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.