Vesicoureteral Reflux Index: Predicting Primary Vesicoureteral Reflux Resolution in Children Diagnosed after Age 24 Months

Purpose: The Vesicoureteral Reflux Index is a validated tool that reliably predicts spontaneous resolution of reflux or at least 2 grades of improvement for patients diagnosed before age 24 months. We evaluated the Vesicoureteral Reflux Index in children older than 2 years. Materials and Methods: Patients younger than 18 years who were diagnosed with primary vesicoureteral reflux after age 24 months and had undergone 2 or more voiding cystourethrograms were identified. Disease severity was scored using the Vesicoureteral Reflux Index, a 6-point scale based on gender, reflux grade, ureteral abnormalities and reflux timing. Proportional subdistribution hazard models for competing risks identified variables associated with resolution/improvement at different time points. Results: A total of 21 males and 250 females met inclusion criteria. Mean +/- SD age was 4.0 +/- 2.1 years and patients had a median vesicoureteral reflux grade of 2. The Vesicoureteral Reflux Index score improved by 1 point in 1 patient (100%), 2 points in 25 (67.6%), 3 points in 48 (37%), 4 points in 18 (21.4%) and 5 to 6 points in 4 (18.2%). Female gender (p = 0.005) and vesicoureteral reflux timing (late filling, p = 0.002; early/mid filling, p < 0.001) independently predicted nonresolution. Median resolution time based on Vesicoureteral Reflux Index score was 2 months or less in 15.6% of patients (95% CI 11.0-13.8), 3 months in 34.7% (95% CI 25.4-44.1), 4 months in 55.9% (95% CI 40.1 to infinity) and 5 months or more in 30.3% (95% CI 29.5 to infinity). High grade (IV or V) reflux was not associated with resolution at any point. Ureteral abnormalities were associated with lack of resolution in the first 12 to 18 months (HR 0.29, 95% CI 0.29-0.80) but not in later followup. Vesicoureteral Reflux Index scores of 3, 4 and 5 were significantly associated with lack of resolution/improvement compared to scores of 2 or less (p = 0.031). Conclusions: The Vesicoureteral Reflux Index reliably predicts primary vesicoureteral reflux improvement/resolution in children diagnosed after age 24 months. Spontaneous resolution/improvement is less likely as Vesicoureteral Reflux Index score and time from diagnosis increase.