Febrile UTI: Early Treatment Lowers Risk for Renal Scarring

Jennifer Garcia

July 29, 2016

Delaying initiation of antibiotic therapy in children with febrile urinary tract infections (UTIs) may contribute to renal scarring, according to a new retrospective cohort study published online July 25 in JAMA Pediatrics.

Researchers evaluated data for 482 children (age, 2 - 72 months) from two previous longitudinal studies that followed children presenting for first or second UTI. Overall, 78% of included children had a diagnosis of vesicoureteral reflux, which has been shown to increase the risk for UTI. At the time of enrollment, clinicians asked parents the duration of their child's fever (in hours) before initiation of antibiotic therapy. A Tc 99m dimercaptosuccinic acid (DMSA) scan was evaluated at baseline and again at the 24-month follow up or 3 to 4 months after withdrawal from the study. The researchers defined new renal scarring "as the presence of areas of photopenia plus contour changes on a late DMSA scan that were not present on the baseline scan." The investigators excluded children with no DMSA scan, no fever, and/or missing data from the study.

The study authors found that overall, 35 (7.2%) children had evidence of new renal scarring on the outcome DMSA scan and noted an association between renal scarring and initiation of antibiotic therapy. The median duration of fever in children with renal scarring was 72 hours compared with 48 hours among children with no renal scarring (P = .003). This association remained even after adjusting for factors such as age, ethnicity, history of urinary tract infection, and infecting organism.

"After adjusting other covariates, we estimate that a delay of 48 hours or more would increase the odds of new renal scarring by about 47%," write Nader Shaikh, MD, MPH, from the Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pennsylvania, and colleagues.

The authors note that these findings concur with previous study findings in similar patient populations and "strongly support the hypothesis that delay in the initiation of antimicrobial therapy and the development of renal scars are related."

The researchers acknowledge limitations in the study. For example, parental recollection about the duration of fever before antibiotic therapy may have been imprecise, and the number of children found to have new renal scarring was low overall.

In an accompanying editorial, Lucila Marquez, MD, MPH, and Debra L. Palazzi, MD, MEd, from the Baylor College of Medicine and Texas Children's Hospital, Houston, write: "While this study provides further evidence for timely treatment of suspected UTI, the reality is that practitioners will continue to be challenged by the need to discern which patients are at risk and who warrants testing."

Dr Marquez and Dr Palazzi underscore that one of the challenges is that clinical prediction rules currently use the duration of fever as a criterion for assessing the patient's risk for UTI, suggesting this may result in delayed diagnosis and intervention.

The editorialists agree, however, that the findings in the present study may help educate clinicians and caregivers on the importance of timely evaluation of febrile illness, particularly in children with an increased risk for or history of UTI.

Funding for this study was provided through grants from the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. The authors and editorialists have disclosed no relevant financial relationships.

JAMA Pediatrics. Published online July 25, 2016. Article full text, Editorial full text

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