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SIX OF ONE, HALF A DOZEN OF THE OTHER: A MEASURE OF
MULTIDISCIPLINARY INTER/INTRA-RATER RELIABILITY OF SFU AND UTD
GRADING SYSTEMS FOR HYDRONEPHROSIS
Soojin KIM
1
, Mandy RICKARD
1
, Armando LORENZO
2
, Forough FARROKHYAR
3
, Jennifer D'CRUZ
4
, Bethany
EASTERBROOK
4
, Jorge DEMARIA
1
, Kizanee JEGATHEESWARAN
4
, Vladimir BELOSTOTSKY
5
, Steven ARORA
5
, Nina STEIN
6
,
Kelly AINSWORTH
6
, Vladimir RUZHYNSKY
7
, Natasha BROWNRIGG
1
, Carline BOZZATO
1
and Luis BRAGA
1
1) McMaster University - McMaster Children's Hospital, Department of Surgery / Urology, Hamilton, CANADA - 2) The
Hospital for Sick Children, Department of Surgery / Urology, Toronto, CANADA - 3) McMaster University, Department of
Surgery, Hamilton, CANADA - 4) McMaster University - McMaster Children's Hospital, Department of Surgery-McMaster
Pediatric Surgery Research Collaborative, Hamilton, CANADA - 5) McMaster University - McMaster Children's Hospital,
Department of Pediatrics, Hamilton, CANADA - 6) McMaster University - McMaster Children's Hospital, Department of
Radiology, Hamilton, CANADA - 7) McMaster University - McMaster Children's Hospital, Department of Urology,
Hamilton, CANADA
PURPOSE
The hydronephrosis Urinary Tract Dilation (UTD) grading system was introduced to address shortcomings of the SFU
classification. Herein we compare the intra/inter-rater reliability of both grading systems.
MATERIAL AND METHODS
SFU (I-IV) and UTD (I-III) from 50-transverse ultrasonographic views of hydronephrotic kidneys were independently
assigned by 13 raters (9 pediatric urology staff, 2 nephrologists, 2 radiologists), twice, 3 weeks apart. Ureteral diameter
and bladder images were also reviewed to allow proper UTD categorization. Ten images were repeated to assess intra-
rater reliability. Krippendorff’s Alpha was used to measure overall and by grade intra/inter-rater reliability of both
classifications. Agreement between specialties was also analyzed.
RESULTS
Overall inter-rater reliability was slightly higher for SFU (0.92/0.90) compared to UTD (0.86/0.72). Intra-rater reliability
for SFU and UTD was 0.92/0.90 and 0.86/0.72. Test/retest for SFU and UTD were 0.91 and 0.83 respectively. Table 1
shows agreement results segregated by grades and classification systems for each session. Urology agreement for SFU
classification was 0.87/0.85, similar to 0.83/0.87 for radiology and 0.87/0.78 for nephrology. UTD classification
agreement was lower for urologists at 0.76/0.74, radiologists at 0.79/0.66 and nephrologists at 0.66/0.69.
CONCLUSIONS
SFU grading system showed a higher overall intra/inter-rater reliability regardless of rater specialty compared to UTD
classification. Inter-rater reliability for SFU grades II/III and UTD II was low, highlighting the limitations of both
classifications in regards to properly segregating moderate HN grades. Urologists and radiologists showed overall higher
agreement than nephrologists, probably reflecting their greater familiarity with these grading systems.
Classification Initial Rating 95%CI
Second Rating 95%CI
SFU1
0.71
0.53-0.87 0.69
0.50-0.85
SFU2
0.40
0.19-0.60 0.34
0.12-0.55
SFU3
0.44
0.25-0.64 0.35
0.15-0.56
SFU4
0.80
0.65-0.92 0.73
0.57-0.87
UTD1
0.65
0.50-0.80 0.52
0.35-0.70
UTD2
0.46
0.28-0.64 0.27
0.05-0.47
UTD3
0.73
0.57-0.87 0.67
0.51-0.85