Hidden high-grade vesicoureteral reflux is the main risk factor for chronic renal damage in children under the age of two years with first urinary tract infection

Revisiting the utility of prenatal ultrasound in the routine workup of first febrile UTI: A systematic review and meta-analysis of the negative predictive value of prenatal ultrasound for identification of urinary tract abnormalities after first febrile urinary tract infection in children

CONTEXT

The current EAU/ESPU and recently retired AAP pediatric UTI guidelines recommend renal bladder ultrasound after first febrile UTI in children to screen for structural abnormalities, regardless of findings on prenatal ultrasound.

OBJECTIVE

Test the hypothesis that a normal prenatal ultrasound could rule out urinary tract abnormality on post-UTI ultrasound.

DATA SOURCES

Medline, Embase, Cochrane Library.

STUDY SELECTION

Studies including pediatric patients with first febrile UTI who had both prenatal and post-UTI ultrasound.

DATA EXTRACTION

Anatomical abnormalities detected by prenatal and post-UTI ultrasound as reported per individual study criteria were extracted. Meta-analyses of 9 studies (2981 patients) were performed using a random-effects model and composite estimates of the negative predictive value (NPV) of prenatal ultrasound were calculated.

RESULTS

Overall summary NPV of prenatal ultrasound for all pediatric patients was 77%, with heterogeneity score (I2) 97.9%. Summary NPV of prenatal ultrasound for all patients under two years of age was similar at 75%, with I2 98.2% For the 4 studies to which we could apply a more stringent definition of abnormality, summary NPV was 85% and I2 97.5% for prediction of moderate post-UTI ultrasound abnormalities and summary NPV was 93% and I2 90.4% for severe abnormalities.

DISCUSSION

While we calculated an 85% NPV for a normal prenatal ultrasound to rule out significant postnatal abnormality as defined within individual studies, substantial heterogeneity amongst publications limited the precision of our estimates. This highlights the need for more rigorous investigations with attention to timing of ultrasound and the application of clinically meaningful definitions for abnormal prenatal and post-UTI studies. This may allow judicious use of prenatal ultrasound to guide clinical management for children with first febrile UTI and minimize redundant imaging with potential for false positive results. Until then, the current guidelines are justified based on the limited and heterogenous data from the currently available published studies.

Correlation of Renal Scarring to Urinary Tract Infections and Vesicoureteral Reflux in Children

Objective

To study the association of the grade of vesicoureteral reflux (VUR) and urinary tract infections (UTI) with renal scarring at the first clinical presentation of patients who underwent antireflux surgery. Materials and methods. Between 2015 and 2020, 150 patients (194 units) who underwent antireflux surgery had dimercaptosuccinic acid (DMSA) renal scans preoperatively. Patients were classified into the nonscar and scar groups according to DMSA scan results. Moreover, cases were classified into afebrile UTI, febrile UTI, and antenatal hydronephrosis (ANH) according to the mode of presentation. We correlated the mode of presentation and the grade of VUR to the presence/absence of renal scars in both groups.

Results

The mean follow-up was 45 months preoperatively. The mode of presentation was afebrile, febrile UTIs, and antenatal hydronephrosis in (50, 14), (20, 46), and (10, 10) patients in the nonscar and scar groups, respectively. Of the 20 patients who presented ANH, 10 (50%) had scars. Clinical presentation was correlated to the presence of renal scarring and its degree. The scar group had significantly higher grades of VUR than the nonscar group (grades I–II (50 units versus 10 units), grade III (28 units versus 40 units), and grade IV–V (22 units versus 44 units) for the nonscar versus scar groups, respectively (pvalue <0.001).

Conclusion

Renal scarring is associated with higher grades of reflux and urinary tract infections. We advocate further research investigating infants who had UTIs with or without fever for early detection of reflux.

Is there a relationship between renal scarring and neutrophil-to-lymphocyte ratio in patients with vesicoureteral reflux?

