Renal outcome among children with posterior urethral valve: When to worry?

Insight into prevalence, etiology, and modalities of pediatric chronic dialysis: a comprehensive nationwide analysis

BACKGROUND

This study aimed to determine the prevalence and etiology of kidney failure (KF) among children below 15 years of age receiving chronic dialysis in Saudi Arabia and describe their dialysis modalities.

METHODS

This cross-sectional descriptive study was conducted on 8 August 2022, encompassing all 23 pediatric dialysis centers in Saudi Arabia. Data gathered comprised patient demographics, causes of KF, and the dialysis methods employed. Collected data underwent analysis to determine prevalence of children undergoing chronic dialysis, discern underlying causes of KF, and evaluate distribution of patients across different dialysis modalities.

RESULTS

The prevalence of children on chronic dialysis is 77.6 per million children living in Saudi Arabia, equating to 419 children. The predominant underlying cause of KF was congenital anomalies of the kidneys and urinary tract (CAKUT), representing a substantial 41% of cases. Following this, others or unknown etiologies accounted for a noteworthy 25% of cases, with focal segmental glomerulosclerosis (FSGS) comprising 13%, glomerulonephritis at 11%, and congenital nephrotic syndrome contributing 10% to etiological distribution. Regarding dialysis modalities employed, 67% of patients were on peritoneal dialysis (PD), while the remaining 33% were on hemodialysis (HD).

CONCLUSIONS

This first nationwide study of pediatric chronic dialysis in Saudi Arabia sheds light on the prevalence of children undergoing chronic dialysis and underlying causes of their KF, thereby contributing to our understanding of clinical management considerations. This research serves as a stepping stone for the development of national registries.

Pop-off mechanisms as renoprotective mediators in children with posterior urethral valves: A systematic review and meta-analysis

BACKGROUND

Pop-off mechanisms are potential pressure-relieving mediators in patients diagnosed with posterior urethral valves (PUV). This systematic review aimed to synthesize the existing evidence regarding the protective effect of pop-off mechanisms on renal function in children with PUV.

METHODS

We conducted a systematic review of the literature that involved an extensive search in the main databases of the medical bibliography. Three independent reviewers selected the relevant articles. Methodological quality was rated using the Newcastle Ottawa Scale index. We used random meta-analyses to compare different outcomes (serum creatine, Nadir serum creatinine, and Chronic Kidney Disease) between children with PUV and pop-off mechanisms and those with PUV without pop-off mechanisms.

RESULTS

10 studies with data from 896 participants were included in this review. Seven articles reported serum creatinine values for each group and 3 of them found significant differences between groups. The random-effects meta-analysis for serum creatinine showed significant lower mean (diff = -52.88 μmol/L [95 % CI -73.65 to -32.11]) in the group of children with pop-off mechanisms, and the random-effects meta-analysis for Nadir serum creatinine showed a marginally significantly lower mean in the group of children with pop-off mechanisms (diff = -12.00 μmol/L [95 % CI -24.04 to 0.04]). The random-effect meta-analysis for Chronic Kidney Disease resulted in a significant risk reduction for the group of children with pop-off mechanisms (odds ratio = 0.48 [95 % CI 0.23 to 0.98]).

CONCLUSIONS

Children with PUV and pop-off mechanisms show better renal function and lower risk of Chronic Kidney Disease than those with PUV without pop-off mechanisms suggesting these mechanisms may act as renoprotective mediators. The high heterogeneity between studies in the assessment of renal function and long-term outcomes calls for a cautious interpretation of these findings. Future studies that stratify by different types of pop-off mechanisms and use standardized metrics, such as Nadir creatinine, are needed.

Implementation of a standardized clinical pathway in a dedicated posterior urethral valves clinic: short-term outcomes

BACKGROUND

To determine if the implementation of a posterior urethral valves (PUV) clinic and standardized management pathway improves the short-term kidney outcomes of infants with PUV.

METHODS

From 2016-2022, 50 consecutive patients were divided into groups after the implementation of the clinic (APUV, n = 29) and before (BPUV, n = 21) during a comparable timeframe. Assessed data included age at initial visit, timing and type of surgery, frequency of follow-up visits, medications, nadir creatinine, and development of CKD/kidney failure. Data are shown as median with interquartile range (IQR) and odds ratios (OR) with 95% confidence interval (CI).

