Primary Vesicoureteral Reflux and Renal Scarring

Impact of Urinary Tract Infection on Progression of Renal Scars and Formation of New Scars in Patients with Primary Vesicoureteric Reflux

INTRODUCTION

Primary vesicoureteric reflux (VUR) is a prevalent cause of end-stage renal failure in children. Scars on radionuclide imaging indicate irreparable damage to the growing kidneys. This study aims to determine whether a urinary tract infection (UTI) associated with primary VUR promotes the development of new renal scars or progression in the pre-existing ones.

MATERIALS AND METHODS

Children with primary VUR on continuous antibiotic prophylaxis at a tertiary teaching hospital's paediatric nephrourology clinic were observed prospectively. At recruitment, a renal cortical (dimercaptosuccinic acid [DMSA]) scan was done, and the children were followed up every 3 months. Breakthrough UTIs were documented, and follow-up DMSA scans were performed to document new scarring/grade advancement of existing scars in the renoureteric units (RUUs).

RESULTS

Seventy-two RUUs in 36 patients were monitored. Fifty-four (75%) RUUs were exposed to VUR of different grades, and 46 (85.1%) had a UTI. On the DMSA scan, these showed new scar development in 10/18 (55%) RUUs and scar progression in 13/28 (46.4%) RUUs. Of the 8 RUUs with VUR and without UTI, new scars manifest in 4/5 (80%) and progressed in 1/3 (33%). On univariate analysis, there was no significant difference in the formation of new scars or scar advancement on the DMSA scan between RUU with VUR and UTI and those without UTI. There was a significant positive correlation between the scarring on DMSA scan and the grade of reflux (P < 0.001).

CONCLUSION

Primary VUR patients had fresh or progressed scarring regardless of urinary infection. A higher VUR grade at presentation was a significant risk factor for scarring.

Nadir Creatinine in Congenital Anomalies of the Kidney and Urinary Tract (CAKUT): A Single-Center Experience

BACKGROUND/OBJECTIVES

Congenital anomalies of the kidney and urinary tract (CAKUT) are the main cause of chronic kidney disease (CKD) requiring renal replacement therapy (RRT) in children, being the leading cause (50-70%) of end-stage renal disease (ESRD) in children and young adults. Our study aimed to assess the natural evolution of various antenatally diagnosed renal malformations and to identify potential prognostic factors to guide the therapeutic management of patients with CAKUT.

METHODS

We conducted a retrospective study on 205 children with CAKUT. For each patient, analyzing their medical records, we established the nadir value of serum creatinine, defined as the lowest creatinine level during the first year of life. We assessed the value of nadir creatinine as a prognostic marker in patients with CAKUT, and using an ROC curve, we also determined a threshold value of nadir creatinine that predicted progression to ESRD.

RESULTS

The male-to-female ratio was 2.8 to 1. The mean gestational age at detection was 29.85 weeks (±6.71). A total of 36 patients (17.6%) had impaired renal function, of which 8 (3.9% of the total) progressed to ESRD. The mean nadir creatinine in patients with ESRD was 1.39 mg/dL. A nadir creatinine cut-off of 0.98 mg/dL had high sensitivity and specificity in identifying patients with progression to ESRD, with an AUC of 0.95 and a 95% confidence interval between 0.86 and 1.05 mg/dL.

CONCLUSIONS

Our results support the value of nadir creatinine in predicting progression to ESRD, consistent with previously published data.

Risk factors for new renal scarring in children with vesicoureteral reflux receiving continuous antibiotic prophylaxis

To investigate the risk factors for new renal scarring (NRS) in children with vesicoureteral reflux (VUR) receiving continuous antibiotic prophylaxis (CAP). This was a single-center cohort study. The clinical data of 140 children with grade I-V VUR receiving CAP were analyzed. In this study, exposure variables were sex, younger age at the initial diagnosis of UTI ≤ 12 months, the occurrence of breakthrough urinary tract infection (BT-UTI), high-grade VUR, bilateral VUR, etiology, presence of renal scarring at the initial diagnosis and ultrasound abnormalities. The outcome was NRS. A total of 140 children were included in the risk factor analysis of NRS, 73 of whom experienced NRS, an incidence rate of 52.14%. Multivariate Cox regression suggested that the presence of renal function impairment after the initial diagnosis of UTI (OR 3.411, 95% CI 1.5751-6.646) and the occurrence of BT-UTI while receiving CAP (OR 1.995, 95% CI 1.089-2.958) were independent risk factors for NRS. Multivariate Cox regression showed that high-grade VUR had no significant effects on NRS (OR 0.940, 95% CI 0.462-1.912, P = 0.864). No significant difference was identified in multivariate Cox regression analysis in the IV-V group (vs I-III group) (OR 0.960, 95% CI 0.565-1.633, P = 0.960). Renal function impairment after the initial diagnosis of UTI and the occurrence of BT-UTI while receiving CAP were independent risk factors for NRS. Neither univariate analysis nor multivariate analysis found a correlation between VUR grade and NRS.

