title: Inter-rater reliability of distal ureteral diameter ratio compared to grade of VUR.
abstract: OBJECTIVE
  Management of vesicoureteral reflux (VUR) remains controversial, and reflux grade constitutes an important prognostic factor. Recent work has suggested that distal ureteral diameter ratio (UDR) is a predictive factor relative to clinical outcome independent of grade. Previous studies have noted significant inter-rater variability with grading of VUR. The present study compared inter-rater reliability of reflux grade and UDR in children with primary VUR.
  
  
  METHODS
  Four pediatric urologists independently reviewed, in a blinded fashion, voiding cystourethrograms. For each renal unit, grade was assigned according to the standardized international scale. The UDR was calculated by dividing the largest ureteral diameter within the false pelvis by the distance between L1-L3 vertebral bodies. Correlation within each rater was determined using Pearson's correlation coefficient. Reliability of VUR grade and UDR were calculated using two-way ANOVA model inter-rater agreement.
  
  
  RESULTS
  Four independent raters reliably measured VUR grade (ICC = 0.87, 95% CI = 0.78-0.93) and UDR (ICC = 0.95, 95% CI = 0.92-0.97). While UDR and grade were equally reliable measures, UDR had a tighter confidence interval. For each rater, grade and UDR were well correlated (r = 0.73-0.84; P < 0.0001). For higher-grade reflux, grade was more variable than UDR (Summary Figure). Using empirical thresholds, the increased variability of grade compared with UDR may lead to significant differences in clinical decision-making among physicians (P = 0.022).
  
  
  CONCLUSIONS
  Known discordance with grading reflux emphasizes the need for a more objective VUR measurement, as clinicians and parents often opt for clinical intervention based on both clinical course and the likelihood of spontaneous resolution. While ICC for UDR and grade were not significantly different, the confidence intervals for grade were wider due to greater variability among grade measurements. This suggests that using UDR measurements may lead to more accurate characterization of VUR and ultimately more consistent clinical decision-making across providers.
  
  
  CONCLUSIONS
  Ureteral diameter ratio has good inter-rater reliability among pediatric urologists, with less clinically relevant variability than VUR grade. Ureteral diameter ratio is a more objective and reliable measure than grade, and may be more useful in clinical decision-making.
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Swanton
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA; Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Arlen
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Alexander
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA; Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kieran
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA; Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Storm
authors.affiliation: Department of Urology, University of Iowa Hospitals and Clinics, Iowa City, IA, USA. Electronic address: christopher-cooper@uiowa.edu.
authors.forename: C S
authors.initials: CS
authors.lastname: Cooper
mesh_terms: D002648:Child; D002675:Child, Preschool; D000070621:Cystography / Q000379:methods*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D014513:Ureter / Q000000981:diagnostic imaging* / Q000503:physiopathology; D018666:Ureteroscopy / Q000379:methods; D014718:Vesico-Ureteral Reflux / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery
keywords: Grade; Ureteral diameter ratio (UDR); Vesicoureteral reflux (VUR)