There is no one perfect diagnostic algorithm for children with a first uncomplicated febrile urinary tract infection, according to a retrospective cohort simulation comparing six diagnostic approaches for yield, cost, and radiation dose.
Five diagnostic algorithms possibly using ultrasound, voiding cystourethrography (VCUG), and late technetium99 dimercaptosuccinic acid (DMSA) scan renal scintigraphy, plus an "all tests performed" protocol were retrospectively simulated using data from 304 children aged 2-36 months with a first uncomplicated febrile UTI who had participated in an earlier multicenter trial.
While the National Institute of Clinical Excellence (NICE 2007) and American Academy of Pediatrics (AAP 2011) algorithms had the highest specificities for vesicoureteral reflux (91% and 90% respectively), the Italian Society of Pediatric Nephrology (ISPN 2011) had the highest specificity for scars (86%), according to Dr. Claudio La Scola and colleagues. The report was published online in the Feb. 25 issue of Pediatrics (2013;131:e665–71 [doi:10.1542/peds.2012-0164]).
The "top down approach" (TDA 2007) had the highest sensitivity for detecting vesicoureteral reflux (VUR) (76%) and scarring (100%), but also was the most costly financially (52,268 euros) and in radiation dose (624 mSv). The study also evaluated the Royal Children’s Hospital of Melbourne algorithm (RCH 2006).
"An aggressive protocol has a high sensitivity for detecting abnormalities, which in some cases could be of questionable benefit to the infants, and it is burdened with high financial and radiation costs," wrote Dr. La Scola of Azienda Ospedaliero-Universitaria, Bologna, Italy, and his coauthors.
Researchers found that the NICE approach would have been the least costly (26,838 euros), and the AAP algorithm would have resulted in the lowest radiation exposure (42 mSv).
The primary outcomes of the study were the yield of abnormal tests – all grades of reflux, grades III-V reflux, and UTI related renal scarring, with secondary outcomes of total costs and total radiation dose.
"Whereas the all tests protocol would perform ultrasonography, VCUG, and DMSA scan in all children and would not miss any reflux or scar, the five guidelines formulated algorithms with the aim of identifying a high-risk population for VUR or scarring," Dr. La Scola and colleagues reported. "All five selective protocols missed a variable proportion of reflux and scars (with the exception of the TDA protocol, which detected 100% of the scars), and none would have diagnosed all the nephrourologic abnormalities."
When it came to detecting reflux grades I-V and III-V, the TDA, which uses the acute DMSA scan result as its first step, showed the highest sensitivity (76% and 85% respectively) and negative predictive value (89% and 97% respectively) but low specificity (54% and 50%).
The other four diagnostic algorithms all use the results of ultrasonography, with or without the presence of risk factors, as their first step.
"This approach would fail to detect all children with reflux, because it is well known that ultrasonography, after an initial febrile UTI, is not able to reliably identify changes associated with reflux or subsequent renal damage," the researchers reported.
The researchers suggested that a less aggressive diagnostic approach to uncomplicated febrile UTI is becoming more popular, with growing awareness that acquired pyelonephritic scarring is less of a contributor to renal damage than previously thought.
None of the authors had any financial disclosures and the study received no external funding.