Adding Renal Scan Data Improves the Accuracy of a Computational Model to Predict Vesicoureteral Reflux Resolution

Comparison of diagnostic accuracy of models combining the renal biomarkers in predicting renal scarring in pediatric population with vesicoureteral reflux (VUR)

INTRODUCTION

Renal scarring is prominently observed in children with vesicoureteral reflux (VUR) and can lead to complicated renal outcomes. Although biopsy is the gold standard to detect renal scarring, it is an invasive procedure. There are established renal biomarkers which can help detect renal scarring. Individual biomarkers have not shown to have extensively good discriminatory ability for this.

AIM

This paper aims at combining the values of multiple biomarkers in models to detect renal scarring.

METHODOLOGY

Secondary data with the values of renal biomarkers like kidney injury molecule-1, neutrophil gelatinase-associated lipocalin (NGAL), and urinary creatinine along with the renal scarring status was considered. Logistic regression, discriminant analysis, Bayesian logistic regression, Naïve Bayes, and decision tree models were developed with these markers. The discriminatory ability of individual biomarkers along with the models was assessed using the area under the curve from ROC curve. Sensitivity, specificity, and misclassification rates were estimated and compared.

RESULTS

NGAL was the most predominant renal biomarker in classifying the patients with renal scarring (AUC: 0.77 (0.67, 0.87); p value < 0.001). Each of the model performed better than individual biomarkers. Decision tree (AUC: 0.83 (0.74, 0.91); p value < 0.001) and Naïve Bayes model (misclassification rate = 20.2%) performed the best amongst the models.

CONCLUSION

Combining the values of renal biomarkers through a statistical or machine learning model to detect renal scarring is a better approach as compared to considering individual renal biomarkers.

Management of Vesicoureteral Reflux: What Have We Learned Over the Last 20 Years?

Vesicoureteral reflux (VUR) is associated with increased risks of urinary tract infection, renal scarring and reflux nephropathy. We review advancements over the last two decades in our understanding and management of VUR. Over time, the condition may resolve spontaneously but it can persist for many years and bladder/bowel dysfunction is often involved. Some factors that increase the likelihood of persistence (e.g., high grade) also increase the risk of renal scarring. Voiding cystourethrography (VCUG) is generally considered the definitive method for diagnosing VUR, and helpful in determining the need for treatment. However, this procedure causes distress and radiation exposure. Therefore, strategies to reduce clinicians' reliance upon VCUG (e.g., after a VUR treatment procedure) have been developed. There are several options for managing patients with VUR. Observation is suitable only for patients at low risk of renal injury. Antibiotic prophylaxis can reduce the incidence of UTIs, but drawbacks such as antibiotic resistance and incomplete adherence mean that this option is not viable for long-term use. Long-term studies of endoscopic injection have helped us understand factors influencing use and the effectiveness of this procedure. Ureteral reimplantation is still performed commonly, and robot-assisted laparoscopic methods are gaining popularity. Over the last 20 years, there has been a shift toward more conservative management of VUR with an individualized, risk-based approach. For continued treatment improvement, better identification of children at risk of renal scarring, robust evidence regarding the available interventions, and an improved VUR grading system are needed.

A scoring system for predicting downgrading and resolution of high-grade infant vesicoureteral reflux

AIM

Aim of the study was to provide a scoring system for predicting downgrading and resolution of infantile high-grade vesicoureteral reflux (VUR).

METHODS

Eighty-nine infants (65 boys) with high-grade VUR (grade 4-5) diagnosed at median age 2.5 months and followed to 39 months had repeated investigations of VUR grade, renal damage/function and bladder function. Recurrent urinary tract infections (UTIs) were registered. Risk variables collected at 1 year were analysed as independent factors for spontaneous resolution to grades ≤2 and 0, using univariable/multivariable logistic regression.

RESULTS

A scoring system was built with a total of 14 points from four independent risk factors (sex, breakthrough UTI, type of renal damage and subnormal glomerular filtration rate). Children with persistent VUR (grade 3-5) had higher scores compared with the group with spontaneous resolution (grade 0-2) (mean 7.9 vs. 4.5, P < .0001). A score of ≥8 points indicated a low probability of VUR resolution (≤14%). The model was considered excellent based on area under the ROC curve (0.82) and showed satisfactory internal validity.