OBJECTIVES

Vesicoureteral reflux (VUR) exacerbates the risk of renal scarring by establishing a ground for pyelonephritis. It is known that the inflammatory process is more influential than the direct damage caused by bacterial infection in the development of renal scars after pyelonephritis. Therefore, the present study aims to investigate the relationship between renal scarring and systemic inflammatory markers in patients with VUR.

MATERIAL AND METHODS

Hundred and ninety-two patients (116 females, 76 males) diagnosed with VUR were divided into two groups based on the presence or absence of renal scarring and into three groups according to the grade of VUR (low, moderate and high). Neutrophil count, lymphocyte count, mean platelet volume (MPV) and neutrophil-to-lymphocyte ratio (NLR) were compared among the groups.

RESULTS

Of the 192 patients, 102 had renal scarring. The age and gender distribution did not differ significantly between the groups with and without renal scarring (p > 0.05). However, the grade of reflux and lymphocyte count were significantly higher in the group with renal scarring (p < 0.05), and the NLR was significantly lower in the group with renal scarring (p < 0.05). The lymphocyte count was significantly higher (p < 0.05) and NLR was significantly lower in the high-grade VUR group (p < 0.05). However, MPV values did not differ significantly (p > 0.05) between the groups.

CONCLUSIONS

NLR can be used to predict renal scarring in patients with VUR, especially in the period of 3-6 months after the first attack of infection, and may even serve as a candidate marker for treatment selection. However, larger series and prospective studies are needed.

Effectiveness and risks of endoscopic management compared to vesicoureteral reimplantation in patients with high-grade vesicoureteral reflux: systematic review and network meta-analysis

The purpose of this study is to determine the effectiveness and safety of endoscopic management compared to ureterovesical reimplantation in pediatric patients with high-grade vesicoureteral reflux in terms of urinary tract infection. We performed a network meta-analysis. We searched in MEDLINE, EMBASE, LILACS, and CENTRAL. We included clinical experiments, quasi-experiments, and cohorts studies. The population was men and women between 1 month and 15 years old. Patients had primary high-grade VUR diagnosed by voiding cystourethrography. The interventions were subureteric bulking agent endoscopic injection (polytetrafluoroethylene, hyaluronic acid, collagen, Dx/Ha, and PPC) vs vesicoureteral reimplantation (Cohen, Politano-Leadbetter, Glenn-Anderson, and Lich-Gregoir), and the primary outcome was urinary infections. Nine studies accomplished the inclusion criteria (seven observational and two clinical experiments). A total of 1448 renal units underwent surgical treatments for the correction of high-grade VUR. Regarding the primary outcome, we compared Dx/Ha with Cohen, Lich-Gregoir, and PPC, finding an RD of -0.02 (95%CI -0.09 to 0.06), RD of -0.02 (95%CI -0.10 to 0.07), and an RD of -0.03 (- 0.13 to 0.07), respectively.Conclusion: Our study showed that there were no differences in UTI episodes after VUR correction in patients undergoing endoscopic management compared with vesicoureteral reimplantation. What is Known: • Primary vesicoureteral reflux is one of the most common congenital anomalies of the urinary tract. • The clinical practice guidelines recommend the surgical management of patients with high-grade VUR. What is New: • There were no differences in UTI episodes after VUR correction in patients undergoing endoscopic management compared with vesicoureteral reimplantation.

Is endothelial glycocalyx damage a cause of renal scarring in vesicoureteral reflux with febrile urinary tract infection?

INTRODUCTION

Endothelial glycocalyx is a luminal layer which can be damaged by inflammatory agents or pathogens. The endothelial glycocalyx damage is thought to have a role in the formation of renal scars in children who have febrile urinary tract infection and vesicoureteral reflux. This study aimed to compare the blood levels of endothelial glycocalyx components heparan sulfate and Syndecan-1 in children with and without renal scarring due to vesicoureteral reflux-associated febrile urinary tract infection.

MATERIALS AND METHODS

Data of the patients diagnosed with vesicoureteral reflux without renal scarring (Group 1), patients with vesicoureteral reflux and renal scarring (Group 2), and completely healthy children (Group 3) were retrospectively reviewed. Blood levels of heparan sulfate and Syndecan-1 were measured and the results were compared.

