Impact of Consensus Definitions on Identification of Glomerular Lesions by Light and Electron Microscopy

Abstract

Introduction: In 2020, a working group of 13 renal pathologists published consensus definitions for 47 individual glomerular lesions found on light microscopy (LM) and 47 glomerular lesions and 9 normal structures found on electron microscopy (EM).

Methods: To test the impact of these definitions on identification of these lesions and structures, 2 surveys were circulated to all members of the Renal Pathology Society (RPS), each having 32 images (19 LM, 13 EM) and accompanying questions with 5 multiple-choice answers, one being the consensus choice of the working group. The first survey (survey 1 [S1]), answered by 297 RPS members, was sent in September 2020, before publication of the consensus definitions. The second (survey 2 [S2]), with images of the same lesions and structures (but not the same images) and the same questions and multiple choices in different order, was sent in April 2020, 5 months after the publication of the definitions.

Results: S2 was taken by 181 RPS members; 64% also took S1 and 61% reported having read the definitions paper (def. paper). Mean agreement with the consensus answers increased modestly between the 2 surveys (65.2% vs. 72.0%, P = 0.097); the increase was greater and significant when only respondents to S2 who read the def. paper were considered (65.2% vs. 74.8%, P = 0.026). Furthermore, in S2 agreement with consensus answers was greater among respondents who read this paper versus those who did not (66.9% vs. 74.8%, P < 0.0001).

Conclusions: Publication of the consensus definitions modestly improved interobserver agreement in identification of glomerular lesions.

Keywords: electron microscopy; glomerulonephritis; glomerulus; kidney biopsy; renal pathology.

Graphical abstract

Figure 1

Comparison of findings of S1 versus S2. The horizontal axis lists the 32 lesions and structures depicted in the surveys in descending order based on the percent agreement with the consensus diagnosis in S1. The lines represent the percent of all respondents (n = 297 for S1, n = 181 for S2, and n = 111 for S2 respondents who read the def. paper) agreeing with the consensus answer for each of the 32 images, with the means of the 32 values represented by the points at the far right. P values, determined by paired t tests, were 0.097 for S1 versus S2 and 0.026 for S1 versus S2 respondents who read the def. paper. def. paper, definitions paper; S1, survey 1; S2, survey 2.

Figure 2

Comparison of findings within S2 in respondents who did (n = 114) or did not (n = 67) read the def. paper. The order in which the 32 images depicted in the survey are plotted is the same as used in Figure 1. (a) For all respondents to S2, comparison of the fractions agreeing with the consensus answer for each of the 32 images. (b) For respondents to S2 who completed S1, comparison of the fractions agreeing with the consensus answer for all 32 questions among those who did (n = 77) and did not (n = 39) read the def. paper. (c) For respondents to S2 who did not complete S1, comparison of the fractions agreeing with the consensus answer for all 32 questions among those who did (n = 34) and did not (n = 31) read the def. paper. For each figure, the means of the 32 values for each survey represented by the points at the far right and the P value found were determined by t test for paired samples (n = 32). def. paper, definitions paper; S1, survey 1; S2, survey 2.

Figure 3

Images from questions for which agreement of respondents to both surveys with the consensus answers was ≤50%: (a, b) membranoproliferative pattern and (c, d) an intracapillary thrombus with glomerular basement membrane duplication. Images a and c are from survey 1 and b and d are from survey 2. Note that the images in a and b also reveal a nodular-like pattern of mesangial expansion and that those in c and d reveal visceral epithelial cell hypertrophy without true hyperplasia. Original magnification of all images ×400; a: periodic acid–Schiff stain, b–d: Jones methenamine silver stain; bars in each image = 70 μm.