MINI Index

MINI Index (Mucosal Inflammation Noninvasive index)
Aim: to estimate the degree of mucosal inflammation in Crohn’s disease non-invasively

Both the original PCDAI and its mathematically weighted version (wPCDAI) have insufficient correlation with endoscopic activity (r=0.33-0.45)^1,2. To that end, as part of the prospective ImageKids study, the Mucosal Inflammation Non-Invasive Index (MINI) was developed for pediatric CD³. It has been validated in several independent cohorts and incorporated in studies evaluating treatment response, such as exclusive enteral nutrition (EEN) and Anti-TNF regimens and vedolizumab ^4-8. 

The MINI index incorporates stool frequency and character (the stool item from the PCDAI), fecal calprotectin, ESR, and CRP in a weighted categorized index to identify children with endoscopic healing. A MINI score of <8 identified children with endoscopic healing with 88% sensitivity and 85% specificity (AUC 0.92; 95% CI 0.89-0.96), which was superior to the measurement of fecal calprotectin alone³. The likelihood of moderate-severe inflammation with a MINI score of <8 was <5%.

The superiority of the MINI index over calprotectin alone has since been demonstrated in independent pediatric studies. Herman et al. showed that the MINI had high responsiveness following treatment with EEN and that it predicted relapse with an area under the receiver operating curve (AUROC) of 0.90 (95% CI 0.74-1.0) vs. only 0.76 (0.57-0.95) with calprotectin⁴. In an Italian study, the MINI was found to be the most accurate non-invasive tool for isolated ileal disease, superior to fecal calprotectin alone and wPCDAI, with a strong correlation to SES-CD (r=0.73)⁵. A study from Barcelona demonstrated excellent prediction of endoscopic healing with an AUC of 0.985 (p<0.001) using a MINI cutoff of <6⁶. In the VEDOKIDS prospective study, the MINI was the strongest predictor of response to vedolizumab in children with CD (AUC 0.79 (95% CI 0.64-0.94))⁸. In another pediatric study, the MINI index was used to assess rate of mucosal healing 12 weeks after initiating anti-TNF in children with Crohn’s disease in association with microbial and metabolomics changes; 62% of children achieved mucosal healing as defined by MINI index <8 ⁷. Lending further support to the validity of the MINI index, the reaction of the microbiome after treatment differed between responders based on the MINI index and non-responders⁷. Response to anti-TNF was assessed over time by the MINI index in other pediatric studies, reflecting long term durability and effectiveness of the drug ⁹.