RESULTS

The entire cohort consisted of 90 patients; there were 30 patients in each group. Mean patient age was 49.7±18.0 months. Mean serum heparan sulfate (42.90±18.90 ng/mL) and Syndecan-1 (37.59±13.77 ng/mL) levels of Group 2 were significantly higher than those of other groups. The cut-off value for heparan sulfate was 35.17 ng/mL, with a 63% sensitivity and 86% specificity. The cut-off value for Syndecan-1 was 29.99 ng/mL with a 70% sensitivity and 80% specificity.

CONCLUSION

Our findings indicate that blood levels of heparan sulfate and Syndecan-1 could be related with renal scarring in patients with vesicoureteral reflux, especially in the setting of febrile urinary tract infection. However, due to their low sensitivity, these biomarkers should be used along with clinical data.

The risk factors for recurrence of febrile urinary tract infection and renal scarring in children with functional urinary incontinence

OBJECTIVES

Functional urinary incontinence is often associated with recurrent urinary tract infection (UTI), vesicoureteral reflux (VUR), and renal scarring. This study aims to evaluate the correlations between urodynamic findings and recurrence of UTI, VUR, and renal scarring in children with functional incontinence.

METHODS

In this retrospective observational study, data on the presence of VUR, urodynamics and 99Tc-dimercaptosuccinic acid scintigraphy findings, and episodes of febrile UTI were obtained from patients' records. The patients had at least 3 years of follow-up.

RESULTS

There were significant associations between recurrence of UTI and decreased bladder capacity (hazard ratio: 1.321, P = .028). The receiver operator characteristic curve analysis showed a cutoff value for compliance of 13.25 mL/cmH₂ O for renal scarring (P = .000). There was a significant association between bladder wall thickening and VUR (odds ratio: 2.311, P = .008). The compliance had a cutoff value of 14.7 mL/cm H₂ O (P = .023) for severe VUR. The frequency of renal scarring was higher in patients with severe VUR and dysfunctional voiding (P = .001 and P = .041, respectively). The independent risk factors for renal scarring were low compliance, severe VUR, and dysfunctional voiding in children with functional incontinence, but recurrence of febrile UTI was not a risk factor for renal scarring. Decreased bladder capacity was a risk factor for recurrence of febrile UTI.

CONCLUSIONS

The present study suggests that low compliance, severe VUR, and dysfunctional voiding, but not the recurrence of febrile UTI, are the independent risk factors for renal scarring in children with functional incontinence, and decreased bladder capacity is the risk factor for the recurrence of febrile UTI.

Renal scarring following urinary tract infections in children

Urinary tract infection (UTI) is the most common bacterial infection seen in younger age group children. The most common risk factor for renal scarring in children with post-UTI is vesicoureteral reflux (VUR). This study looked at renal scarring following UTI in children by dimercaptosuccinic acid (DMSA) scan. It is a cross-sectional time bound study done among 40 infants and children with UTI for a period of 24 months. Their clinical presentation and laboratory data, including micturating cystourethrogram, were documented. DMSA scan, done during the follow-up, established the presence of renal scars if any. UTI was more common in males. Children with history of recurrent UTI had renal scarring. Statistical significance was noted when first and recurrent attacks of UTI were compared for clinical and diagnostic characteristics like Escherichia coli UTI (p = 0.007), increasing grades of VUR (p = 0.006) and renal scar formation (p = 0.041). The study concluded that the high grades of antenatal hydroureteronephrosis (100%), febrile UTI (34%), younger age group (67.5%) and E. coli UTI (86%) were more associated with recurrent attacks of UTI and renal scarring. DMSA, being the non-invasive test, is better proven to be an investigation of choice than other invasive modalities for follow-up of children with recurrent attacks of UTI.

The impact of obesity on febrile urinary tract infection and renal scarring in children with vesicoureteral reflux

INTRODUCTION

It has become clear that obesity is associated with a variety of infectious diseases, including urinary tract infection (UTI) and renal scarring.