CONCLUSION

This model provides a practical tool in the management of infants born with high-grade reflux. High scores at one year of age indicate a high risk of persistent dilated reflux.

Critical analysis of the outcome of primary unilateral vesicoureteral reflux in a medium volume center

Background

Vesicoureteral reflux (VUR) is a common finding in pediatric age group. Here in we explored the possible risk factors that affect the rate of resolution in patients with primary unilateral VUR under conservative treatment.

Methods

Between 2006 and 2014, we retrospectively evaluated all VUR patients and included only patients with primary unilateral VUR. Records were reviewed for patient age at diagnosis, antenatal history, patient gender, mode of presentation, side, and grade of VUR, associated hydronephrosis (HN) on renal ultrasound, presence of scarring and split function on dimercaptosuccinic acid (DMSA) scan. Clinical and radiological outcomes were assessed. Both univariate and multivariate analysis were conducted.

Results

A total of 68 patients with primary unilateral VUR were included (32 boys and 36 girls) with a mean age of 10 months (range 1–32). Antenatal HN was detected in 50% of patients. In 15 cases (22%), VUR was of high grade (IV–V). Associated HN was evident in 39 patients (57%). DMSA scans showed renal scarring in 16 patients (23%). After a mean follow-up of 7 years, VUR resolved in 49 patients (72%). Significant predictors for VUR resolution were VUR grade, DMSA split function and associated high-grade HN. High-grade HN with VUR was the only significant independent risk factor.

Conclusions

The rate of resolution in primary unilateral VUR under conservative treatment is significantly affected by VUR grade, DMSA split renal function and the presence of associated HN. Association of high-grade HN with VUR carries a low chance for spontaneous resolution.

Delayed upper tract drainage on voiding cystourethrogram may not be associated with increased risk of urinary tract infection in children with vesicoureteral reflux

INTRODUCTION

Urinary stasis in the setting of obstruction provides an opportunistic environment for bacterial multiplication and is a well-established risk factor for UTI. Vesicoureteral reflux (VUR) with delayed upper tract drainage (UTD) on VCUG has been reported to correlate with increased UTI risk. We sought to determine whether delayed UTD can be reliably classified, and whether it correlates with UTI incidence, VCUG, or endoscopic findings.

METHODS

Children undergoing endoscopic surgery for primary VUR (2009-2012) were identified. VUR grade, timing, and laterality were abstracted. Demographics, hydrodistention (HD) grade, reported febrile and culture-proven UTI were assessed. UTD on VCUG was graded on post-void images as 1 = partial/complete UTD or 2 = no/increased UTD. Inter-observer agreement was calculated. Patients were excluded for incomplete imaging or inability to void during VCUG.

RESULTS

The cohort included 128 patients (10M, 118F), mean age 4.1 ± 2.1 years. Mean age at diagnosis was 2.8 ± 2.8 years. Mean maximum VUR grade was 3 ± 0.9: 1 (7.8%), 2 (20.3%), 3 (43%), 4 (25.8%), 5 (3.1%). UTD occurred in 45 (35%), and no drainage in 83 (65%) patients. Agreement coefficient between graders was 0.596 (p < 0.0001). Cultures were available in 100 patients (70 positive). Patients experienced a mean of 2 ± 1.2 parent-reported fUTIs and 1.2 ± 1.2 culture-proven UTIs from birth to surgery. UTI rate did not differ by UTD status for parent or culture-proven UTI (Table). On multivariate analysis, no patient characteristic was a significant predictor of UTI based on drainage status. Children diagnosed with VUR before 1 year of age had a higher verified UTI rate (p < 0.001). However, drainage was not a significant predictor of UTI rate and when testing the interaction of drainage and age.

CONCLUSION

We sought to determine whether UTD was an accurate predictor of UTI risk to maximize available prognostic information from a single VCUG. Delayed UTD was not a predictor of infection in our patients, nor was it associated with previously described UTI risk factors, such as VUR timing or grade, and voiding dysfunction. Limitations included the retrospective nature of the study in patients undergoing endoscopic VUR treatment, and possible inaccurate UTI reports from parents and pediatricians. UTD can be reliably scored using a binary system with high inter-observer correlation. Our data call into question the previous finding that children with poor UTD are at increased risk of recurrent UTI. Delayed UTD is also not associated with higher HD, or VUR grade compared with those with more prompt UTD.

