Development and international validation of a novel multivariate prognostic tool: posterior urethral valve risk of chronic kidney disease (PURK) score

Abstract

Background: Chronic kidney disease (CKD) affects up to 40% of children diagnosed with posterior urethral valves (PUV). This study aimed to develop and validate a risk stratification tool based on clinical variables available at presentation to predict CKD progression in children with PUV.

Methods: This multicenter retrospective cohort study included data from 283 children diagnosed with PUV before 12 months of age, treated at seven pediatric centers across four countries. Patients were followed for a minimum of one year to assess CKD progression. Using patients from the largest institutional cohort, clinical variables at initial presentation, including baseline creatinine, high-grade vesicoureteral reflux (VUR), failure to thrive (FTT), and kidney dysplasia, were identified through backward logistic regression analysis and used to develop the Posterior Urethral Valve Risk of Kidney disease (PURK) score, which was then externally validated at six centers.

Results: The PURK score identified baseline creatinine > 150 µmol/L, high-grade VUR, FTT, and kidney dysplasia as significant predictors of CKD stage ≥ 3. In the development cohort, the score achieved excellent predictive accuracy, with an area under the receiver operating characteristic curve (AUROC) of 0.907 at 1 year and 0.873 at 5 years. External validation across six additional institutions confirmed high predictive value, with AUROCs of 0.849 and 0.877 at 1 and 5 years, respectively.

Conclusions: The PURK score is a reliable tool for predicting CKD progression in children with PUV, using accessible clinical data. Its implementation may support individualized care, improve family counseling, and allow comparison of similar risk-group patients for both clinicians and researchers.

Keywords: CKD; Chronic kidney disease; PURK score; PUV; Posterior urethral valve; Prediction model.