Prediction of high-grade vesicoureteral reflux after pediatric urinary tract infection: external validation study of procalcitonin-based decision rule.
BACKGROUND
Predicting vesico-ureteral reflux (VUR) ≥3 at the time of the first urinary tract infection (UTI) would make it possible to restrict cystography to high-risk children. We previously derived the following clinical decision rule for that purpose: cystography should be performed in cases with ureteral dilation and a serum procalcitonin level ≥0.17 ng/mL, or without ureteral dilatation when the serum procalcitonin level ≥0.63 ng/mL. The rule yielded a 86% sensitivity with a 46% specificity. We aimed to test its reproducibility.


METHODS
A secondary analysis of prospective series of children with a first UTI. The rule was applied, and predictive ability was calculated.


RESULTS
The study included 413 patients (157 boys, VUR ≥3 in 11%) from eight centers in five countries. The rule offered a 46% specificity (95% CI, 41-52), not different from the one in the derivation study. However, the sensitivity significantly decreased to 64% (95%CI, 50-76), leading to a difference of 20% (95%CI, 17-36). In all, 16 (34%) patients among the 47 with VUR ≥3 were misdiagnosed by the rule. This lack of reproducibility might result primarily from a difference between derivation and validation populations regarding inflammatory parameters (CRP, PCT); the validation set samples may have been collected earlier than for the derivation one.


CONCLUSIONS
The rule built to predict VUR ≥3 had a stable specificity (ie. 46%), but a decreased sensitivity (ie. 64%) because of the time variability of PCT measurement. Some refinement may be warranted.
Centre for Statistics in Medicine, Oxford, United Kingdom. Sandrine.Leroy@pasteur.fr
Sandrine
S
Leroy
François
F
Bouissou
Anna
A
Fernandez-Lopez
Metin K
MK
Gurgoze
Kyriaki
K
Karavanaki
Tim
T
Ulinski
Silvia
S
Bressan
Geogios
G
Vaos
Pierre
P
Leblond
Yvon
Y
Coulais
Carlos Luaces
CL
Cubells
A Denizmen
AD
Aygun
Constantinos J
CJ
Stefanidis
Albert
A
Bensman
Liviana
L
Da Dalt
Liviana
L
DaDalt
Stefanos
S
Gardikis
Sandra
S
Bigot
Dominique
D
Gendrel
Gérard
G
Bréart
Martin
M
Chalumeau
D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D002648:Child; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012680:Sensitivity and Specificity; D014552:Urinary Tract Infections / Q000097:blood / Q000150:complications*; D014718:Vesico-Ureteral Reflux / Q000097:blood / Q000150:complications* / Q000175:diagnosis
C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide