Predicting progression to renal replacement therapy in children with posterior urethral valves: international validation of the secondary use of the posterior urethral valve risk of chronic kidney disease (PURK) score.

Abstract

Introduction: Congenital lower urinary tract obstruction due to posterior urethral valves (PUV) often results in chronic kidney disease (CKD) and renal replacement therapy (RRT). The Posterior Urethral Valve Risk of Chronic Kidney Disease (PURK) score, a validated prognostic tool, uses clinical variables at presentation to predict development of CKD stage 3 or higher. However, its role in predicting progression to RRT remains unexplored.

Objective: This study evaluates the utility of the PURK score for RRT risk stratification internationally, aiming to facilitate early counseling and management for affected families.

Study design: Patients with posterior urethral valves (PUV) presenting before age 1 were analyzed from internal and external databases (9 institutions), excluding early RRT events (<14 days). PURK scores were calculated. ROC curves assessed predictive accuracy and Kaplan-Meier survival analysis stratified risk groups. External validation involved data from eight international centers.

Results: Internal validation from 183 PUV patients at a single center, with a median follow-up of 8.1 years, was analyzed. This showed significant differences in PURK score distribution between patients who progressed to RRT (15.1 %) and those who did not. Kaplan-Meier curves identified low- (0-1, 0 %), intermediate- (2-3, 9.6 %), and high-risk groups (≥4, 37.5 %) for RRT progression. AUROC values demonstrated good predictive ability for 1-, 5-, and 10-year RRT events (0.798-0.839). External validation of 265 patients confirmed these findings, with excellent AUROC values for 1-, 5-, and 10-year RRT events (0.868-0.885) and consistent survival stratification.

Discussion: We identified clear risk groups for progression to RRT using survival analysis, with those with high PURK score being much more likely to progress to RRT compared to lower scores. Being able to prognosticate patients into different risk groups is important as it can guide frequency of follow up and early interventions including alpha-blockers, anticholinergics, or clean intermittent catheterization for children with higher risk profiles.

Conclusion: The PURK score is a reliable tool for early prediction and risk stratification of progression to RRT in PUV patients.