Published online November 1, 2005
PEDIATRICS
Vol. 116
No. 5
November 2005, pp.
1261-1262
(doi:10.1542/peds.2005-1722)
Procalcitonin and Vesicoureteral Reflux in Children With Urinary Tract Infection
Isabelle Chevalier, MD, MSc
Marie Gauthier, MD
Department of Pediatrics
Hôpital Sainte-Justine
Université de Montréal
Montreal, Canada H3T 1C5
To the Editor.—
We read with interest the article by Leroy et al1 regarding procalcitonin as a predictor of vesicoureteral reflux (VUR) in children. The authors address an important issue: the prevention of unnecessary voiding cystourethrograms in children.
As they point out, the use of sterile bags to collect specimens for urine culture raises the possibility of selection bias in their study. We disagree with the authors, who state that selection bias does not explain their results. The specificity of bag urine specimens is poor and may lead to high false-positive rates, particularly in populations at low risk for urinary tract infection (UTI).2 In children with VUR, especially those with high-grade VUR, an increased risk of parenchymal anomalies on renal scintigraphy after a diagnosis of UTI has been described.3 For a test of a given specificity and sensitivity, the positive predictive value improves when the prevalence of the disease increases in the population tested.4 Among children with UTI diagnosed with a bag specimen, the number of children without VUR falsely diagnosed with pyelonephritis is thus likely to be higher than in a population of children with high-grade VUR. Had urine cultures been performed through transurethral bladder catheterization or suprapubic aspiration in younger children, the number of false-positive urine-culture results, particularly in children without VUR, may have been lower, thereby decreasing the magnitude of the association observed between procalcitonin and VUR. In a prior study involving 37 children with abnormal renal scintigraphy after diagnosis of UTI, including 13 children with VUR, mean procalcitonin was similar in children with and without VUR.5 The association found between procalcitonin levels and VUR by Leroy et al may simply reflect the association between procalcitonin and renal lesions after UTI5 in a population diagnosed through a technique of poor specificity.
It will be essential in future studies of the same issue to diagnose UTI with the best technique available. Transurethral bladder catheterization or suprapubic aspiration, rather than bag specimens, should be used to diagnose UTI in young children, as recommended by the American Academy of Pediatrics2 and the Canadian Paediatric Society.6 In the technical report supporting its 1999 guidelines, the American Academy of Pediatrics performed a decision analysis demonstrating that, when applied to a theoretical cohort of 100 000 children, the use of bag specimens to diagnose UTI led to 33 500 imaging work-ups. Comparatively, using transurethral catheterization reduced the number of imaging work-ups to 5000.7 These data demonstrate that, until the use of biological markers predicting the presence of VUR has been evaluated further, adopting appropriate methods for obtaining urine specimens remains an efficient strategy for reducing the needless use of voiding cystourethrograms.
REFERENCES
- Leroy S, Adamsbaum C, Marc E, et al. Procalcitonin as a predictor of vesicoureteral reflux in children with a first febrile urinary tract infection.
Pediatrics. 2005;115
(6). Available at: www.pediatrics.org/cgi/content/full/115/6/e706
- American Academy of Pediatrics, Committee on Quality Improvement, Subcommittee on Urinary Tract Infection. Practice parameter: the diagnosis, treatment, and evaluation of the initial urinary tract infection in febrile infants and young children.
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Statistical Methods in Medical Research. 3rd ed. Oxford, United Kingdom: Blackwell Science Ltd; 1994
- Benador N, Siegrist CA, Gendrel D, et al. Procalcitonin is a marker of severity of renal lesions in pyelonephritis.
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- PID note: bag urine specimens still not appropriate in diagnosing urinary tract infections in infants.
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- Downs SM. Technical report: urinary tract infections in febrile infants and young children. Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement.
Pediatrics. 1999;103
(4). Available at: www.pediatrics.org/cgi/content/full/103/4/e54
PEDIATRICS (ISSN 1098-4275). ©2005 by the American Academy of Pediatrics
Related articles in Pediatrics:
- Procalcitonin and Vesicoureteral Reflux in Children With Urinary Tract Infection: In Reply
- Sandrine Leroy, Dominique Gendrel, Gérard Bréart, and Martin Chalumeau
Pediatrics 2005 116: 1262-1263.
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