Abnormal Scan After UTI Raises Kids' Risk for Renal Scarring

Diedtra Henderson

August 04, 2014

An abnormal renal ultrasonographic finding alone or in tandem with a fever of at least 39°C and an etiologic organism other than Escherichia coli are warning signs that children with a urinary tract infection (UTI) are at twice the risk of developing renal scarring.

Nader Shaikh, MD, MPH, from the Division of General Academic Pediatrics, Children's Hospital of Pittsburgh, Pennsylvania, and colleagues report their findings in an article published online August 4 in JAMA Pediatrics.

According to Dr. Shaikh and coauthors, UTIs are the most common serious bacterial infection among children, with 10% to 15% of infections resulting in permanent renal scarring. A cascade of events that begin in childhood can lead to substantial scarring, reduced kidney function, and sometimes, end-stage renal disease as adults. The researchers sought to characterize prognostic risk factors for renal scarring among children and to create a prediction model that could be used by clinicians.

The authors extracted individual patient data from 9 published cohort studies of children aged 18 years or younger who had undergone renal scanning at least 5 months after their first UTI. Of the 1280 children who were included in their meta-analysis, 199 (15.5%) had renal scarring, and 100 of these patients (50.3%) had vesicoureteral reflux (VUR).

"Children with a model 1 score of 2 or more (21.7% of the sample) represent a high-risk group in whom the risk for renal scarring is twice the baseline risk," Dr. Shaikh and colleagues write. "These children (1) have an abnormal renal ultrasonographic finding or (2) have a temperature of at least 39°C and an etiologic organism other than E coli." According to the researchers, the presence of grade IV or V VUR was the most important risk factor for developing scarring. That occurred only in a small fraction of the children, however.

"[A]lthough our data confirm the importance of high-grade VUR as a risk factor for renal scarring, they do not resolve the difficult question of how to identify this important but small subgroup of children without subjecting all children to a [voiding cystourethrogram]," the authors add.

A half century ago, a link was hypothesized between UTI in childhood and renal damage leading to diseases in adulthood, such as hypertension and end-stage renal disease, according to an accompanying editorial. In the intervening years, researchers have been chasing tantalizing, but ultimately false, leads.

"Shaikh et al shift the focus from VUR to renal scarring and confirm the value of the [renal-bladder ultrasonogram] as a predictor of renal damage," writes Kenneth B. Roberts, MD, from the University of North Carolina School of Medicine, Chapel Hill, and Cone Health, Greensboro, in the editorial. "High fever and organisms other than Escherichia coli are also predictors, but notably, adding a [voiding cystourethrogram] and serum inflammatory markers to the evaluation contributes very little."

Dr. Roberts also lauded previous research teams for providing individual patient data: "This is an example of admirable collaboration among researchers, with clinicians and their patients the beneficiaries," he writes.

"Early identification of children at risk for renal scarring using the prediction rules developed in this study could help clinicians deliver specific treatment and follow-up for this small subgroup in the future," the study authors conclude.

"We are hopeful that data from this study, along with emerging data from longitudinal and biomarker studies, can be used to develop individualized care plans for children with a first UTI."

The study authors and the commentator have disclosed no relevant financial relationships.

JAMA Pediatr. Published August 4, 2014. Abstract

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