Ureteral diameter ratio cut-off for risk stratification of recurrent urinary tract infection and clinical outcomes in children with primary vesicoureteral reflux: a retrospective cohort study

Abstract

Ureteral diameter ratio (UDR) has recently emerged as an objective imaging parameter that may complement the conventional vesicoureteral reflux (VUR) grading system. This study investigated the association between UDR, recurrent urinary tract infections (UTIs), and clinical outcomes in children with primary VUR and explored an optimal UDR threshold for identifying patients at increased clinical risk. This retrospective cohort study included 176 children with primary VUR diagnosed at a tertiary pediatric referral center between 2016 and 2022. UDR was measured on voiding cystourethrogram (VCUG) images using the maximal visible distal ureteral diameter relative to the L1–L3 vertebral distance. Patients were followed for 12 months after diagnosis. Clinical outcomes included spontaneous resolution, persistent stable disease, recurrent UTIs, and surgical management. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory performance of UDR for recurrent UTIs. The study included 176 children (55.1% female) with a mean age of 38.3 ± 41.0 months. During follow-up, spontaneous resolution occurred in 60 patients (34.1%), 46 (26.1%) remained clinically stable, 70 (39.8%) underwent surgical management, and 39 (22.2%) experienced recurrent UTIs. Mean UDR increased progressively with VUR severity and differed significantly across clinical outcome groups ( p < 0.001). Children with recurrent UTIs had significantly higher UDR values than those without recurrent infections (0.67 ± 0.27 vs. 0.29 ± 0.21, p < 0.001). ROC analysis demonstrated good discriminatory performance of UDR for recurrent UTIs (AUC = 0.88). A UDR threshold of ≥ 0.328 yielded a sensitivity of 94.9% and a specificity of 67.9%. Higher UDR values were significantly associated with recurrent UTIs, increasing VUR severity, and less favorable clinical outcomes in children with primary VUR. A UDR threshold of ≥ 0.328 showed good diagnostic performance for identifying patients at increased risk of recurrent infection in this cohort. Because this threshold was derived from a single retrospective cohort and multivariable analysis was not available, external validation in independent populations is required before routine clinical implementation.