Interobserver agreement on histopathological lesions in class III or IV lupus nephritis.
OBJECTIVE
To treat lupus nephritis effectively, proper identification of the histologic class is essential. Although the classification system for lupus nephritis is nearly 40 years old, remarkably few studies have investigated interobserver agreement. Interobserver agreement among nephropathologists was studied, particularly with respect to the recognition of class III/IV lupus nephritis lesions, and possible causes of disagreement were determined.


METHODS
A link to a survey containing pictures of 30 glomeruli was provided to all 360 members of the Renal Pathology Society; 34 responses were received from 12 countries (a response rate of 9.4%). The nephropathologist was asked whether glomerular lesions were present that would categorize the biopsy as class III/IV. If so, additional parameters were scored. To determine the interobserver agreement among the participants, κ or intraclass correlation values were calculated. The intraclass correlation or κ-value was also calculated for two separate levels of experience (specifically, nephropathologists who were new to the field or moderately experienced [less experienced] and nephropathologists who were highly experienced).


RESULTS
Intraclass correlation for the presence of a class III/IV lesion was 0.39 (poor). The κ/intraclass correlation values for the additional parameters were as follows: active, chronic, or both: 0.36; segmental versus global: 0.39; endocapillary proliferation: 0.46; influx of inflammatory cells: 0.32; swelling of endothelial cells: 0.46; extracapillary proliferation: 0.57; type of crescent: 0.46; and wire loops: 0.35. The highly experienced nephropathologists had significantly less interobserver variability compared with the less experienced nephropathologists (P=0.004).


CONCLUSIONS
There is generally poor agreement in terms of recognizing class III/IV lesions. Because experience clearly increases interobserver agreement, this agreement may be improved by training nephropathologists. These results also underscore the importance of a central review by experienced nephropathologists in clinical trials.
Departments of Pathology and s.wilhelmus@lumc.nl.
Suzanne
S
Wilhelmus
Department of Medicine, Imperial College, London, United Kingdom;
H Terence
HT
Cook
Department of Pathology, Necker Hospital, French National Institute of Health and Medical Research (INSERM) U845, Paris, France; and.
Laure-Hélène
LH
Noël
Nephropathology Center, San Gerardo Hospital, Monza, Italy.
Franco
F
Ferrario
Medical Statistics, Leiden University Medical Center, Leiden, The Netherlands;
Ron
R
Wolterbeek
Departments of Pathology and.
Jan A
JA
Bruijn
Departments of Pathology and.
Ingeborg M
IM
Bajema
D001706:Biopsy; D006801:Humans; D007678:Kidney Glomerulus / Q000473:pathology*; D008181:Lupus Nephritis / Q000145:classification / Q000473:pathology*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index
SLE; lupus nephritis; pathology