Modifed Van Assche index calculator for perianal Crohn disease activity (MRI)

Note: this calculator returns the modified Van Assche index, which is not to be confused with the original scoring system.

Notes

• Unlike the original system, this modified formula gives weights to points in each category (thus the final score is not simply the sum of all points). The weights for each category are as follows:
  • Extension: x1.5
  • T2 hyperintensity: x2.3
  • Rectal wall involvement: x1
  • Inflammatory mass: x1.2
  • Dominant feature:x1.2
• Therefore the value of the modified Van Assche index ranges between 0-19.5.
• Collection size is categorized as follows:
  • Small: cavity 3-10 mm in diameter
  • Medium: 11-20 mm
  • Large: >20 mm
• Rectal wall thickening is defined as wall thickness >3 mm if the rectum is distended.
  • ^{Samaan MA, Puylaert CAJ, Levesque BG, Zou GY, Stitt L, Taylor SA, Shackelton LM, Vandervoort MK, Khanna R, Santillan C, Rimola J, Hindryckx P, Nio CY, Sandborn WJ, D’Haens G, Feagan BG, Jairath V, Stoker J. The development of a magnetic resonance imaging index for fistulising Crohn’s disease. Aliment Pharmacol Ther. 2017 Sep;46(5):516-528. doi: 10.1111/apt.14190. Epub 2017 Jun 27. PMID: 28653753.}
• Make sure to clearly indicate in the report whether the original or modified system has been used.
• According to one recent study (open access) clinical responders to anti-TNF therapy had a median modified Van Assche score of 9.6 (IQR 5.8–12.7) at baseline and 5.8 (IQR 3.5–8.5) during follow-up.
• In non-responders the scores were 7.7 (IQR 5.8–13.5) and 8.2 (IQR 5.8–11.5) respectively.
• As an important caveat about one third of clinical(!) responders showed no decrease in the imaging-based modified Van Assche score.
• Further changes to the scoring system are therefore likely necessary and to be expected.
  • ^{van Rijn KL, Lansdorp CA, Tielbeek JAW, Nio CY, Buskens CJ, D’Haens GRAM, Löwenberg M, Stoker J. Evaluation of the modified Van Assche index for assessing response to anti-TNF therapy with MRI in perianal fistulizing Crohn’s disease. Clin Imaging. 2020 Feb;59(2):179-187. doi: 10.1016/j.clinimag.2019.10.007. Epub 2019 Nov 22. PMID: 31821976.}

Last updated: 2021-08-18