Risk Factors for UTI Recurrence and Renal Scarring in Kids

Veronica Hackethal, MD

June 08, 2015

Bladder and bowel dysfunction (BBD) and vesicoureteral reflux (VUR) may be risk factors for recurrent urinary tract infection (UTI) in children, especially when both problems occur simultaneously, according to a study published online June 8 in Pediatrics.

The results could help providers identify children at risk for recurrent UTI who might benefit from preventive treatment.

"[C]linicians must help families decide whether the benefits of prophylaxis outweigh the risks and inconvenience," Ron Keren, MD, MPH, from the Children's Hospital of Philadelphia, Pennsylvania, and colleagues write.

"Prophylaxis may be particularly effective in children while they are being treated for BBD, and it is important to prevent UTI recurrences, which can interfere with bowel and bladder retraining," they add.

Retrograde urine flow, or VUR, is a known risk factor for recurrent UTIs. VUR occurs in 30% to 40% of children who have had a UTI and is also linked to renal scarring. Bladder and bowel dysfunction may also predispose to recurrent UTI and refers to problems filling or emptying the bladder and abnormal bowel patterns including constipation and encopresis. Symptoms include urinary frequency, urgency, incontinence, increased time between urination, constipation, and stool soiling.

The 2-year multisite study enrolled children from diverse settings. Participating children had had one or two febrile or symptomatic UTIs, for which they did not receive antibiotic prophylaxis. The study included 305 children between the ages of 2 and 71 months with diagnoses of VUR and who received placebo as part of the RIVUR (Randomized Intervention for Vesicoureteral Reflux) study, which occurred from 2007 to 2011. The study also included 195 children without VUR who were part of the CUTIE (Careful Urinary Tract Infection Evaluation) study. Children in the CUTIE study had been screened for the RIVUR study but were not included because they did not have VUR.

Children with VUR had higher rates of UTI recurrence after 2 years compared with children without VUR (Kaplan-Meier estimate, 25.4% vs 17.3%, respectively; adjusted HR: 1.58; 95% confidence interval, 1.04 - 2.42). The rate of recurrent febrile or symptomatic UTI was highest in those with grade III or IV VUR (Kaplan-Meier estimate, 28.9%).

Children with BBD and renal scarring at baseline also had increased risk for recurrent UTI (adjusted hazard ratio, 2.07 [95% confidence interval, 1.09 - 3.93]; and adjusted hazard ratio, 2.88 [95% confidence interval, 1.22 - 6.80], respectively).

Children with both BBD and VUR had the highest risk for recurrent UTI (56%), followed by children with BBD but without VUR (35%) and children with no BBD and grade 0 to II VUR (29%).

After 2 years, 5.6% (n = 8) of children without VUR and 10.2% (n = 24) with VUR had renal scars, but the difference did not reach statistical significance.

After diagnosis of BBD, some study sites advised families about how to manage the condition, which could have reduced rates of recurrent UTIs. As a result, the study could have underestimated recurrence rates. Small sample size in the VUR group and low rates of renal scarring could also have interfered with the identification of other risk factors and differences between groups.

Strategies for preventing recurrent febrile or symptomatic UTI include treatment of BBD and antimicrobial prophylaxis, the authors write.

"Given the increasing concerns regarding the contribution of antimicrobial prophylaxis to the emergence of bacterial resistance and the unknown impact on the microbiome, more accurate risk stratification will permit more judicious use of antimicrobial prophylaxis in the future," they conclude. "Before risk stratification strategies can be used to selectively identify patients for antimicrobial prophylaxis, additional research is needed to validate the risk factors and profiles that we identified."

The authors have disclosed no relevant financial relationships.

Pediatrics. Published online June 8, 2015. Abstract

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