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Clinical rule based on symptoms increases chance of identifying UTI

A clinical rule based on symptoms and signs of urinary tract infections should be used to enhance the current clinical practice of identifying young children for noninvasive urine sampling in primary care, according to a recent study.

“One-half of [urinary tract infections (UTIs)] are not diagnosed at the earliest opportunity in U.K. primary care,” Alastair D. Hay, FRCGP, a professor of primary care at the University of Bristol and colleagues wrote. “Our aim was to develop and internally validate a 2-step clinical rule: step 1 used symptoms and signs to select children for urine sampling, and step 2 (once urine was obtained) used symptoms, signs, and dipstick testing to guide empiric antibiotic treatment.”

Hay and colleagues enlisted acutely unwell children, aged younger than 5 years, from 233 primary care sites in Wales and England for their study. For index tests, the researchers used symptoms reported by parents, signs reported by clinicians, results from urine dipstick tests, and clinical diagnosis by clinician of UTI probability before dipstick and culture.

The researchers calculated sensitivity, specificity, and area under the receiver operator characteristic (AUROC) curve of coefficient-based (graded severity) and points-based (dichotomized) symptom/sign logistic regression models, using as the reference standard a microbiologically confirmed UTI cultured from a clean-catch urine sample. The researchers used bootstrapping to internally prove the AUROC.

Among the 3,036 children who supplied urine samples, culture results were available for 90%. Of these culture results, 2.2% were positive, meeting the U.K. microbiological criteria for UTI: Clinical diagnosis was 46.6% sensitive (AUROC = 0.77). The validated coefficient AUROC was 0.87, and the points-based model AUROC was 0.86; however, both increased to 0.9 by adding dipstick nitrites, leukocytes, and blood.

“Our results support a risk-based approach to the identification of children for investigation of UTI,” Hay and colleagues conclude. “Pain or crying while passing urine, smelly urine, previous UTI, absence of severe cough, severe illness, abdominal tenderness, and absence of ear abnormalities can be used for deciding which children for whom a urine sample (step 1) and dipstick results would improve specificity for antibiotic treatment (step 2).” – by Savannah Demko

Disclosure: The researchers report no relevant financial disclosures.