Prediction of Moderate and High Grade Vesicoureteral Reflux After a First Febrile Urinary Tract Infection in Children: Construction and Internal Validation of a Clinical Decision Rule

Predictors of grade 3-5 vesicoureteral reflux in infants ≤ 2 months of age with pyelonephritis

BACKGROUND

This study aimed to assess predictors for grade 3-5 vesicoureteral reflux (VUR) in infants ≤ 2 months of age admitted for first urinary tract infection (UTI).

METHODS

Retrospective cohort study of 195 infants ≤ 2 months admitted to a pediatric ward for first UTI between 2006 and 2017. Clinical, laboratory, and imaging data were collected from electronic medical charts. We examined associations between grade 3-5 VUR and different patient characteristics.

RESULTS

Twenty infants (10%) were diagnosed with grade 3-5 VUR; all had fever. Infants with grade 3-5 VUR had higher blood neutrophil percentage (BNP) (65% vs. 46%, P < 0.001), higher neutrophil-to-lymphocyte ratio (NLR) (2.6 vs. 1.3, P < 0.001), more renal ultrasound abnormalities (prenatal 26% vs. 5%, P = 0.007; postnatal 84% vs. 55%, P = 0.015), and Pseudomonas UTI (15% vs. 1%, respectively, P < 0.001). NLR > 1.65 showed sensitivity 100% and specificity 61% for detecting grade 3-5 VUR. BNP > 53% showed sensitivity 100% and specificity 60% for detecting grade 3-5 VUR. BNP was the best single marker for grade 3-5 VUR with area under the curve (AUC) of 0.82 (95% CI 0.75-0.89). In a multivariate model, AUC for combination of BNP and hydronephrosis was 0.86 (95% CI 0.79-0.93, P = 0.007).

CONCLUSIONS

Infants ≤ 2 months of age admitted for a first UTI are at risk for grade 3-5 VUR and thus should undergo a voiding cystourethrography (VCUG) if their renal ultrasound is abnormal or if they have Pseudomonas UTI. Avoiding VCUG can be considered in afebrile infants and in infants with BNP < 53% or NLR < 1.65.

Role of procalcitonin in predicting dilating vesicoureteral reflux in young children hospitalized with a first febrile urinary tract infection

OBJECTIVE

The aim of this article was to assess the usefulness of procalcitonin (PCT) as a marker for predicting dilating (grades III-V) vesicoureteral reflux (VUR) in young children with a first febrile urinary tract infection.

METHODS

Children ≤2 years of age with a first febrile urinary tract infection were prospectively evaluated. Serum samples were tested for PCT at the time of admission to a tertiary hospital. All children underwent renal ultrasonography (US), Tc-dimercaptosuccinic acid renal scan, and voiding cystourethrography. The diagnostic characteristics of PCT test for acute pyelonephritis and dilating VUR were calculated.

RESULTS

Of 272 children analyzed (168 boys and 104 girls; median age, 5 months), 169 (62.1%) had acute pyelonephritis. There was VUR demonstrated in 97 (35.7%), including 70 (25.7%) with dilating VUR. The median PCT value was significantly higher in children with VUR than in those without (P < 0.001). Using a PCT cutoff value of ≥1.0 ng/mL, the sensitivity and negative predictive value for predicting dilating VUR were 94.3% and 95.4%, respectively, for PCT, and 97.1% and 97.8%, respectively, for the combined PCT and US studies, whereas the positive and negative likelihood ratios were 2.03 and 0.107, respectively, for PCT, and 1.72 and 0.067, respectively, for the combined studies. By multivariate analysis, high PCT values and abnormalities on US were independent predictors of dilating VUR.

CONCLUSIONS

PCT is useful for diagnosing acute pyelonephritis and predicting dilating VUR in young children with a first febrile urinary tract infection. A voiding cystourethrography is indicated only in children with high PCT values (≥1.0 ng/mL) and/or abnormalities found on a US.

[Comparative study of C-reactive protein and procalcitonin in the severity diagnosis of pyelonephritis in children]

OBJECTIVE

The aim of this study is to compare two biologic parameters; C-reactive protein (CRP) and procalcitonin (PCT) in the detection of acute renal lesions assessed by DMSA scintigraphy in the urinary tract infection in child.

DESIGN

In a prospective study, serum PCT, CRP and leukocyte counts were measured for children admitted, between January and December 2010, with a first episode of febrile urinary tract infection.

RESULTS

Seventy-five children were enrolled in the study. Thirty-three patients had renal lesions (group A) and 42 had a normal DMSA scintigraphy (group B). The mean PCT level was significantly higher in group A than in group B (8.81 ng/mL versus 1.7 ng/mL, P=0.01). In this study, using receiver operating characteristic (ROC) curve, we identified that the optimal cut-off value with ideal sensitivity and specificity for PCT in detection of renal lesions was 0.76 ng/mL and for CRP, it was 70 mg/L. The sensitivity, the negative predictive value and the indice of Youden of the cut-off value of PCT were significantly higher than CRP (82% versus 70%; 84% versus 70% and 0.58 versus 0.25).

CONCLUSIONS

This study confirmed that the serum PCT level was more sensitive and specific than the CRP in the detection of renal lesions in the first urinary tract infection in child.

[Procalcitonin, a useful biomarker in pediatric urinary tract infection]

Urinary tract infections (UTIs) are one of the most common sources of bacterial infections among young febrile children. Accurate diagnosis of acute pyelonephritis (APN) and vesico-ureteral reflux (VUR) are important because of their association with renal scarring, sometimes leading to long-term complications. However, the gold standard examinations are either a DMSA scan for APN and scarring, or cystography for VUR, but both present limitations (feasibility, pain, cost, etc.). Procalcitonin, a reliable marker of bacterial infections, was demonstrated to be a good predictor of renal parenchymal involvement in the acute phase and in late renal scars, as well as of high-grade VUR. These findings need further broad validations and impact studies before being implemented into daily practice. However, procalcitonin may play a role in the complex and still debated picture of which examination should be performed after UTI in children.

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.

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.