Performance of the Montreal classification for inflammatory bowel diseases

AIM:To validate the Montreal classification system for Crohn’s disease(CD) and ulcerative colitis(UC) within the Netherlands.METHODS:A selection of 20 de-identified medical records with an appropriate representation of the inflammatory bowel disease(IBD) sub phenotypes were scored by 30 observers with different professions(gastroenterologist specialist in IBD,gastroenterologist in training and IBD-nurses) and experience level with IBD patient care.Patients were classified according to the Montreal classification.In addition,participants were asked to score extra-intestinal manifestations(EIM) and disease severity in CD based on their clinical judgment.The inter-observer agreement was calculated by percentages of correct answers(answers identical to the 'expert evaluation') and Fleiss-kappa(k).Kappa cutoffs: 0.8 excellent.RESULTS:The inter-observer agreement was excellent for diagnosis(k = 0.96),perianal disease(k = 0.92) and disease location in CD(k = 0.82) and good for age of onset(k = 0.67),upper gastrointestinal disease(k = 0.62),disease behaviour in CD(k = 0.79) and disease extent in UC(k = 0.65).Disease severity in UC was scored poor(k = 0.23).The additional items resulted in a good inter-observer agreement for EIM(k = 0.68) and a moderate agreement for disease severity in CD(k = 0.44).Percentages of correct answers over all Montreal items give a good reflection of the inter-observer agreement(> 80%),except for disease severity(48%-74%).IBD-nurses were significantly worse in scoring upper gastrointestinal disease in CD compared to gastroenterologists(P = 0.008) and gastroenterologists in training(P = 0.040).Observers with less than 10 years of experience were significantly better at scoring UC severity than observers with 10-20 years(P = 0.003) and more than 20 years(P = 0.003) of experience with IBD patient care.Observers with 10-20 years of experience with IBD patient care were significantly better at scoring upper gastrointestinal disease in CD tha