OBJECTIVE

The aim of this study was to evaluate the association between obesity and the degree of febrile UTI (fUTI) and renal scarring in children with vesicoureteral reflux (VUR), and to stratify the results into obesity subcategories.

STUDY DESIGN

A total of 186 patients were diagnosed with VUR between January 2002 and December 2008. This study retrospectively reviewed the medical records of 72 children with primary VUR who had recurrent fUTI (more than twice). Overweight or obese status of the patients aged <2 years was defined using weight-for-length (WFL) measurements. For 2-5 year old children, body mass index (BMI) percentile-for-age was used. They were divided into three groups as follows; standard (<85%), overweight (85-95%), and obese (≥95%). The following clinical variables were compared: age at diagnosis of primary VUR (months), sex, VUR grade, hydronephrosis grade, presence of renal scarring, surgical treatment, and degree of inflammation during fUTI.

RESULTS

In the overweight and obese groups, VUR was diagnosed at a young age (P = 0.05), the degree of renal scarring was more severe (P = 0.006), and serum white blood cell count, C-reactive protein, and erythrocyte sedimentation rate (ESR) levels were significantly higher (P < 0.001, P < 0.001, and P < 0.001, respectively). Abnormal focal dimercaptosuccinic acid (DMSA) defects were present in 25 of the 72 children (35%). Cortical defects occurred more frequently in children with obesity, and they were associated with a higher grade of reflux and serum ESR levels (P = 0.007, P = 0.042, and P = 0.021, respectively). Among these risk factors, high-grade VUR (OR = 9.93, 95% CI = 1.13-86.71), and being overweight and obese (OR = 5.26, 95% CI = 1.75-15.82) were associated with increased renal scarring. However, ESR was not associated with renal scarring (OR = 1.01, 95% CI = 0.95-1.07).

DISCUSSION

The relationships between obesity and UTI are controversial. Some studies have shown positive results; however, other studies have shown opposite results. The main limitations of this study were the retrospective data collection via electronic medical records, and the small number of subjects.

CONCLUSIONS

This study showed that obesity in patients with VUR has an effect on fUTI and renal scar formation. If the patients with VUR have obesity, close follow-up should be performed, and VUR patients should be started on a weight-loss program, which could reduce the number of patients with chronic kidney disease in the future.

Accuracy of early DMSA scan for VUR in young children with febrile UTI

OBJECTIVE

To evaluate the accuracy of an acute (99m)Tc-dimercaptosuccinic acid (DMSA) scan in predicting dilating vesicoureteral reflux (VUR) among young children with a febrile urinary tract infection (UTI).

METHODS

The medical records of children (≤ 2 years of age), presenting with febrile UTI between January 2000 and December 2011, were retrospectively reviewed.

RESULTS

A total of 523 children were included in this study, of whom 397 children (75.9%) had abnormal DMSA results and 178 children (34.0%) were identified as VUR on micturating cystourethrography (MCU). Among all the patients, the number of children with dilating VUR was 151 (28.9%). The rate of abnormal results on DMSA for the dilating VUR group was significantly higher than the rates for the non-VUR and low-grade VUR groups (P < .01). In the <6 months age group and ≥ 6 months age group, the sensitivities of DMSA in predicting dilating VUR were 96.15% and 100.0%, respectively, the negative predictive values were 97.26% and 100.0%, respectively, and the negative likelihood ratios were 0.0911 and 0.0000, respectively.

CONCLUSION

For children ≤ 2 years of age with a febrile UTI, an acute DMSA scan is valuable in the exclusion of dilating VUR. The likelihood of the presence of dilating VUR on MCU is rather low when the result of DMSA is negative. DMSA should be conducted to assess the need for an MCU.

Prevalence and predictors of renal functional abnormalities of high grade vesicoureteral reflux

PURPOSE

The association of vesicoureteral reflux, febrile urinary tract infections and renal parenchymal damage is well recognized. We determined the prevalence and predictors of renal functional abnormalities in children with high grade vesicoureteral reflux.

