Vesicoureteral reflux index (VURx): a novel tool to predict primary reflux improvement and resolution in children less than 2 years of age.

Purpose: Surgical correction of vesicoureteral reflux (VUR) is influenced by recurrent urinary tract infection (UTI) risk and the likelihood of spontaneous resolution. We aimed to identify factors associated with VUR resolution in children less than 2 years of age and to design a simple scoring tool to predict improvement and resolution.

Materials And Methods: Children less than 2 years old with primary VUR were identified. Patient demographics, voiding cystourethrogram (VCUG) findings and clinical outcomes over time were assessed. Multivariate analysis with time to resolution was performed to identify factors predictive of VUR improvement and resolution. A random forest model was used to confirm the VUR index (VURx) with normalized importance.

Results: Two-hundred and twenty-nine children met all inclusion criteria. Mean age at initial VCUG was 0.46±0.43 years. Median clinical follow-up was 1.6 years (range 0.5-4.4 years). Children with grade 4-5 reflux, complete ureteral duplication or periureteral diverticula, and filling phase VUR, as well as female gender, had significantly (p<0.01) longer time to improvement or resolution on multivariate survival analysis. VURx 1 to 5-6 had improvement/resolution rates of 89%, 69%, 53%, 16% and 11%, respectively.

Conclusions: Female gender, high-grade VUR, ureteral anomalies, and filling reflux are associated with longer time to improvement and non-resolution. VURx reliably predicts resolution of primary reflux in children less than 2 years of age.