of diagnostic test accuracy studies in ambulatory care (Ann Fam Med 2021;19:437-46).
“Urine sampling is often restricted to children with clinical features such as pain while urinating, frequent urination or children presenting with fever without any abnormalities found on clinical examination,” said lead author Jan Y. Verbakel, MD, PhD, from the University of Leuven (Belgium) in an interview. “Our study findings suggest that, in children, pain while urinating or frequent urination are less accurate than in adults and increase the probability of UTI only moderately.”
Urine sampling “should be applied more broadly in ambulatory care, given that appropriate sampling techniques are available,” he and his coauthors advised in the paper.
Methods and results
The analysis included 35 studies, involving a total of 78,427 patients, which provided information on 58 clinical features and 6 prediction rules of UTI, compared with urine culture. For urine sampling, most studies used catheterization (n = 23), suprapubic aspiration (n = 17), or midstream catch (n = 14), and fewer studies used clean catch (n = 7), bag specimens (n = 5), or diaper pads (n = 2).
The study showed that only three features substantially decreased the likelihood of UTI: being circumcised, the presence of stridor, and the presence of diaper rash. “In febrile children, finding an apparent source of infection decreased the probability of UTI; however, this was not useful for ruling out UTI by itself,” the authors noted.
Additionally, they found that red flags for UTI were cloudy or malodorous urine, hematuria, no fluid intake, suprapubic tenderness, and loin tenderness.
“We recommend to sample urine in children that have one or more features that increase the probability of UTI … and less so pain while urinating, frequent urination, urgency, bed wetting, or previous UTI history,” said Dr. Verbakel, who is also a researcher at the University of Oxford (England).
In terms of prediction rules, the analysis showed the Diagnosis of Urinary Tract Infection in Young Children (DUTY) score, Gorelick Scale score, and UTIcalc might be useful to identify which children should have urine sampling, the authors stated in the paper.
Specifically, a DUTY clean-catch score of less than one point was useful for ruling out UTI in children aged less than 5 years, and in girls aged less than 3 years with unexplained fever. The Gorelick Scale score was useful for ruling out UTI when less than two of five variables were present.
“The present meta-analyses confirm that few clinical features are useful for diagnosing or ruling out UTI without further urine analysis. Signs and symptoms combined in a clinical prediction rule, such as with the DUTY or UTIcalc score, might increase accuracy for ruling out UTI; however, these should be validated externally,” Dr. Verbakel said in an interview.
Is urine sampling guideline too broad?
Commenting on the new paper, Martin Koyle, MD, former division chief of urology at the Hospital for Sick Children and professor of surgery at the University of Toronto, expressed concern that unexplained fever is not included as a “differentiating” red flag.