MATERIALS AND METHODS

We retrospectively reviewed the medical records and dimercapto-succinic acid scans of 774 consecutive children with primary high grade vesicoureteral reflux (grade IV-V) seen at our institution between 1998 and 2011. For multivariate analysis we analyzed variables associated with renal functional abnormalities, such as presentation history, age, gender and reflux grade, in a logistic regression model.

RESULTS

Of the children 698 (90%) and 76 (10%) had grade IV and V reflux, respectively. Dimercapto-succinic acid scans revealed renal functional abnormalities in 291 children (37.6%), including 240 (34%) with grade IV and 51 (67%) with grade V reflux. Univariate analysis showed that age greater than 1 year (OR 2.95, p <0.001), grade V reflux (OR 4.09, p <0.001) and preoperative bladder/bowel dysfunction (OR 2.94, p = 0.026) were significant predictors of renal functional abnormalities. Multivariate analysis showed that age greater than 1 year (OR 3.45, p = 0.001) and grade V reflux (OR 5.89, p <0.001) were the most significant independent predictors of such abnormalities.

CONCLUSIONS

There is an increased risk of renal functional abnormalities in children older than 1 year and those with grade V vesicoureteral reflux. Patients with a history of bladder/bowel dysfunction are also at greater risk for such abnormalities. The early detection and treatment of high grade vesicoureteral reflux may prevent acquired renal parenchymal damage and limit the progression of renal damage in patients with congenital reflux nephropathy.

Predict the spontaneous resolution of vesicoureteral reflux by direct radionuclide cystography

OBJECTIVES

To evaluate the prognostic value of initial direct radionuclide cystography (DRC) for spontaneous resolution of vesicoureteral reflux (VUR).

METHODS

Fifty-one children with initial diagnosis and 1-6 years' follow-up of VUR by DRC were enrolled in this study. VUR was graded according to the anatomic grading as (1) mild reflux corresponding to tracer just in ureter, (2) moderate reflux with accumulation of activity in a non-dilated collecting system and ureter, and (3) severe reflux equated with a dilated ureter and collecting system. The severity of VUR was also expressed according to the functional classification as (1) transient reflux, which occurred at filling or voiding phase only and (2) persistent reflux, present in both filling and voiding phases.

RESULTS

Twenty-nine of the 51 children had unilateral VUR, and the other 22 had bilateral VUR. In the total of 73 refluxing ureters, there were 12 mild, 49 moderate and 12 severe VUR according to anatomic grading, and 30 transient and 43 persistent VUR according to the functional grading. After follow-up, resolution of VUR was found in 92% (11/12) of mild, 59% (29/49) of moderate and 25% (3/12) of severe VUR (P=.04, mild vs. moderate; P=.003, mild vs. severe). Eighty percent (24/30) of transient and 44% (19/43) of persistent reflux showed spontaneous resolution (P=.003).

CONCLUSIONS

DRC allows anatomic and functional classification of VUR. It is an ideal method for the diagnosis, staging and follow-up of VUR, and provides valuable information to predict the patient's outcome.

Renal scar formation after urinary tract infection in children

Urinary tract infection (UTI) is a common bacterial illness in children. Acute pyelonephritis in children may lead to renal scarring with the risk of later hypertension, preeclampsia during pregnancy, proteinuria, and renal insufficiency. Until now, vesicoureteral reflux (VUR) has been considered the most important risk factor for post-UTI renal scar formation in children. VUR predisposes children with UTI to pyelonephritis, and both are associated with renal scarring. However, reflux nephropathy is not always acquired; rather, it reflects reflux-associated congenital dysplastic kidneys. The viewpoint that chronic kidney disease results from renal maldevelopment-associated VUR has led to questioning the utility of any regimen directed at identifying or treating VUR. Despite the recognition that underlying renal anomalies may be the cause of renal scarring that was previously attributed to infection, the prevention of renal scarring remains the goal of all therapies for childhood UTI. Therefore, children at high risk of renal scar formation after UTI should be treated and investigated until a large clinical study and basic research give us more information.

