Reliability of voiding cystourethrogram for the grading of vesicoureteral reflux

The voiding cystourethrogram (VCUG) is a commonly employed radiographic test used in the management of vesicoureteral reflux (VUR). Recently, the reliability of VCUG to accurately grade VUR has been questioned. The purpose of this study is to examine reliability of the VCUG for the grading of VUR in a setting mimicking daily practice in a busy pediatric hospital.

Two-hundred consecutive VCUGs were independently graded by two pediatric urologists and two pediatric radiologists according to the International Classification of Vesicoureteral Reflux. A weighted kappa coefficient was calculated to determine inter-rater agreement and a modified McNemar test was performed to assess rater bias. Further assessment for impact on clinical and research decision-making was made for disagreement between grades II and III.

Weighted kappa values reflect strong reliability of VCUG for grading VUR between and among urologists and radiologists ranging from 0.95 to 0.97. There was statistically significant bias with radiologists reporting higher grades. Despite high kappa values, disagreement between raters was not infrequent and most common for grades II-IV.

VCUG is reliable for grading VUR, but small differences in grading between raters were detected and may play an important role in clinical decision-making and research outcomes.