Computer model predicting breakthrough febrile urinary tract infection in children with primary vesicoureteral reflux

INTRODUCTION AND OBJECTIVE

Factors influencing the decision to surgically correct vesicoureteral reflux (VUR) include risk of breakthrough febrile urinary tract infection (fUTI) or renal scarring, and decreased likelihood of spontaneous resolution. Improved identification of children at risk for recurrent fUTI may impact management decisions, and allow for more individualized VUR management. We have developed and investigated the accuracy of a multivariable computational model to predict probability of breakthrough fUTI in children with primary VUR.

STUDY DESIGN

Children with primary VUR and detailed clinical and voiding cystourethrogram (VCUG) data were identified. Patient demographics, VCUG findings including grade, laterality, and bladder volume at onset of VUR, UTI history, presence of bladder-bowel dysfunction (BBD), and breakthrough fUTI were assessed. The VCUG dataset was randomized into a training set of 288 with a separate representational cross-validation set of 96. Various model types and architectures were investigated using neUROn++, a set of C++ programs.

RESULTS

Two hundred fifty-five children (208 girls, 47 boys) diagnosed with primary VUR at a mean age of 3.1 years (±2.6) met all inclusion criteria. A total 384 VCUGs were analyzed. Median follow-up was 24 months (interquartile range 12-52 months). Sixty-eight children (26.7%) experienced 90 breakthrough fUTI events. Dilating VUR, reflux occurring at low bladder volumes, BBD, and history of multiple infections/fUTI were associated with breakthrough fUTI (Table). A 2-hidden node neural network model had the best fit with a receiver operating characteristic curve area of 0.755 for predicting breakthrough fUTI.

DISCUSSION

The risk of recurrent febrile infections, renal parenchymal scarring, and likelihood of spontaneous resolution, as well as parental preference all influence management of primary VUR. The genesis of UTI is multifactorial, making precise prediction of an individual child's risk of breakthrough fUTI challenging. Demonstrated risk factors for UTI include age, gender, VUR grade, reflux at low bladder volume, BBD, and UTI history. We developed a prognostic calculator using a multivariable model with 76% accuracy that can be deployed for availability on the Internet, allowing input variables to be entered to calculate the odds of an individual child developing a breakthrough fUTI.

CONCLUSIONS

A computational model using multiple variables including bladder volume at onset of VUR provides individualized prediction of children at risk for breakthrough fUTI. A web-based prognostic calculator based on this model will provide a useful tool for assessing personalized risk of breakthrough fUTI in children with primary VUR.

Vesicoureteral reflux index (VURx): a novel tool to predict primary reflux improvement and resolution in children less than 2 years of age

PURPOSE

Surgical correction of vesicoureteral reflux (VUR) is influenced by recurrent urinary tract infection (UTI) risk and the likelihood of spontaneous resolution. We aimed to identify factors associated with VUR resolution in children less than 2 years of age and to design a simple scoring tool to predict improvement and resolution.

MATERIALS AND METHODS

Children less than 2 years old with primary VUR were identified. Patient demographics, voiding cystourethrogram (VCUG) findings and clinical outcomes over time were assessed. Multivariate analysis with time to resolution was performed to identify factors predictive of VUR improvement and resolution. A random forest model was used to confirm the VUR index (VURx) with normalized importance.

RESULTS

Two-hundred and twenty-nine children met all inclusion criteria. Mean age at initial VCUG was 0.46±0.43 years. Median clinical follow-up was 1.6 years (range 0.5-4.4 years). Children with grade 4-5 reflux, complete ureteral duplication or periureteral diverticula, and filling phase VUR, as well as female gender, had significantly (p<0.01) longer time to improvement or resolution on multivariate survival analysis. VURx 1 to 5-6 had improvement/resolution rates of 89%, 69%, 53%, 16% and 11%, respectively.

CONCLUSIONS

Female gender, high-grade VUR, ureteral anomalies, and filling reflux are associated with longer time to improvement and non-resolution. VURx reliably predicts resolution of primary reflux in children less than 2 years of age.

Vesicoureteral Reflux in Pediatric Age: Where are we Today?

Although the diagnosis of vesicoureteral reflux and of reflux nephropathy is a well-established and shared procedure, its treatment nowadays is still very controversial. New developments on the knowledge of pathophysiology of renal damage associated to reflux opened the way towards a different diagnostic work-up and different therapeutic approaches.