Quality of life in children with vesicoureteral reflux

Vesicoureteral reflux (VUR) is commonly diagnosed in children presenting with urinary tract infections. Antibiotic prophylaxis and ureteric surgery are standard treatments for these children. Our aim was to investigate whether health-related quality of life (HRQOL) was altered in children treated for VUR. Children aged 1-5 years with grade III or higher VUR were identified through electronic records at the Stollery Children's Hospital. Parents of these children were mailed the TNO-AZL Netherlands Organisation for Applied Scientific Research Academic Medical Centre Quality of Life (TAPQOL) questionnaire. QOL scores for this group were compared with normative controls from the instrument's creators using the Mann-Whitney U test. Thirty-two of the 96 (33%) mailed surveys were returned. Eight children had surgery, and 19 were treated with antibiotic prophylaxis. When comparing the VUR group with the control group, we found that anxiety and social functioning scores were significantly better in patients with VUR (p < 0.01). The VUR group had worse scores in problem behavior, stomach complaints ,and communication (p < 0.01). This study reveals that children with VUR have a reasonable QOL when compared with controls. However, the diagnosis of VUR and its management does have an impact on gastrointestinal complaints, behavior, and communication, which may occur as a result of chronic medical intervention.

Urinary proteome analysis to exclude severe vesicoureteral reflux

OBJECTIVES

High-grade vesicoureteral reflux (VUR, grade IV or V) is a risk factor for renal scarring, impaired renal function, and arterial hypertension. Voiding cystourethrography is the gold standard for detecting the severity of VUR. High-grade VUR is present in the minority of children with urinary tract infection (UTI), thus exposing the majority to invasive diagnostics that have no surgical consequence. We therefore aimed at establishing a noninvasive test to identify children with high-grade VUR.

METHODS

In a case-control study, a specific urinary proteome pattern was established by capillary electrophoresis coupled to mass spectrometry in 18 patients with primary VUR grade IV or V, distinguishing these from 19 patients without VUR after UTI. This proteome pattern was independently validated in a blinded cohort of 17 patients with VUR grade IV or V and 19 patients without VUR.

RESULTS

Sensitivity in detecting VUR grade IV or V in the blinded study was 88%, specificity was 79%. The test's accuracy was independent of age, gender, and grade of VUR in the contralateral kidney. The odds ratio of suffering from VUR grade IV or V when tested positive was 28 (95% confidence interval: 4.5 to 176.0).

CONCLUSIONS

This noninvasive test is ready for prospective validation in large cohorts with the aim of identifying those children with UTI and hydronephrosis in need of further invasive diagnostics, such as voiding cystourethrography, thus sparing most children without pathologic urinary proteome patterns from additional diagnostics.

Acute phase 99mTc-dimercaptosuccinic acid scan in infants with first episode of febrile urinary tract infection

BACKGROUND

99mTc-dimercaptosuccinic acid (DMSA) scan is the golden standard for the diagnosis of acute pyelonephritis and renal scaring. We investigated the use of acute phase DMSA scan in infants presented promptly to the hospital because of the first episode of their febrile urinary tract infection (UTI).

METHODS

Ninety-eight infants with microbiologically confirmed first episode of febrile UTI were studied. DMSA scans were carried out within 7 days in these infants after admission. Infants with an abnormal acute DMSA scan underwent a second DMSA scan 6-12 months later.

RESULTS

Overall, acute DMSA scan was abnormal in 16 (16.3%) of the 98 patients. There were no differences in sex, age, fever over 38.5°C, blood inflammation indices, or evidence of vesicoureteral reflux (VUR) between patients with normal and abnormal acute DMSA scan (P>0.05). However, infants with grade III to V VUR as well as those with delayed treatment presented significantly increased renal involvement by acute DMSA scan (P<0.05). The sensitivity and specificity of abnormal acute DMSA scan to predict grade III to V VUR were 50% and 88% respectively. Its positive and negative likelihood ratios were 4.16 and 0.57, respectively. Of 16 children with abnormal initial DMSA scan results, 14 underwent a second DMSA scan. Follow-up DMSA scans were normal in 12 of the 14 children.

