Inter-observer agreement for Crohn's disease sub-phenotypes using the Montreal Classification: How good are we? A...

Area of Science:

• Gastroenterology
• Clinical Epidemiology
• Inflammatory Bowel Disease Research

Background:

• Crohn's disease (CD) presents with significant clinical heterogeneity.
• Existing classification systems aim to standardize CD description.
• Reliability of classification systems hinges on inter-observer agreement (IOA).

Purpose of the Study:

• To evaluate the inter-observer agreement (IOA) of the Montreal Classification (MC) in Crohn's disease.
• To identify specific disease characteristics with varying levels of classification agreement.

Main Methods:

• De-identified clinical records of 35 CD patients were reviewed by 13 expert practitioners.
• Practitioners classified cases using the Montreal Classification (MC).
• Kappa statistics were used to assess IOA, with pre-defined agreement levels.

Main Results:

• Excellent IOA was observed for age (κ=0.84) and perianal disease at follow-up (κ=0.88).
• Good IOA was found for disease location (κ=0.73 at diagnosis, κ=0.68 at follow-up) and immunosuppressant use (κ=0.79).
• Moderate IOA was noted for upper GI disease and disease behaviour at both diagnosis and follow-up.

Conclusions:

• The Montreal Classification (MC) demonstrates generally good IOA in Crohn's disease.
• Certain aspects, like upper GI involvement and disease behaviour, show less consistent agreement.
• Inconsistencies in classification can impact the value of clinical data and hinder research translation.