Recently, the “top-down” diagnostic approach has gained wider interest, versus the “down-top” protocol. The attention has recently focused on the renal parenchyma damage and less interest has been given to the presence and the radiological degree of vesicoureteral reflux.

The review criteria were based on an in-depth search of references conducted on PubMed, using the terms “vesicoureteral reflux”, “children”, “incidence”, “etiology”, “diagnosis”, “treatment” and “outcomes”. The selection of the papers cited in this review was influenced by the content and the relevance to the points focused in the article.

Conservative approaches include no treatment option with watchful waiting, long-term antibiotic prophylaxis and bladder rehabilitation. The operative treatment consists of endoscopic, open, laparoscopic and robotic procedures to stop the refluxing ureter.

No final consensus has been achieved in literature yet, and further studies are necessary in order to better define the subset of children at risk of developing progression of renal damage.

This review aims to clarify the diagnostic management and the urological-nephrological treatment of reflux in pediatric age, on the basis of a review of the best-published evidence.

Predictive risk factors in childhood urinary tract infection, vesicoureteral reflux, and renal scarring management

Approaches to the management of children with urinary tract infection (UTI), vesicoureteral reflux (VUR), and renal scars have been challenged and have become controversial over the past decade. It is difficult to determine when, how, and which patients will benefit from the diagnosis and management of this condition. Therefore, the issues of diagnostic imaging, observation, follow-up, and intervention tend to be decided more on a case-by-case basis, rather than by using an algorithm. Over the past few years, there have been advances in the identification of risk factors that predispose patients with UTI to present with VUR, to develop recurrent UTIs and renal scars, to have deteriorating renal function, to show VUR improvement and/or spontaneous resolution, and to be candidates for and benefit from early surgical intervention.

Individualizing management of vesicoureteral reflux

BACKGROUND

Approaches to the management of vesicoureteral reflux (VUR) in children have changed rapidly in recent years. Multiple studies published over the last decade have contributed to these changes by challenging the dogma that all children with reflux require and benefit from continuous antibiotic prophylaxis. The advent and wide acceptance of endoscopic treatment for VUR has also contributed to these changes. Although new guidelines for VUR management have recently been proposed, they are broad and relatively non-specific. Many physicians and parents remain unsure which children are at risk from their VUR, and which would benefit from antibiotic prophylaxis or surgical intervention.

MATERIALS AND METHODS

A literature search, followed by an additional search based on bibliographies, was performed for articles reporting on VUR and the utility of antibiotic prophylaxis for its treatment, as well as the chance of spontaneous resolution.

RESULTS

Articles selected for review included those that provided information to assist physicians in determining if a child with VUR is at increased risk of pyelonephritis or persistent VUR, and would benefit from intervention. Particular emphasis was placed on recent prospective, randomized trials in children with VUR.

CONCLUSIONS

Because of the multiple factors affecting risk in a child with VUR, specific guidelines for intervention cannot be provided. However, an accurate understanding of these risk factors will help the physician and parents to develop a more individualized management plan for a child with VUR.

The prognostic impact of an abnormal initial renal ultrasound on early reflux resolution

OBJECTIVE

In a group of children diagnosed with vesicoureteral reflux (VUR) we evaluated renal ultrasound findings, associated findings on renal scan, and prognostic impact on VUR resolution.

METHODS

Medical records were reviewed for children with primary reflux and no history of antenatal hydronephrosis who underwent an initial renal ultrasound. Abnormal renal ultrasound was defined as hydronephrosis or relative difference in renal size ≥1 cm. Reflux resolution was evaluated at 2 years post diagnosis.

RESULTS

In 129 children with VUR (111 girls, 18 boys), 39 (30%) had an abnormal renal ultrasound. Two-year VUR resolution in the abnormal renal ultrasound group was 21% versus 46% in the group with normal renal ultrasound (P = 0.01). Combining grade II and III reflux, an abnormal ultrasound was associated with a statistically significantly lower resolution rate (grade II-III 23% vs 47%, P = 0.049). For children with moderate hydronephrosis, 8/9 (89%) had abnormal initial renal scans and all failed to achieve resolution of reflux at 2 years.

CONCLUSIONS

In this cohort of children with VUR, 30% had abnormalities on renal ultrasound. The presence of moderate hydronephrosis on ultrasound may indicate a high likelihood of abnormality on renal scan and failure to achieve early resolution of VUR.

