title: Inter-observer agreement for Crohn's disease sub-phenotypes using the Montreal Classification: How good are we? A multi-centre Australasian study.
abstract: BACKGROUND
  Crohn's disease (CD) exhibits significant clinical heterogeneity. Classification systems attempt to describe this; however, their utility and reliability depends on inter-observer agreement (IOA). We therefore sought to evaluate IOA using the Montreal Classification (MC).
  
  
  METHODS
  De-identified clinical records of 35 CD patients from 6 Australian IBD centres were presented to 13 expert practitioners from 8 Australia and New Zealand Inflammatory Bowel Disease Consortium (ANZIBDC) centres. Practitioners classified the cases using MC and forwarded data for central blinded analysis. IOA on smoking and medications was also tested. Kappa statistics, with pre-specified outcomes of κ>0.8 excellent; 0.61-0.8 good; 0.41-0.6 moderate and ≤0.4 poor, were used.
  
  
  RESULTS
  97% of study cases had colonoscopy reports, however, only 31% had undergone a complete set of diagnostic investigations (colonoscopy, histology, SB imaging). At diagnosis, IOA was excellent for age, κ=0.84; good for disease location, κ=0.73; only moderate for upper GI disease (κ=0.57) and disease behaviour, κ=0.54; and good for the presence of perianal disease, κ=0.6. At last follow-up, IOA was good for location, κ=0.68; only moderate for upper GI disease (κ=0.43) and disease behaviour, κ=0.46; but excellent for the presence/absence of perianal disease, κ=0.88. IOA for immunosuppressant use ever and presence of stricture were both good (κ=0.79 and 0.64 respectively).
  
  
  CONCLUSIONS
  IOA using MC is generally good; however some areas are less consistent than others. Omissions and inaccuracies reduce the value of clinical data when comparing cohorts across different centres, and may impair the ability to translate genetic discoveries into clinical practice.
authors.affiliation: Inflammatory Bowel Disease Research Group, Queensland Institute of Medical Research, Brisbane, Australia. krupak@qimr.edu.au
authors.forename: Krupa
authors.initials: K
authors.lastname: Krishnaprasad
authors.forename: Jane M
authors.initials: JM
authors.lastname: Andrews
authors.forename: Ian C
authors.initials: IC
authors.lastname: Lawrance
authors.forename: Timothy
authors.initials: T
authors.lastname: Florin
authors.forename: Richard B
authors.initials: RB
authors.lastname: Gearry
authors.forename: Rupert W L
authors.initials: RW
authors.lastname: Leong
authors.forename: Gillian
authors.initials: G
authors.lastname: Mahy
authors.forename: Peter
authors.initials: P
authors.lastname: Bampton
authors.forename: Ruth
authors.initials: R
authors.lastname: Prosser
authors.forename: Peta
authors.initials: P
authors.lastname: Leach
authors.forename: Laurie
authors.initials: L
authors.lastname: Chitti
authors.forename: Charles
authors.initials: C
authors.lastname: Cock
authors.forename: Rachel
authors.initials: R
authors.lastname: Grafton
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Croft
authors.forename: Sharon
authors.initials: S
authors.lastname: Cooke
authors.forename: James D
authors.initials: JD
authors.lastname: Doecke
authors.forename: Graham L
authors.initials: GL
authors.lastname: Radford-Smith
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia; D003424:Crohn Disease / Q000145:classification* / Q000175:diagnosis / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D015588:Observer Variation; D010641:Phenotype; D012720:Severity of Illness Index; D055815:Young Adult