CONCLUSIONS

Parenchymal damage found in a minority of infants with febrile UTI presented promptly to the hospital. Acute phase DMSA scan should be carried out only in selected patients. An abnormal acute DMSA scan is a moderate predictor for dilated VUR and its ability to exclude VUR is restricted.

Risk factors for renal scar formation in infants with first episode of acute pyelonephritis: a prospective clinical study

PURPOSE

We prospectively determined the risk factors for renal scar formation after the first episode of acute pyelonephritis as confirmed on dimercapto-succinic acid scintigraphy in children younger than 1 year.

MATERIALS AND METHODS

A total of 213 infants with acute pyelonephritis were enrolled in the study. Infants with urological abnormalities other than vesicoureteral reflux were excluded from analysis. Followup scanning was performed 6 months after acute pyelonephritis and voiding cystourethrography was performed after the acute phase of infection. Possible risk factors were evaluated including gender, peak fever, duration of fever before and after treatment with antibiotics, white blood cell count, C-reactive protein concentration, presence of vesicoureteral reflux and reflux grade.

RESULTS

Six months after acute pyelonephritis 37 of 213 (17.4%) infants and 41 of 248 (16.5%) renal units with acute photon defects on initial dimercapto-succinic acid scintigraphy had renal scars. The rates of scar formation were significantly higher in infants with vesicoureteral reflux than in those without (39.4% vs 7.5%, p <0.001, OR 9.433) and in renal units with vesicoureteral reflux than in those without (39.4% vs 8.2%, p <0.001, OR 7.237). Renal scar formation was related to reflux grade (none-8.2%, grade I-20%, grade II-22.7%, grade III-40%, grade IV-70%, grade V-55.6%, p <0.001) but not to any other clinical or laboratory variables.

CONCLUSIONS

The presence of vesicoureteral reflux was the only independent risk factor for renal scar formation after acute pyelonephritis in infants. The prevalence of renal scarring was significantly correlated with reflux grade. Voiding cystourethrography is necessary in infants after the first acute pyelonephritis episode is confirmed on dimercapto-succinic acid renal scintigraphy.

Risk factors for recurrent urinary tract infection in infants with vesicoureteral reflux during prophylactic treatment: effect of delayed contrast passage on voiding cystourethrogram

OBJECTIVES

To investigate the risk factors for recurrent urinary tract infection (UTI) in infants with vesicoureteral reflux (VUR) because little is known regarding the risk factors for breakthrough infection.

METHODS

We compared children with infantile VUR with (20 boys, mean age 2.7 months) and without (20 boys and 4 girls, mean age 4.7 months) recurrent UTI. The factors compared included sex, timing of UTI episode, degree and bilaterality of the reflux, hydronephrosis, renal scar, associated congenital anomalies, voiding dysfunction, and delayed ureteral excretion of refluxed contrast on the voiding cystourethrogram.

RESULTS

Univariate Cox survival-time regression analysis showed that a younger mean age at the first UTI, bilateral reflux, and grade 4-5 VUR and hydronephrosis on the initial ultrasound scan significantly increased the risk of recurrent UTI (P<.05 each). On multivariate analysis, high-grade (P=.009) and bilateral (P=.016) VUR were independently associated with an increased risk of recurrent UTI. Of the infants with and without recurrent UTI, 80% and 0%, respectively, presented with high-grade VUR, as shown by delayed contrast passage on the voiding cystourethrogram. A urodynamic study of 11 infants with recurrent UTI showed decreased bladder capacity in 2 infants and a larger residual volume in 1 infant.

CONCLUSIONS

During the first year after birth, high-grade and bilateral VUR significantly increased the risk of recurrent UTI. Delayed contrast passage on the voiding cystourethrogram was significantly associated with an increased risk of recurrent UTI.