In spite of early valve fulguration nearly two third of the children may progress to chronic kidney (CKD) and bladder decompensation secondary to poor bladder contractility (under active detrusor) near puberty. Bladder stabilization remains the main modifiable factor which can alter disease progression and ultimate outcome. In this study, we hypothesized that bladder contractility index (BCI) may be an early marker for future renal deterioration in patients of PUV. CKD III or estimated eGFR of < 45 ml/min/1.73m2  has been reported to be associated with more adverse renal, cardiovascular and clinical outcome. Baseline characteristics and other urodynamic (UDS) parameters were also   evaluated along with primary goal i.e. BCI

Data were expressed as mean±SD (range) or n (%) and compared among the groups by Student t-test or Chi-square test as appropriate. Survival curves were computed using the Kaplan-Meier method and compared between groups using the log-rank test. Univariate and multivariate Cox proportional hazards model was used to analyze factors predicting the event (i.e. eGFR of ≤ 30 ml/min/1.73m2), and to estimate adjusted hazards ratio (HR) with 95% confidence interval (95%CI). Statistical significance was accepted at P value of <0.05. Receiver operating characteristic (ROC) curve analysis of predictors was done to determine optimal cut-off levels with maximum combination of sensitivity and specificity. All analysis was done using SPSS version 16.0 (SPSS Inc, Chicago, IL).

Mean follow-up period was 12.5 years (range 1-15) and median age of patients at the time of evaluation was 5.8 yrs. At the end of the study, 21.8% (59/270) patients had progressed to CKD stage IIIA or more and lifetime risk for developing CKD stage was 45% . Clinical characteristics of patients who developed CKD stage IIIA are compared with those who did not.
Nadir serum creatinine at 1 year after surgery (1.7±0.8 vs. 0.9±0.4, p<0.001) was significantly higher in patients who developed CKD stage IIIA or more (Group I).  Renal survival was significantly better in patients with nadir serum creatinine of ≤ 1 mg/dl at 1 year after surgery as compared to those who had higher values (Figure 2, log rank p=0.012). High grade VUR (18/59 vs. 8/211, p=0.013) and bilateral renal scar (12/59 vs.9/211, p=0.006) were more common in group I. Patients in group I had undergone higher number of bladder augmentation procedures (12/59 vs. 8/211, p=0.001). 
Various measures and calculated indices of CMG done at 1-2 years after surgery are shown and compared.. Mean follow-up period was 8.5 years (range 1-10) and median age of patients at the time of evaluation was 5.8yrs. At the end of the study, 21.8% (59/270) patients had progressed to CKD stage 4-5 and lifetime risk for developing CKD stage was 45% .
  Cox regression analysis of risk factors predicting development of CKD stage IIIA or more. In the multivariate model, bladder contractility index (BCI) (HR, 0.8; p=0.004), end filling pressure (EFP) (HR, 2.1; p=0.010) and ΔC (p=0.020) were significantly associated with the event (i.e. an eGFR of <45 ml/min/1.73m2) whereas BOOI (p=0.053) and bladder BVE (p=0.267) were not (Table 1).
Additionally, nadir serum creatinine at 1 year after surgery (HR, 6.0; p=0.003), high grade VUR (HR, 3.1; p=0.023) and bilateral renal scar (HR, 2.6; p=0.002) were also associated with risk of development of CKD stage IIIA or more. 
Patients were divided into tertiles according to BCI values (i.e. <65, n=94; 65-130, n=84; and >130, n=92) and EFP values (i.e. <10, n=95; 11-15, n=85; and >15, n=90); and survival curves were constructed for each tertile group. Cumulative renal survival was significantly different among the three tertile groups of BCI (, log rank p=0.025) and EFP ( log rank p=0.017) indices. Further, the ROC cut-off levels ((Figure 1) for BCI and EFP were; 75 (AUC±SE, 0.73±0.03, sensitivity of 78.2%, and specificity of 62.5%) and 18 (AUC±SE, 0.65±0.05, sensitivity of 78.6%, and specificity of 64.4%), respectively.

Mean follow-up period was 12.5 years (range 1-15) and median age of patients at the time of evaluation was 5.8 yrs. At the end of the study, 21.8% (59/270) patients had progressed to CKD stage IIIA or more and lifetime risk for developing CKD stage was 45%. Cox regression analysis of risk factors predicting development of CKD stage IIIA.  In the multivariate model, bladder contractility index (BCI) (HR, 0.8; p=0.004),  end filling pressure (EFP) (HR, 2.1; p=0.010) and  ΔC (p=0.020) were significantly associated with the event (i.e. an eGFR of < 45 ml/min/1.73m2) whereas BOOI (p=0.053) and bladder BVE (p=0.267) were not.

Bladder contractility index and end filling pressure are the two important urodynamic indices which can predict early the long term risk of development of CKD stage III in children with PUV.

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