Therapeutic Management of Children with Vesicoureteral Reflux

Contrasting data refer to therapies for vesicoureteral reflux (VUR), such as surgical treatments and continuous antibiotic prophylaxis (CAP). This study evaluated the effectiveness of these approaches in children with VUR, analyzing the recurrence of febrile urinary tract infections (UTIs) and the resolution of VUR after the treatment. A total of 350 pediatric patients underwent contrast-enhanced voiding urosonography (ceVUS) to diagnose a VUR, whereas renal scintigraphy evaluated potential scars. After 12 months from the treatment, the VUR, the relapse of febrile UTIs, and reflux-related nephropathy were analyzed. Twenty-seven children had recurrent febrile UTIs after surgical therapy, with a greater rate of relapses observed in III and V VUR grades. Thirteen patients who underwent surgery had scars, independently of VUR grades and gender, with evidence of chronic renal failure at the end of the follow-up period. A total of 140 subjects were treated with CAP, and 30% of them continued to suffer from febrile UTIs. Ninety-five patients with VUR underwent ceVUS after 12 months, with persistent reflux in fifty-two patients. All of them had severe VUR, correlating with the age at diagnosis and gender. CAP therapy prevented scarring better than surgery, especially in children with III and V grades of VUR. A late onset of VUR or VUR involving neonatal patients is rarely a reversible process. This study identified predictors of success or failure of surgical or CAP therapies, evaluating the relapse of UTIs or persistent reflux after the treatment and giving prognostic information in children with VUR.

The Utility of Noninvasive Urinary Biomarkers for the Evaluation of Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is one of the most important disorders encountered in pediatric nephrology due to its frequency and potential evolution to chronic kidney disease (CKD). The aim of our study was to identify noninvasive and easy-to-determine urinary markers to facilitate the diagnosis and staging of VUR. We performed a cross-section study including 39 patients with VUR followed over three years (August 2021-September 2023) and 39 children without urinary disorder (the control group). We measured the urinary concentration of interleukin-6 (IL-6), cathelicidin (LL-37), and neutrophil gelatinase-associated lipocalin (NGAL) in VUR and healthy controls. Moreover, we analyzed the correlation between these biomarkers and the presence of renal scars (RS), reflux nephropathy (RN), and CKD. The NGAL concentrations were significantly higher in patients with VUR than in the controls (p = 0.02). Regarding the severity of the reflux, NGAL/creatinine and LL-37/creatinine were positively correlated with severe reflux (p = 0.04, respectively, p = 0.02). In patients with VUR and RS, LL-37/creatinine was significantly lower (p = 0.01). LL-37/creatinine with an AUC of 0.71 and NGAL/creatinine with an AUC of 0.72 could be acceptable diagnostic tests for severe VUR. In conclusion, urinary IL-6, NGAL, and LL-37 could serve as valuable markers for diagnosing and predicting outcomes in patients with VUR and RN.

Vesicoureteral Reflux and Innate Immune System: Physiology, Physiopathology, and Clinical Aspects

Vesicoureteral reflux represents one of the most concerning topics in pediatric nephrology due to its frequency, clinical expression with the potential to evolve into chronic kidney disease, and last but not least, its socio-economic implications. The presence of vesicoureteral reflux, the occurrence of urinary tract infections, and the development of reflux nephropathy, hypertension, chronic kidney disease, and finally, end-stage renal disease represent a progressive spectrum of a single physiopathological condition. For the proper management of these patients with the best clinical outcomes, and in an attempt to prevent the spread of uropathogens' resistance to antibacterial therapy, we must better understand the physiopathology of urinary tract infections in patients with vesicoureteral reflux, and at the same time, we should acknowledge the implication and response of the innate immune system in this progressive pathological condition. The present paper focuses on theoretical aspects regarding the physiopathology of vesicoureteral reflux and the interconditionality between urinary tract infections and the innate immune system. In addition, we detailed aspects regarding cytokines, interleukins, antimicrobial peptides, and proteins involved in the innate immune response as well as their implications in the physiopathology of reflux nephropathy. New directions of study should focus on using these innate immune system effectors as diagnostic and therapeutic tools in renal pathology.