Negative Urinalyses in Febrile Infants Age 7 to 60 Days Treated for Urinary Tract Infection
The role of the urinalysis (UA) in the management of young, febrile infants is controversial. To assess how frequently infants are treated for urinary tract infection (UTI) despite having normal UA values and to compare the characteristics of infants treated for UTI who have positive versus negative UAs, we reviewed 20,570 well-appearing febrile infants 7-60 days of age evaluated at 124 hospitals in the United States who were included in a national quality improvement project. Of 19,922 infants without bacteremia and meningitis, 2,407 (12.1%) were treated for UTI, of whom 2,298 (95.5%) had an initial UA performed. UAs were negative in 337/2,298 (14.7%) treated subjects. The proportion of infants treated for UTI with negative UAs ranged from 0%-35% across hospitals. UA-negative subjects were more likely to have respiratory symptoms and less likely to have abnormal inflammatory markers than UA+ subjects, indicating that they are mounting less of an inflammatory response to their underlying illness and/or might have contaminated specimens or asymptomatic bacteriuria.
© 2019 Society of Hospital Medicine
The sensitivity of the urinalysis (UA) in young infants has been reported to be in the 75% to 85% range.1-4 This suboptimal sensitivity has prevented a widespread adoption of the UA as a true screening test for urinary tract infection (UTI). Although infants with a positive urine culture and a negative UA may have asymptomatic bacteriuria (AB) or contamination,5-7 they are often treated for UTI.
Due to these concerns, the American Academy of Pediatrics (AAP) recommended in their 2011 UTI Practice Guidelines that UA criteria should be incorporated into the definition of UTI.1 However, these guidelines were intended for the 2-24 month age range, leaving a gap in our understanding of the appropriate management of infants <2 months. It is unknown how UA results influence the current management of UTI in young, febrile infants. Using data from a large, nationally representative quality improvement project surrounding the management of febrile infants, this investigation aimed to examine how frequently infants are treated for UTI despite having normal UAs and to determine whether infant and hospital characteristics are different in infants treated for UTI with a positive UA as compared to those treated for UTI with a negative UA.
METHODS
Subjects and Setting
This is a secondary analysis of the AAP’s Reducing Excessive Variability in the Infant Sepsis Evaluation (REVISE) project that involved 20,570 well-appearing infants 7-60 days of age evaluated in the emergency department and/or inpatient setting for fever ≥38◦C without a source between September 2015 and November 2017 at 124 community- and university-based hospitals in the United States. Data were collected via chart review and entered into a standardized tool for the project. This project was deemed exempt by the AAP Institutional Review Board. Because all data were de-identified, some sites did not require Institutional Review Board approval while others required data sharing agreements.
Variables and Definitions
A positive UA was defined as having any leukocyte esterase, positive nitrites, or >5 white blood cells (WBCs) per high power field. Treatment for UTI was defined using the question “Did the urine culture grow an organism that was treated as a pathogen with a full course of antibiotics?” Subjects treated for meningitis or bacteremia were excluded in order to focus on uncomplicated UTI. “Abnormal inflammatory markers” were defined as having a WBC count <5,000 or >15,000 cells/mm3, an absolute band count ≥ 1,500 cells/mm3, a band to neutrophil ratio of >0.2, cerebrospinal fluid (CSF) WBC count of >8/mm3, a positive CSF gram stain, or an elevated C-reactive protein or procalcitonin level, as defined by the institutional range. Although technically not an “inflammatory marker,” CSF gram stain was included in this composite variable because in the rare cases that it is positive, the result would likely influence risk stratification and immediate management. Infants’ ages were categorized as either 7-30 days or 31-60 days. Hospital length-of-stay (LOS) was recorded to the nearest hour and infants who were not hospitalized were assigned a LOS of 0 hours. Hospital characteristics were determined through a survey completed by site leads.