RESULTS

APUV had higher rates of prenatal diagnoses (12/29 vs. 1/21; p = 0.0037), earlier initial surgical intervention (8 days; IQR 0, 105 vs. 33 days; IQR 4, 603; p < 0.0001), and higher rates of primary diversions (10/29 vs. 0/21; p = 0.0028). Standardized management led to earlier initiation of alpha blockers (326 days; IQR 6, 860 vs. 991; IQR 149, 1634; p = 0.0019) and anticholinergics (57 days; IQR 3, 860 vs. 1283 days; IQR 477, 1718; p < 0.0001). Nadir creatinine was reached at earlier ages in APUV (105 days; IQR 2, 303 vs. 164 days; IQR 21, 447; p = 0.0192 BPUV). One patient progressed to CKD5 in APUV compared to CKD3, CKD5 and one transplant in BPUV.

CONCLUSION

Implementing the PUV clinic with standardized treatment expedited postnatal management and resulted in a higher number of cases detected prenatally, a shift in primary treatment, younger ages at initial treatment, reduced time to nadir creatinine, and timely initiation of supportive medications. A higher resolution version of the Graphical abstract is available as Supplementary information.

Primary ablation versus urinary diversion in posterior urethral valve: Systematic review and meta-analysis

PURPOSE

To determine differences in long-term kidney and bladder outcomes in boys with posterior urethral valves (PUV) managed by a primary valve ablation or primary urinary diversion.

MATERIALS AND METHODS

A systematic search was performed in March 2021. Comparative studies were evaluated according to Cochrane collaboration recommendations. Assessed measures included kidney outcomes (chronic kidney disease, end-stage renal disease, kidney function) and bladder outcomes. Odds ratios (OR) and mean difference (MD) with 95% confidence interval (CI) were extrapolated from available data for quantitative synthesis. Random-effects meta-analysis and meta-regression were performed according to study design, and potential covariates were assessed with subgroup analysis. The systematic review was prospectively registered on PROSPERO (CRD42021243967).

RESULTS

Thirty unique studies describing 1547 boys with PUV were included in this synthesis. Overall effect estimates demonstrate that patients undergoing primary diversion have significantly increased odds of developing renal insufficiency [OR 0.60, 95% CI 0.44, 0.80; p < 0.001]. However, when adjusting for baseline kidney function between intervention groups, there was no significant difference in long term kidney outcomes [p = 0.09, 0.35], or the development of bladder dysfunction or requiring clean-intermittent catheterization with primary ablation rather than diversion [OR 0.89, 95% CI 0.49, 1.59; p = 0.68].

CONCLUSIONS

Current low-quality evidence suggests that medium-term kidney outcomes in children are similar between primary ablation and primary diversion after adjusting for baseline kidney function, while bladder outcomes are highly heterogenous. Further research with covariate control is warranted to investigate sources of heterogeneity.

LEVEL OF EVIDENCE

Level III.

The effect of primary urinary diversion on kidney function in posterior urethral valve: A matched comparison

OBJECTIVE

To determine long-term kidney outcomes in boys with posterior urethral valve (PUV) undergoing either primary valve ablation or urinary diversion with matched baseline kidney function.

METHODS

After retrospective review of patients managed for PUV at our institution, propensity score matched analysis was conducted using nadir serum creatinine with logistic regression analysis. Nearest neighbor matching was used to allocate boys to primary urinary diversion and primary ablation groups. Primary outcomes included kidney function by creatinine or estimated glomerular filtration rate, chronic kidney disease, and end-stage renal disease. Comparative statistics by odds ratio (OR) and hazard ratios on survival analysis were calculated.

RESULTS

A total of 21 boys undergoing primary diversion were matched with 42 boys undergoing ablation using nadir serum creatinine and follow-up time with a median follow-up of 4.8 years. After matching, there was no significant difference in last follow-up kidney function by creatinine (P = .99) or estimated glomerular filtration rate (P = .98). Primary diversion was not associated with increased likelihood of developing chronic kidney disease stage 3 (OR 1.33; P = .31) or end-stage renal disease (OR 1.88; P = .35 and hazard ratios 1.85; P = .30) compared to primary ablation.

CONCLUSIONS

Our propensity matched study suggests that long-term kidney function and kidney outcomes are similar between primary ablation and primary diversion after adjusting for baseline kidney function in boys with PUV.

Mid-short-term risk factors for chronic renal failure in children with posterior urethral valve

OBJECTIVES

To analyze the mid-short-term risk factors for chronic renal failure (CRF) in children with posterior urethral valve (PUV) after valve ablation.

