title: Interrater Reliability of the Postoperative Epidural Fibrosis Classification: A Histopathologic Study in the Rat Model.
abstract: METHODS
  Agreement study.
  
  
  OBJECTIVE
  To validate the interrater reliability of the histopathological classification of the post-laminectomy epidural fibrosis in an animal model.
  
  
  BACKGROUND
  Epidural fibrosis is a common cause of failed back surgery syndrome. Many animal experiments have been developed to investigate the prevention of epidural fibrosis. One of the common outcome measurements is the epidural fibrous adherence grading, but the classification has not yet been validated.
  
  
  METHODS
  Five identical sets of histopathological digital files of L5-L6 laminectomized adult Sprague-Dawley rats, representing various degrees of postoperative epidural fibrous adherence were randomized and evaluated by five independent assessors masked to the study processes. Epidural fibrosis was rated as grade 0 (no fibrosis), grade 1 (thin fibrous band), grade 2 (continuous fibrous adherence for less than two-thirds of the laminectomy area), or grade 3 (large fibrotic tissue for more than two-thirds of the laminectomy area). A statistical analysis was performed.
  
  
  RESULTS
  Four hundred slides were independently evaluated by each assessor. The percent agreement and intraclass correlation coefficient (ICC) between each pair of assessors varied from 73.5% to 81.3% and from 0.81 to 0.86, respectively. The overall ICC was 0.83 (95% confidence interval, 0.81-0.86).
  
  
  CONCLUSIONS
  The postoperative epidural fibrosis classification showed almost perfect agreement among the assessors. This classification can be used in research involving the histopathology of postoperative epidural fibrosis; for example, for the development of preventions of postoperative epidural fibrosis or treatment in an animal model.
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Surachai
authors.initials: S
authors.lastname: Sae-Jung
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Kitti
authors.initials: K
authors.lastname: Jirarattanaphochai
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Chat
authors.initials: C
authors.lastname: Sumananont
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Kriangkrai
authors.initials: K
authors.lastname: Wittayapairoj
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Kamolsak
authors.initials: K
authors.lastname: Sukhonthamarn
keywords: Fibrosis; Laminectomy; Pathology; Postoperative period