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Polyp Morphology: An Interobserver Evaluation for the Paris Classification Among International Experts

van Doorn, Sascha C MD1; Hazewinkel, Y MD1; East, James E MD2; van Leerdam, Monique E MD, PhD3; Rastogi, Amit MD4; Pellisé, Maria MD, PhD5; Sanduleanu-Dascalescu, Silvia MD, PhD6; Bastiaansen, Barbara A J MD1; Fockens, Paul MD, PhD1; Dekker, Evelien MD, PhD1

American Journal of Gastroenterology: January 2015 - Volume 110 - Issue 1 - p 180–187
doi: 10.1038/ajg.2014.326

OBJECTIVES: 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.

1Department of Gastroenterology and Hepatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands

2Translational Gastroenterology Unit, University of Oxford, Oxford, UK

3Department of Gastroenterology and Hepatology, Netherlands Cancer Institute, Amsterdam, The Netherlands

4Endoscopy Department, University of Kansas School of Medicine, Kansas City, Kansas, USA

5Department of Gastroenterology, Hospital Clínic, Centro de Investigación Biomédica en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), IDIBAPS, Barcelona, Spain

6Division of Gastroenterology and Hepatology, Maastricht University Medical Center, Maastricht, The Netherlands

Correspondence: Evelien Dekker, Evelien Dekker, MD, PhD, Department of Gastroenterology and Hepatology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, AZ 1105, The Netherlands. E-mail:

Guarantor of the article: Sascha C. van Doorn, MD.

Specific author contributions: S.C. van Doorn: study concept and design, acquisition of data, analysis and interpretation of data, drafting of the manuscript, and statistical analysis; Y. Hazewinkel: study concept and design and critical revision of the manuscript for important intellectual content; J.E. East, M.E. van Leerdam, A. Rastogi, M. Pellise, S.Sanduleanu, E.Dekker: acquisition of data and critical revision of the manuscript for important intellectual content; B.A.J.Bastiaansen: acquisition of data.P.Fockens: critical revision of the manuscript for important intellectual content.

Financial support: None.

Potential competing interests: None.

SUPPLEMENTARY MATERIAL accompanies this paper at,

© The American College of Gastroenterology 2015. All Rights Reserved.
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