MATERIALS AND METHODS

A retrospective study of 143 patients with PUV who underwent operation was performed. Patients were divided into CRF group (n = 39) and non-CRF group (n = 104). Clinical data of both groups such as the first resection age, last resection age, number of operations, the maximal detrusor pressure (Pdet_max), and vesicoureteral reflux (VUR) were collected and analyzed.

RESULTS

The first resection age, last resection age, and the Pdet_max of patients in the CRF group were higher than those of patients in the non-CRF group (P < 0.05). Multiple regression analysis showed that the indicators related to chronic renal failure were last resection age (β = 1.034, P < 0.05) and Pdet_max (β = 1.068, P < 0.05). The cut-off value of last resection age was 35.5 months, Pdet_max was 41.65 cmH₂O. There was positive correlation of final blood creatinine with last resection age and Pdet_max.

CONCLUSION

The last resection age and Pdet_max are the risk factors of chronic renal failure in children with PUV. A Pdet_max of lower than 41.65 cmH₂O indicates a good prognosis of renal function in patients with PUV.

Comparison of outcomes of prenatal versus postnatal presentation of posterior urethral valves: a systematic review and meta-analysis

OBJECTIVE

To determine through a comprehensive systematic review and meta-analysis the differences in the outcomes of prenatally versus postnatally diagnosed posterior urethral valves (PUV) to ascertain if prenatal detection of PUV has superior outcomes.

METHODS

We conducted a systematic review and meta-analysis in March 2022 (PROSPERO ID - CRD42021243546) and included all studies that reported outcomes of prenatally and postnatally diagnosed PUV. However, for meta-analysis, only those studies that described both groups were included. The main outcomes of interest included progression of chronic kidney disease (CKD), need for renal replacement therapy (RRT) and renal transplant, and bladder dysfunction as determined by initiation of clean intermittent catheterization (CIC). Time to event analyses were completed when possible.

RESULTS

The systematic review included 49 studies (3820 patients). The pooled effect estimates for progression to CKD (OR 0.75 [95% CI 0.43, 1.31]), need for RRT (OR 1.39 [95% CI 0.64, 2.99]) and need for renal transplant (OR 1.64 [95% CI 0.61, 4.42]) between prenatal and postnatal groups was not different. CICs rates were as high as 32% in the prenatal group and 22% in the postnatal group. Most studies had a moderate or serious risk of bias.

CONCLUSION

The existing comparative literature on prenatal versus postnatal presentation of PUV is very heterogeneous. The diagnostic and treatment protocols have not been reported in majority of the studies. The outcome variables are also reported inconsistently. Based on the current evidence, prenatal diagnosis of PUV does not appear to improve the long-term outcomes of these patients.

Posterior urethral valves: Role of prenatal diagnosis and long-term management of bladder function; a single center point of view and review of literature

Posterior Urethral Valves (PUV) are the most common cause of lower urinary tract obstruction. More severe forms are detected early in pregnancy (mainly type I), while other forms are usually discovered later in childhood when investigating lower urinary tract symptoms. Bladder dysfunction is common and is associated with urinary incontinence in about 55% (0%-72%). Despite the removal of the obstruction by urethral valve ablation, pathological changes of the urinary tract can occur with progressive bladder dysfunction, which can cause deterioration of the upper urinary tract as well. For this reason, all children with PUV require long-term follow-up, always until puberty, and in many cases life-long. Therefore, management of PUV is not only limited to obstruction relief, but prevention and treatment of bladder dysfunction, based on urodynamic observations, is paramount. During time, urodynamic patterns may change from detrusor overactivity to decreased compliance/small capacity bladder, to myogenic failure (valve bladder). In the past, an aggressive surgical approach was performed in all patients, and valve resection was considered an emergency procedure. With the development of fetal surgery, vesico-amniotic shunting has been performed as well. Due to improvements of prenatal ultrasound, the presence of PUV is usually already suspected during pregnancy, and subsequent treatment should be performed in high-volume centers, with a multidisciplinary, more conservative approach. This is considered to be more effective and safer. Primary valve ablation is performed after clinical stability and is no longer considered an emergency procedure after birth. During childhood, a multidisciplinary approach (pediatric urologist, nephrologist, urotherapist) is recommended as well in all patients, to improve toilet training, using an advanced urotherapy program with medical treatments and urodynamic evaluations. The aim of this paper is to present our single center experience over 30 years.