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MP64-06 SPONTANEOUS VESICOURETERAL REFLUX RESOLUTION CURVES BASED ON URETERAL DIAMETER RATIO

INTRODUCTION AND OBJECTIVES: A multitude of factors contribute to the natural course of vesicoureteral reflux (VUR), with grade often considered the gold-standard predictor. Grading is subjective with inter-observer discrepancies. Distal ureteral diameter ratio (UDR) is an objective measure reflective of ureterovesical junction anatomy that independently predicts spontaneous resolution and breakthrough UTIs in children with primary reflux. Using patients from multiple institutions, we created resolution curves based on UDR, controlling for age at diagnosis and laterality. METHODS: Voiding cystourethrograms (VCUGs) diagnosing primary VUR were reviewed. UDR was computed by measuring largest ureteral diameter within the pelvis and dividing by the distance between L1-L3 vertebral bodies. Resolution curves based on UDR were calculated using recursive partitioning methodology for time to event data, controlling for age at diagnosis and laterality. RESULTS: Three hundred and four patients (226 female, 78 male) were analyzed with a mean age at diagnosis of 1.55 ± 1.98 years and followed over time. Mean maximum VUR grade was 2.9 ± 1 and mean UDR was 0.28 ± 0.17. As expected, unilateral reflux (p = .02), VUR grades 1-3 (p<0.001), and lower UDR (p<0.001) were associated with spontaneous resolution on univariate analysis. UDR values were then categorized into risk groups, and the accuracy of spontaneous resolution prediction tested using a training (70% of patients) and test (30%) group. Low risk patients (those with UDR <0.2995) achieved VUR resolution faster and with a continuing rate compared to the high risk group (>0.2995), which had persistent reflux after 3 years (Figure A). When the 0.2995 cutoff was applied randomly to patients placed in the test group, the cutoff significantly discriminated between low and high risk patients (log rank test p = 0.02; Figure B). CONCLUSIONS: Children with primary VUR and a UDR of greater than 0.30 are unlikely to spontaneously resolve over time. UDR provides valuable prognostic information regarding projected clinical course, facilitating individualized patient management. Figure. No caption available. Source of Funding: None