Are early prognostic indicators reliable in posterior urethral valves management?

Abstract

Objective: To identify indicators that predict outcome in posterior urethral obstruction management in a resource-constrained environment with emphasis on the importance of early indicators. Subjects and methods: A retrospective review of all children who were managed for posterior urethral obstruction from 2002 to 2012 was done. Variables studied were: age at diagnosis (AgD) and of ablation, creatinine at diagnosis (CrD), nadir creatinine (CrN), vesicoureteric reflux (VUR), urinary diversion, and urodynamic study (UDS) findings. These were evaluated against two groups of patients—those with end stage renal disease (ESRD)-Group A and those with normal renal function-Group B. Significant variables were entered into a multivariate logistic regression to identify the independent prognostic factors that determine progression to ESRD. The independent factors were further analyzed with the receiver operating characteristics (ROC) to identify cutoff levels. The data is expressed as mean ± SD and median (IQR). A p-value of 0.05 was regarded as significant. Results: Sixty patients had adequate documents for evaluation. ESRD was identified in 30% of the cases. The AgD was 2.5 weeks (1–18 weeks). CrD, CrN, abnormal UDS, and VUR were significant prognostic indicators of ESRD (p = 0.0001), with CrN and CrD being independent factors on regression analysis. CrD value of ≥102 μmol/L had sensitivity of 94.4% and specificity of 68.3%, with a PPV of 56.7% (CI: 37.4–74.5) and a NPV of 96.6% (CI: 82.2–99.9). CrN of ≥89 μmol/L had sensitivity of 27.8% and a specificity of 95.1% with a PPV of 71.4% (CI: 29%–96.3%) and NPV of 75% (CI: 61.1%–86%) in predicting ESRD. Conclusion: In our environment, a child with initial creatinine value of less than 102 μmol/L may be classified as unlikely to develop ESRD. Additionally, a nadir creatinine greater than 89 μmol/L may increase the probability of developing ESRD. While nadir creatinine has consistently been identified as independent indicator of outcome, its value is evaluated after a year of management; however, early indicator like creatinine at diagnosis may provide essential monitoring information at the onset of treatment. Keywords: PUV, ESRD, Nadir creatinine, Creatinine at diagnosis