Clinical Usefulness of the MINI (Mucosal Inflammation Noninvasive Index) Score as a Non-Invasive Indicator for Assessing Mucosal Healing in Pediatric Patients with Crohn’s Disease

<b>Background/Objectives:</b> The primary goal of Crohn's disease (CD) treatment is to achieve mucosal healing (MH). The best test to assess the effectiveness of therapy is endoscopic examination of the gastrointestinal (GI) tract, which is an invasive examination associated with a potentially high risk of complications resulting from the examination technique itself and the general anesthesia procedure. Previously used noninvasive methods for assessing the activity of CD show an unsatisfactory correlation with the severity of endoscopic lesions. There is a need to develop new, noninvasive indicators of the severity of inflammatory lesions in the GI tract in the course of CD. The aim of the study was to assess the clinical usefulness of the Mucosal Inflammation Noninvasive Index (MINI) as a noninvasive indicator of MH in pediatric patients with CD. <b>Methods</b>: The study included 199 children with CD who underwent endoscopic examinations of the upper and lower GI tract. The study group consisted of both patients with a diagnosis of CD and those whose indication for esophagogastroduodenoscopy and colonoscopy was a suspicion of inflammatory bowel disease. The clinical activity of CD was assessed using the Pediatric Crohn's Disease Clinical Activity Index-PCDAI, and the severity of endoscopic inflammatory lesions was assessed using the simplified scale of endoscopic Crohn's disease activity-SES-CD. The study assessed the correlation between the results of laboratory tests, PCDAI, SES-CD, and MINI. <b>Results</b>: In the study group positive correlation was found between MINI and PCDAI (r = 0.52, <i>p</i> < 0.001) and between MINI and SES-CD (r = 0.54, <i>p</i> < 0.001). A MINI score of 15 points or more indicated severe CD, defined as SES-CD ≥ 16 points, with a diagnostic sensitivity of 86% and specificity of 89%. Additionally, MINI was shown to be positively correlated with white blood cell count (WBC; r = 0.39, <i>p</i> < 0.001) and platelet count (PLT; r = 0.59, <i>p</i> = 0.007). <b>Conclusions</b>: MINI shows moderate correlation with endoscopic and clinical indices and may serve as a complementary, non-invasive marker for the assessment of MH in pediatric CD. Additional advantages of MINI are non-invasiveness, objectivity, and simplicity.