Evaluation of polyuria and polydipsia along with other established prognostic factors in posterior urethral valves for progression to kidney failure: experience from a developing country

Background Up to 50% of children with posterior urethral valves (PUV) progress to kidney failure. This study aimed to evaluate polyuria and polydipsia and other established variables with later development of kidney failure in children with PUV. Methods Retrospective analysis of 297 children with PUV who underwent ablation of valves between January 1992 and January 2015 at our tertiary care center. Patients were divided into two groups: those who developed kidney failure (group 1) and those who did not (group 2). Specific prognostic factors for progression to kidney failure were analyzed including age at presentation < 1 year, nadir serum creatinine > 1.0 mg/dl, bilateral grade 3 or higher VUR at diagnosis, recurrent febrile UTIs, severe bladder dysfunction, polyuria, and polydipsia. Results Thirty-eight (12.8%) patients progressed to kidney failure. Twenty-four and 64 patients were polyuric in group 1 and group 2 respectively ( p < 0.001, Z -4.4666). Twenty-two and 61 patients were polydipsic in both groups respectively ( p < 0.001). On univariate analysis, predicting variables were as follows: age at presentation < 1 year ( p < 0.001), nadir serum creatinine > 1 mg/dl ( p < 0.001), B/L high-grade VUR ( p < 0.001), severe bladder dysfunction ( p < 0.001), recurrent febrile UTIs ( p = 0.002), polyuria ( p < 0.001), and polydipsia ( p < 0.001). On multivariate Cox regression analysis, severe bladder dysfunction, recurrent febrile UTIs, polyuria, and polydipsia were identified as significant prognostic factors predictive of ultimate progression to kidney failure. Conclusion Polyuria and polydipsia along with recurrent febrile UTI and bladder dysfunction are major prognostic factors affecting long-term kidney outcome in cases of PUV. Graphical abstract