First UTI in Febrile Infants: No Ideal Workup Exists

In febrile infants with a first urinary tract infection (UTI), an aggressive diagnostic protocol is very sensitive for vesicoureteral reflux (VUR) and scarring but has high financial and radiation costs, according to a study published online February 25 in Pediatrics.

"The core imaging modalities advocated after a UTI have been ultrasonography, voiding cystourethrography (VCUG), and technetium⁹⁹dimercaptosuccinic acid (DMSA) scan renal scintigraphy," write Claudio La Scola, MD, from the Nephrology and Dialysis Unit, Department of Pediatrics, Azienda Ospedaliero-Universitaria "Sant'Orsola-Malpighi," Bologna, Italy, and colleagues. "The reason for imaging is to detect obstructive malformations, VUR, and renal parenchymal damage; however, there is no consensus as to the nature of the malformations, severity of reflux, or degree of damage that warrants detection. Whereas an intensive approach was recommended by some, there has been a proliferation of guidelines that have proposed different diagnostic algorithms, with the expectation of minimizing invasive procedures while maintaining an acceptable sensitivity and specificity for the detection of abnormalities."

The study goal was to compare the yield, economic, and radiation costs of 5 diagnostic algorithms: Melbourne Royal Children's Hospital, National Institute of Clinical Excellence (NICE), top-down approach, American Academy of Pediatrics (AAP), and Italian Society of Pediatric Nephrology. The reference standard was a protocol using all 3 tests (ultrasonography, cystography, and late technetium⁹⁹ DMSA scan) after a first febrile UTI.

Participants were 304 children with first febrile UTI who were enrolled in the randomized controlled Italian Renal Infection Study 1 (IRIS1). All participants, aged 2 to 36 months, had completed the 3 diagnostic tests. In a retrospective simulation, the investigators applied the 5 different guidelines to determine the diagnostic yield of abnormal test results, as well as economic and radiation costs as secondary outcomes.

No Perfect Protocol

Nearly one quarter (22%) of children had VUR, and 15% had parenchymal scarring. Of the 5 protocols, the top-down approach was the most sensitive for detecting VUR (76%) and scarring (100%) but also had the highest economic (€52,268) and radiation costs (624 mSv).

NICE and AAP were the most specific protocols for VUR (90%), and the Italian Society of Pediatric Nephrology was the most specific for scarring (86%). Financial cost would have been the lowest for NICE (€26,838), and radiation exposure would have been the lowest for AAP (42 mSv).

"There is no ideal diagnostic protocol following a first febrile [UTI]," the study authors write. "An aggressive protocol has a high sensitivity for detecting VUR and scarring but carries high financial and radiation costs with questionable benefit."

Limitations of this study include issues with selection criteria for the IRIS1. In addition, the investigators performed the simulation of diagnostic algorithms at the time of the first UTI, not considering children who would have had a second UTI.

"This study may be useful in helping the practicing clinician decide which algorithm is most applicable for any given patient and family, considering multiple variables: socioeconomic, cultural, and geographical," the study authors conclude.

The study received no external funding. The study authors have disclosed no relevant financial relationships.

Pediatrics. Published online February 25, 2013. Abstract