Predicting Breakthrough Urinary Tract Infection: Comparative Analysis of Vesicoureteral Reflux Index, Reflux Grade and Ureteral Diameter Ratio.

Purpose: The vesicoureteral reflux index is a simple, validated tool for predicting resolution of reflux. Along with likelihood of spontaneous resolution identification of children at risk for febrile urinary tract infection impacts management. We evaluated the usefulness of the vesicoureteral reflux index as a predictive factor for breakthrough febrile urinary tract infection compared to reflux grade and distal ureteral diameter ratio.
Materials and Methods: Children with primary vesicoureteral reflux and detailed voiding cystourethrogram data were identified. A 1 to 6-point index was assigned, and ureteral diameter ratio was computed by measuring largest ureteral diameter within the pelvis and dividing by the distance between L1 to L3 vertebral bodies. Random forest modeling and logistic multivariable regression were employed to estimate the predictive ability of grade, ureteral diameter ratio and vesicoureteral reflux index with regard to breakthrough febrile urinary tract infection.
Results: We analyzed 94 girls and 45 boys with a mean±SD age of 5.4±4.7 months at diagnosis. Mean±SD length of followup was 32.1±24.5 months. A total of 13 children (9.4%) experienced breakthrough febrile urinary tract infection. On univariate analysis ureteral diameter ratio (p=0.01) and vesicoureteral reflux index (p=0.0005) were associated with breakthrough urinary tract infection, while grade (p=0.09) did not reach significance. Area under the curve was generated as a measure of accuracy for each variable and was 0.77 for the vesicoureteral reflux index, 0.71 for ureteral diameter ratio and 0.68 for grade, indicating superiority of the vesicoureteral reflux index for predicting breakthrough febrile urinary tract infection.
Conclusions: Children with higher vesicoureteral reflux index are at increased risk for breakthrough febrile urinary tract infection independent of reflux grade. The vesicoureteral reflux index provides valuable prognostic information about infection risk, facilitating improved clinical decision making.