Changes in differential renal function after pyeloplasty in children.

Purpose: Previous series showed controversial differential renal function outcomes after pyeloplasty in children. However, they were limited by study power, methodology and lack of comparable end points. We determined the status of differential renal function after pyeloplasty in children in what is to our knowledge the largest series to date.

Materials And Methods: After excluding patients with renal anomalies, solitary kidney or bilateral pyeloplasty from analysis, we retrospectively identified 196 younger than 18 years who were treated with pyeloplasty between May 2002 and January 2010 and had preoperative and postoperative renal scintigraphy available. Primary outcome measures were greater than 5% improvement in baseline differential renal function and baseline weighted differential renal function at last followup. Clinical variables predicting outcome measures were determined using univariable and multivariable analyses.

Results: During a median followup of 12 months, mean ± SD differential renal function improved from 35.8% ± 10% to 38.7% ± 11% (p <0.001). In the poor and intermediate groups baseline differential renal function improved, while in the good group function was static postoperatively (p <0.001). The linear regression model showed that only baseline differential renal function explained the variance in baseline weighted differential renal function (β = -0.393, p <0.001). In the Cox proportional hazards model baseline differential renal function (less than 35% HR 3.196, p <0.001 and 35% to 40% HR 2.733, p = 0.002) and cortical thickness (HR 2.114, p = 0.029) were the only predictors of a greater than 5% improvement in postoperative differential renal function.

Conclusions: Renal function improves after pyeloplasty in children. Baseline differential renal function and cortical thickness predict improvement after surgery.