title: Interobserver agreement for Polyomavirus nephropathy grading in renal allografts using the working proposal from the 10th Banff Conference on Allograft Pathology.
abstract: A classification schema for grading Polyomavirus nephropathy was proposed at the 2009 Banff allograft meeting. The schema included 3 stages of Polyomavirus nephropathy: early (stage A), florid (stage B), and late sclerosing (stage C). Grading categories for histologic viral load levels were also proposed. To examine the applicability and the interobserver agreement of the proposed Polyomavirus nephropathy grading schema, we evaluated 24 renal allograft biopsies with confirmed Polyomavirus nephropathy by histology and SV40. Four renal pathologists independently scored the Polyomavirus nephropathy stage (A, B, or C), without knowledge of the clinical history. Viral load was scored as a percent of tubules exhibiting viral replication, using either a 3-tier viral load score (1: ≤1%; 2: >1%-10%; 3: >10%) or a 4-tier score (1: ≤1%; 2: >1%-≤5%; 3: >5%-15%; 4: >15%). The κ score for the Polyomavirus nephropathy stage was 0.47 (95% confidence interval, 0.35-0.60; P < .001). There was a substantial agreement using both the 3-tier and the 4-tier scoring for the viral load (Kendall concordance coefficients, 0.72 and 0.76, respectively; P < .001 for both). A better complete agreement was found using the 3-tier viral load score. In this first attempt to evaluate the interobserver reproducibility of the proposed Polyomavirus nephropathy classifying schema, we demonstrated moderate κ agreement in assessing the Polyomavirus nephropathy stage and a substantial agreement in scoring the viral load level. The proposed grading schema can be applied in routine allograft biopsy practice for grading the Polyomavirus nephropathy stage and the viral load level.
authors: Department of Pathology and Laboratory Medicine, Calgary Laboratory Services and University of Calgary, Calgary, T2V 1P9 Alberta, Canada.
authors: Aylin
authors: A
authors: Sar
authors: Suchin
authors: S
authors: Worawichawong
authors: Hallgrimur
authors: H
authors: Benediktsson
authors: Jianguo
authors: J
authors: Zhang
authors: Serdar
authors: S
authors: Yilmaz
authors: Kiril
authors: K
authors: Trpkov
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001706:Biopsy; D002648:Child; D005260:Female; D006084:Graft Rejection / Q000145:classification / Q000188:drug therapy / Q000473:pathology* / Q000821:virology; D006801:Humans; D007668:Kidney / Q000473:pathology / Q000821:virology; D007674:Kidney Diseases / Q000145:classification / Q000188:drug therapy / Q000473:pathology* / Q000821:virology; D016030:Kidney Transplantation / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011120:Polyomavirus / Q000502:physiology*; D027601:Polyomavirus Infections / Q000145:classification / Q000188:drug therapy / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014184:Transplantation, Homologous / Q000473:pathology; D014412:Tumor Virus Infections / Q000145:classification / Q000188:drug therapy / Q000473:pathology*; D019562:Viral Load; D014779:Virus Replication