Predicting childhood chronic kidney disease severity in infants with posterior urethral valve: a critical analysis of creatinine values in the first year of life.

BACKGROUND: Posterior urethral valve (PUV) is a leading cause of chronic kidney failure in children. Studies have shown that a creatinine nadir above historical cutoff values of 0.8 or 1.0 mg/dL correlates with worse kidney outcomes. The ability to use nadir creatinine more discriminately as a test of kidney outcomes is otherwise limited.

METHODS: We performed a retrospective review of 102 infants treated with primary valve ablation prior to 1 year of age. Patient factors including creatinine at presentation (Cr-P), nadir within 6 weeks after ablation (Cr-6 W), and nadir within 1 year after ablation (Cr-1Y) were assessed as predictors of final chronic kidney disease (CKD) severity. An optimal threshold for four CKD levels was defined in incremental fashion using binary outcome with receiver operating characteristic (ROC). Multivariable logistic regression models compared Cr-P, Cr-6 W, and Cr-1Y while adjusting for patient factors.

RESULTS: Boys were ablated at mean age of 36.3 days and followed for 6.6 years (± 3.7). When compared to other demographics, only creatinine remained independently predictive of CKD outcomes on multivariable analysis. ROC analysis demonstrated excellent diagnostic accuracy for Cr-6 W and Cr-1Y (p < 0.001) and acceptable accuracy for Cr-P (p < 0.005). Using the Cr-6 W and Cr-1Y models, high sensitivity and specificity creatinine nadir cutoffs were determined to predict each CKD outcome.

CONCLUSIONS: The severity of childhood CKD can be predicted with high accuracy using the creatinine nadir within 6 weeks of ablation. The cutoff values described can be incorporated into a clinical setting for patient counseling and individual risk stratification.