated with primary valve ablation prior to 10 weeks of age. Boys either underwent PUD (serial upsizing of an initially smaller bore urethral catheter to an 8Fr catheter) or non-dilation (no-PUD; initially smaller bore catheter was maintained) before valve ablation. All had > 1 year of clinical and laboratory follow up. Demographics and clinical features were assessed initially using descriptive statistics with chi-square and t-test. Univariable and multivariable logistic regression were performed to assess the effect of PUD, preterm (<37 weeks), low birth weight (<2.5kg), reflux and other assumed predictors on the final outcomes of CKD Stage 3+ and ESRD. RESULTS: 31 of 69 patients underwent PUD. Mean clinical and lab follow up was 5.4 years (SD 3.4) and 5.6 years (SD 3.7) respectively, with no difference between groups compared. There was no significant difference in the distribution of final CKD stages (1-5) between those that underwent PUD vs no-PUD. Univariable analysis demonstrated no significant effect of PUD on final renal outcomes, with OR 1.4 (p=0.22) for CKD3+ and OR 0.9 (p=0.9) for ESRD. On univariable analysis, odds of CKD3+ was significantly (p< 0.05) higher in preterm infants, low birth weight infants, VUR-present, VUR-bilateral, and Cr nadir > 0.5 (Table 1). When adjusted for other variables, only Cr nadir >0.5 (OR 47.3, CI 6.9-324.4) remained an independent predictor of CKD 3+. A similar outcome was seen for ESRD (Table 1). CONCLUSIONS: We previously demonstrated that PUD is an effective means to achieve PVA in small neonates who might otherwise require vesicostomy. The data herein demonstrates no significant effect of PUD on long-term renal outcomes. Our results demonstrate complex roles of prematurity, low birth weight, and reflux on the final renal outcome, similar to that described in other studies. Only creatinine nadir served as a strong, independent predictor of outcomes in this unique cohort of newborns who were uniformly treated with PVA. 
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