title: Polyp morphology: an interobserver evaluation for the Paris classification among international experts.
abstract: OBJECTIVE
  The Paris classification is an international classification system for describing polyp morphology. Thus far, the validity and reproducibility of this classification have not been assessed. We aimed to determine the interobserver agreement for the Paris classification among seven Western expert endoscopists.
  
  
  METHODS
  A total of 85 short endoscopic video clips depicting polyps were created and assessed by seven expert endoscopists according to the Paris classification. After a digital training module, the same 85 polyps were assessed again. We calculated the interobserver agreement with a Fleiss kappa and as the proportion of pairwise agreement.
  
  
  RESULTS
  The interobserver agreement of the Paris classification among seven experts was moderate with a Fleiss kappa of 0.42 and a mean pairwise agreement of 67%. The proportion of lesions assessed as "flat" by the experts ranged between 13 and 40% (P<0.001). After the digital training, the interobserver agreement did not change (kappa 0.38, pairwise agreement 60%).
  
  
  CONCLUSIONS
  Our study is the first to validate the Paris classification for polyp morphology. We demonstrated only a moderate interobserver agreement among international Western experts for this classification system. Our data suggest that, in its current version, the use of this classification system in daily practice is questionable and it is unsuitable for comparative endoscopic research. We therefore suggest introduction of a simplification of the classification system.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Sascha C
authors.initials: SC
authors.lastname: van Doorn
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Y
authors.initials: Y
authors.lastname: Hazewinkel
authors.affiliation: Translational Gastroenterology Unit, University of Oxford, Oxford, UK.
authors.forename: James E
authors.initials: JE
authors.lastname: East
authors.affiliation: Department of Gastroenterology and Hepatology, Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Monique E
authors.initials: ME
authors.lastname: van Leerdam
authors.affiliation: Endoscopy Department, University of Kansas School of Medicine, Kansas City, Kansas, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Rastogi
authors.affiliation: Department of Gastroenterology, Hospital Clínic, Centro de Investigación Biomédica en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), IDIBAPS, Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Pellisé
authors.affiliation: Division of Gastroenterology and Hepatology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sanduleanu-Dascalescu
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Barbara A J
authors.initials: BA
authors.lastname: Bastiaansen
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Fockens
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Evelien
authors.initials: E
authors.lastname: Dekker
mesh_terms: D003111:Colonic Polyps / Q000145:classification / Q000473:pathology*; D003113:Colonoscopy; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results