Magnetic resonance imaging (MRI) is the gold standard for assessment of perianal fistulising Crohn's disease.
The Van Assche index is the most commonly used MRI fistula index.
Dr Jairath and colleagues from Canada assessed the reliability of the Van Assche index, and modified the instrument to improve reliability and create a novel index for fistulizing Crohn's disease.
A consensus process developed scoring conventions for existing Van Assche index component items and new items.
There were 4 experienced radiologists that evaluated 50 MRI images in random order on 3 occasions.
Reliability was assessed by estimates of intraclass correlation coefficients.
|Intraclass correlation coefficients for intra-rater reliability of the modified Van Assche indices was 0.90|
|Alimentary Pharmacology & Therapeutics|
Common sources of disagreement were identified and recommendations made to minimize disagreement.
Intraclass correlation coefficients for intra-rater reliability of the original and modified Van Assche indices, and the VAS were 0.86, 0.90, and 0.86.
The team found that corresponding intraclass correlation coefficients for inter-rater reliability were 0.66, 0.67, and 0.58.
Sources of disagreement included number, location, and extension of fistula tracts, and rectal wall involvement.
The research team created a modified Van Assche index that included 7 component items.
Dr Jairath's team comments, "Although “almost perfect” intra-rater reliability was observed for the assessment of MRI images for fistulising Crohn's disease using the Van Assche index, inter-rater reliability was considerably lower."
"Our modification of this index should result in a more optimal instrument."