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 address this gap, the Mucosal Inflammation Non-Invasive Index (MINI) was developed for pediatric Crohn's disease as part of the prospective international ImageKids study ³. It has since been validated across multiple independent cohorts and incorporated into clinical trials evaluating treatment response to exclusive enteral nutrition (EEN), whole-food dietary regimens (e.g., CDED, TASTI-E), anti-TNF agents, and vedolizumab ^4-18.

The MINI index incorporates stool frequency and character (derived from the PCDAI stool item), fecal calprotectin, ESR, and CRP in a weighted categorized index to identify children with endoscopic healing. A MINI score of <8 identifies endoscopic healing with 88% sensitivity and 85% specificity (AUC 0.92; 95% CI: 0.89–0.96), significantly outperforming fecal calprotectin alone ³. The likelihood of moderate-to-severe inflammation in patients with a MINI score of <8 is less than 5% ³.

The superiority of the MINI index over calprotectin alone has been confirmed in multiple independent pediatric studies:

EEN & Relapse Prediction: Herman et al. demonstrated high responsiveness of the MINI following EEN therapy, showing it predicted relapse with an area under the receiver operating characteristic curve (AUROC) of 0.90 (95% CI: 0.74–1.0), compared to 0.76 (95% CI: 0.57–0.95) for calprotectin alone ⁴.

Isolated Small Bowel Disease: In an Italian cohort, the MINI proved to be the most accurate non-invasive tool for isolated ileal disease—superior to both fecal calprotectin alone and wPCDAI—demonstrating a strong correlation with the Simple Endoscopic Score for Crohn's Disease (SES-CD; r = 0.73) ⁵.

Endoscopic Healing Cutoffs: A validation study from Barcelona demonstrated excellent prediction of endoscopic healing with an AUC of 0.985 (p < .001) using a MINI cutoff of <6 ⁶.

Biologic Response: In the prospective VEDOKIDS trial, the MINI was the strongest predictor of response to vedolizumab in children with Crohn's disease (AUC 0.79 [95% CI: 0.64-0.94]) ⁸. In addition, multi-center studies evaluating anti-TNF therapy demonstrated that 62% of children achieved mucosal healing (MINI $<8$) at 12 weeks, with MINI-defined response mirroring distinct shifts in the gut microbiome and metabolome ¹².

Proactive Monitoring & Dietary Trials: Long-term pediatric studies have utilized the MINI index during proactive drug monitoring and prospective dietary trials (CDED, EEN, and whole-food regimens) to confirm sustained mucosal response and treatment durability non-invasively ^9,13,15,17.

Extrapolation & Position Statements: Given its robust non-invasive performance, the MINI index features prominently in international consensus recommendations (ESPGHAN-NASPGHAN) and review frameworks aimed at streamlining pediatric IBD drug approval and long-term monitoring ^9,18.