Polyp morphology: an interobserver evaluation for the Paris classification among international experts.

Area of Science:

• Gastroenterology
• Endoscopic diagnostics
• Medical classification systems

Background:

• The Paris classification is an international standard for polyp morphology.
• Its validity and reproducibility have not been previously assessed.
• Accurate polyp description is crucial for endoscopic diagnosis and research.

Purpose of the Study:

• To assess the interobserver agreement of the Paris classification among Western expert endoscopists.
• To determine the reliability of the Paris classification in describing polyp morphology.

Main Methods:

• Seven expert endoscopists evaluated 85 endoscopic video clips of polyps using the Paris classification.
• Interobserver agreement was measured using Fleiss kappa and pairwise agreement.
• Assessments were repeated after a digital training module.

Main Results:

• Moderate interobserver agreement was observed (Fleiss kappa = 0.42, mean pairwise agreement = 67%).
• Significant variation existed in classifying "flat" lesions (13-40%).
• Digital training did not improve interobserver agreement (kappa = 0.38).

Conclusions:

• The study is the first to validate the Paris classification for polyp morphology.
• Current interobserver agreement among experts is only moderate.
• The Paris classification, in its present form, is questionable for daily practice and comparative research, suggesting a need for simplification.