by Sandrine Leroy, François Bouissou, Anna Fernandez-Lopez, Metin K. Gurgoze, Kyriaki Karavanaki, Tim Ulinski, Silvia Bressan, Geogios Vaos, Pierre Leblond, Yvon Coulais, Carlos Luaces Cubells, A. Denizmen Aygun, Constantinos J. Stefanidis, Albert Bensman, Liviana DaDalt, Stefanos Gardikis, Sandra Bigot, Dominique Gendrel, Gérard Bréart, Martin Chalumeau
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. Study Design
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.