PEDIATRICS Vol. 122 No. 1 July 2008, pp. 215-216 (doi:10.1542/peds.2008-0465)
LETTER TO THE EDITOR |
Therapeutic Delay in Infant Urinary Tract Infection: Does It Really Have No Impact?
Pavel Geier, MD, PhDDepartment of Pediatrics
Jan Strojil, MD
Department of Pharmacology
Kate
ina Kutrová, MD
Department of Pediatrics
Faculty of Medicine and Dentistry
Palacky University
775 15 Olomouc, Czech Republic
To the Editor.—
We read with interest the article entitled "Does Early Treatment of Urinary Tract Infection Prevent Renal Damage?" by Doganis et al in the October 2007 issue of Pediatrics Electronic Pages.1 The authors presented a very interesting and methodically well-thought-out study that aimed to answer an important clinical question that could significantly influence clinical practice.
The inclusion criteria and methodology of the study were commendable; the authors went to great length to ensure the quality of the data. The first part of the article was well planned and well described, which makes it all the more surprising when the authors failed to comment on the fact that the second renal scan was only performed on 86 of the 158 infants who had had a positive renal scan result in the acute phase. This represents a 46% loss to follow-up, which could have a great impact on the significance of the final results. Ten more subjects were excluded from the analysis for reasons that are well explained (urinary tract infection relapse).
The study failed to detect a significant difference in the incidence of renal scarring between early and late onset of treatment in those who had acute changes. The authors went on to conclude that therapeutic delay is not associated with permanent damage. We feel this conclusion is unjustified given the loss of subjects to follow-up. Unfortunately, the authors failed to account for these missing subjects.
We believe that the loss of subjects could have introduced significant bias into the results. For example, more subjects who completed the study had vesicoureteric reflux (VUR) (37% vs 24.5% at the start of the study). Infants with VUR had a higher incidence of scarring (64% vs 44%). It could be argued that infants without VUR were less likely to complete follow-up, because they did not require medical attention and the parents felt that another scan was unnecessary.
Also, there were more infants older than 6 months in the group that completed follow-up (32% vs 25%), and again, this is the group that had a higher incidence of kidney damage, both acute and late (74% vs 51% and 58% vs 48%, respectively). This, also, could have introduced bias.
Most important is that the authors in their conclusions ignored the significantly lower number of cases of acute renal involvement in the early treatment group. This should have been included in the analysis, because it can be assumed that those with no acute involvement also had no late complications.2 If we include this effect in the analysis, we reach a significant protective effect of early treatment on the incidence of late scarring (P = .01). The inclusion of only those with an abnormal initial scan result would imply that the authors considered only patients with abnormal scan results to have acute pyelonephritis; however, they did not discuss this in their article. We feel that including all the subjects in the analysis would more closely reflect the real-life efficacy of early treatment.
This study, which dealt with an important pediatric issue, is very interesting and much needed, but we are afraid that such a strong conclusion might lead to a misunderstanding that early treatment of acute febrile urinary tract infections has no impact on outcome. The results did not demonstrate an effect of early treatment on scar formation, but it cannot be definitely ruled out because of potentially significant methodologic problems.
REFERENCES
1. Doganis D, Siafas K, Mavrikou M, et al. Does early treatment of urinary tract infection prevent renal damage? Pediatrics.2007; 120 (4). Available at: www.pediatrics.org/cgi/content/full/120/4/e922
2. Hoberman A, Charron M, Hickey RW, Baskin M, Kearney DH, Wald ER. Imaging studies after a first febrile urinary tract infection in young children.
N Engl J Med.2003; 348
(3):195
–202
PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics
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