VUR timing on VCUG as a predictive factor of VUR resolution after endoscopic therapy.

Background: The timing of reflux onset on VCUG (VUR timing) has been considered a predictive factor of spontaneous resolution in VUR children. While the voiding reflux is associated with a greater rate of spontaneous resolution, the filling reflux is more likely to require surgical intervention. However, the VUR timing in children with primary VUR has not been evaluated with regard to the prognostic value of endoscopic therapy. The aim of this study was to evaluate the effect of VUR timing on the surgical outcome after endoscopic therapy for primary VUR.

Method: We retrospectively reviewed the medical records of 94 primary VUR patients who underwent endoscopic injection for their initial surgical management. Radiologic success was defined as grade I or less on VCUG at 3-6 months following endoscopic therapy. We allocated patients to a filling reflux group or a voiding reflux group on the basis of their most recent preoperative VCUG. We evaluated the patients' demographics and outcomes after endoscopic therapy according to VUR timing. Predictive factors for radiologic success were analyzed using a multivariate logistic regression model.

Results: Of the 94 children (136 ureters), 68 (101 ureters) were classified as the filling reflux group and 26 (35 ureters) were placed in the voiding reflux group. The preoperative VUR grade in the filling reflux group was significantly higher than that in the voiding reflux group (p = 0.001). Radiologic success was observed in 56.44% (57/101 ureters) in the filling reflux group and in 88.57% (31/35 ureters) in the voiding reflux group (p = 0.001). Multivariate analysis showed that VUR grade and VUR timing on VCUG were predictive factors of radiologic success after endoscopic therapy (p = 0.001 and p = 0.005).

Conclusions: Despite the clinical importance of VUR timing, no studies have investigated the prognostic value of VUR timing for endoscopic therapy in primary VUR children. In this study, multivariate analysis revealed that the VUR grade and VUR timing on preoperative VCUG were significant predictors of success after endoscopic injection. Although the VUR grade is the most well-known factor that can affect the success of the procedure, VUR timing was a newly identified predictive factor. While patients with a filling reflux have lower success rates, patients with a voiding reflux were observed to show higher resolution rates after endoscopic injection. VUR timing on preoperative VCUG was found to be an independent predictive factor of VUR resolution after endoscopic therapy.