Variation among internet based calculators in predicting spontaneous resolution of vesicoureteral reflux

PURPOSE

An increasing number of parents and practitioners use the Internet for health related purposes, and an increasing number of models are available on the Internet for predicting spontaneous resolution rates for children with vesicoureteral reflux. We sought to determine whether currently available Internet based calculators for vesicoureteral reflux resolution produce systematically different results.

MATERIALS AND METHODS

Following a systematic Internet search we identified 3 Internet based calculators of spontaneous resolution rates for children with vesicoureteral reflux, of which 2 were academic affiliated and 1 was industry affiliated. We generated a random cohort of 100 hypothetical patients with a wide range of clinical characteristics and entered the data on each patient into each calculator. We then compared the results from the calculators in terms of mean predicted resolution probability and number of cases deemed likely to resolve at various cutoff probabilities.

RESULTS

Mean predicted resolution probabilities were 41% and 36% (range 31% to 41%) for the 2 academic affiliated calculators and 33% for the industry affiliated calculator (p = 0.02). For some patients the calculators produced markedly different probabilities of spontaneous resolution, in some instances ranging from 24% to 89% for the same patient. At thresholds greater than 5%, 10% and 25% probability of spontaneous resolution the calculators differed significantly regarding whether cases would resolve (all p <0.0001).

CONCLUSIONS

Predicted probabilities of spontaneous resolution of vesicoureteral reflux differ significantly among Internet based calculators. For certain patients, particularly those with a lower probability of spontaneous resolution, these differences can significantly influence clinical decision making.

Improvement in vesicoureteral reflux grade on serial imaging predicts resolution

PURPOSE

When children are initially diagnosed with vesicoureteral reflux most undergo a period of antibiotic prophylaxis followed by serial imaging. Although improvement in reflux grade through time presumably predicts eventual resolution, the significance of changing grade through time is unknown. We examined whether improvement in reflux on serial imaging predicts resolution.

MATERIALS AND METHODS

We retrospectively reviewed 1,761 children diagnosed with vesicoureteral reflux, of whom 965 had a minimum of 2 years of followup. We examined initial reflux grade and grade on serial imaging up to 5 years after the original diagnosis. For each child it was determined whether reflux was resolved, eventually resolved or never resolved. Groups were further stratified by clinical characteristics.

RESULTS

Multivariate analysis revealed that male gender (HR 1.33, p = 0.05), age younger than 1 year at diagnosis (HR 1.35, p = 0.004), lower grade at presentation (grade I HR 2.2, grade II HR 1.96, grade III HR 1.33; p <0.001) and unilateral reflux (HR 1.39, p = 0.001) were all independent predictors of reflux resolution. Multivariate analysis also showed that reflux improvement on imaging 1 year after diagnosis (HR 3.14, p <0.0001) and improvement from the previous year at any point during followup (HR 1.8, p = 0.009) were independent predictors of reflux resolution.

CONCLUSIONS

Consistent with previous findings, male gender, lower reflux grade at presentation, age less than 1 year at presentation and unilateral reflux were all predictive of reflux resolution. Our analysis also demonstrated that improvement in reflux grade on imaging study 1 year after diagnosis was predictive of resolution, and that reflux improvement from the previous year at any point during followup was an independent predictor of resolution. This information will prove valuable in clinical counseling and therapeutic decision making.

Diagnosis and management of vesicoureteral reflux in children

Critical evaluation of previously accepted dogma regarding the evaluation and treatment of vesicoureteral reflux (VUR) has raised significant questions regarding all aspects of VUR management. Whereas the standard of care previously consisted of antibiotic prophylaxis for any child with VUR, it is now unclear which children, if any, truly benefit from antibiotic prophylaxis. Operative intervention for VUR constitutes overtreatment in many children, yet there are limited data available to indicate which children benefit from VUR correction through decreased rates of adverse long-term clinical sequelae. Studies with longer follow-up demonstrate decreased efficacy of endoscopic therapy that was previously hoped to approach the success of ureteroneocystostomy. Prospective studies might identify risk factors for pyelonephritis and renal scarring without antibiotic prophylaxis. Careful retrospective reviews of adults with a history of reflux might allow childhood risk factors for adverse sequelae to be characterized. Through analysis of multiple characteristics, better clinical management of VUR on an individualized basis will become the new standard of care.