Original article Variation in the diagnosis of vesicoureteric reflux using micturating cystourethrography Jonathan C. Craig 1 *, Les M. Irwig 3 , James Christie 2 , Albert Lam 2 , Ella Onikul 2 , John F. Knight 1 , Premala Sureshkumar 1 , and L. Paul Roy 1 1 Centre for Kidney Research, New Children’s Hospital, Sydney, Australia 2 Department of Radiology, New Children’s Hospital, Sydney, Australia 3 Department of Public Health, University of Sydney, Sydney, Australia Received June 19, 1996; received in revised form November 1, 1996; accepted December 6, 1996 Abstract. Variability in the interpretation of micturating cystourethrography by paediatric radiologists for the diag- nosis of vesicoureteric reflux in children was evaluated. All 265 micturating cystourethrograms (MCUs) that were available from 304 consecutive children aged 0.5 – 61 months – who were investigated after their first urine in- fection between 1993 and 1995 as part of a prospective cohort study – were selected for interpretation. Three ex- perienced paediatric radiologists from the same department independently interpreted the MCUs according to the grading system of the International Reflux Study in Chil- dren, from grades 0 to V, with the presence of intrarenal reflux also noted. Apart from being informed that urine infection was the indication for the MCU, no other clinical information was given to the radiologists. The indices of variability used were the percentage of agreement and the kappa statistic, expressed as a percentage. Both measures were weighted with integers representing the number of categories from perfect agreement. Disagreement was analysed for children and kidneys. For the diagnosis of vesicoureteric reflux in individual patients, including grade, the percentage of agreement was 96% – 97% (kappa 90% – 91%) and the weighted percentage of agreement was 96% – 98% (weighted kappa 93% – 94%). The same high level of agreement was present for individual kidneys, with a percentage of agreement of 97% – 98% (kappa 89% – 92%) and a weighted percentage of agreement of 98% – 99% (kappa 94% – 95%). There was near perfect agreement in the interpretation of radiological micturating cystourethrography among three experienced paediatric radiologists for the diagnosis and grade of vesicoureteric reflux. Any variations in the medical care of children sus- pected of having vesicoureteric reflux are not explained by differences in the reporting of this diagnostic test. Key words: Vesicoureteric reflux – Micturating cystoure- throgram – Observer variation – Urinary tract infection Introduction Despite a considerable body of literature concerning the technical aspects of radiological contrast micturating cy- stourethrography in children [1, 2], and the management implications for those children found to have vesicoureteric reflux [3 – 6], the extent of radiologists’ variability in in- terpretation of this commonly used test has not been ex- amined. In a search of the medical literature using the MEDLINE database (January 1966 to May 1996) and with the following search strategies, we were unable to find any relevant study. Medical subject headings were “vesicour- eteral reflux” and “observer variability”, and the text terms were “variability”, “kappa”, “agreement”, “micturating cystourethrography”, “voiding cystourethrography”, “MCU”, “MCUG”, “MCU”, “VCUG”. Additional litera- ture, not identified by the computerised search, was sought by review of article reference lists. We conducted a study to determine the extent of variability in the interpretation of micturating cystourethrography by radiologists for the di- agnosis of vesicoureteric reflux. Patients and methods Patient selection. Patients were drawn from a prospective hospital- based cohort study of children under 5 years of age with their first documented urine infection who presented between March 1993 and December 1994. Of the 304 eligible children, micturating cystoure- thrograms (MCUs) from 265 (87%) were able to be reviewed for this study. Institutional ethics approval had been given for the cohort study, and informed consent was obtained from the parents of children who participated. Participating radiologists. Three of the four radiologists who are on the staff of the New Children’s Hospital and who routinely report MCUs were invited to participate. All three are fully qualified paedi- atric radiologists, with 9 – 21 years of experience reading MCUs. Each radiologist had read 600–700 MCUs in the year before the study, and 5% of their time was spent reading MCUs in routine clinical practice. Data acquisition. All three radiologists independently read the MCUs for all patients, which were displayed on radiographic film. For the * Present address: Department of Nephrology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8 Correspondence to: J. C. Craig Pediatr Nephrol (1997) 11: 455 – 459  IPNA 1997