P273 Defining the prognosis of children with Crohn Disease with the support of magnetic resonance enterography: a multi-center multi-reader study

Abstract

Abstract Background Ileocolonoscopic assessment is the most accurate method for detecting intestinal inflammation in Crohn disease (CD), but it allows the assessment only of a limited tract of the small intestine and does not provide data on inflammation beyond the mucosa. The auxiliary use of magnetic resonance enterography (MRE) can overcome these limitations and allow to predict the course of CD. Paediatric Inflammatory Crohn's MRE Index (PICMI) is a multi-point index of intestinal inflammation (mucosal and transmural) in children with CD created on the basis of MRI. The aim of the present study is to assess whether this completely non-invasive index at diagnosis could predict the course of CD in children and to test the inter-reader agreement as surrogate of index reproducibility. Methods All children diagnosed with CD in two tertiary referral centres with a 1-year minimum follow-up were enrolled in the study. MRE at diagnosis was blindly evaluated by 3 expert radiologists and PICMI was calculated for all patients. Children’s disease was stratified according to PICMI at diagnosis into remission (<10), mild (11-55), moderate (56-120) and severe (>120). Inter-observer agreement among radiologist was calculated. Data at follow-up were collected at 6-8 weeks, 1 year, 3 years and 5 years after CD diagnosis. Association between PICMI at diagnosis and CD prognosis was evaluated. Results A total of 71 children (52 males) with proven CD were enrolled in the study and PICMI was calculated for 68. PICMI at diagnosis was stratified into remission 6 (8.8%), mild 29 (42.6%), moderate 24 (35.3%), severe 9 (13.2%). Inter-observer agreement was calculated with an intraclass correlation coefficient of 0.65 which indicates moderate reliability between the 3 raters. PICMI score at diagnosis significantly correlated with PCDAI (Paediatric Crohn's Disease Activity Index) at diagnosis (p: 0.036). Steroid-free remission at 1, 3 and 5 years was comparable between PICMI groups: remission + mild vs moderate + severe (p: 0.606). CRP and calprotectin negative steroid free remission at 1,3,5 was also comparable (p: 0.578). PICMI at diagnosis was associated with the probability of biologic introduction at 1 year: incidence rate ratio IRR: 2.17 (1.09-4.42); p=0.019, 3-year IRR: 2.12 (1.15-3.96); p=0.011, and 5 years: 2.21 (1.20-4.08); p=0.007 (figure 1). Conclusion PICMI score is a reliable and reproducible index to determine activity in children with Crohn’s disease. Children with more active disease at diagnosis according to PICMI have shown an increased need to progression to biologic treatment in order to gain a comparable rate of steroid free remission and inflammatory marker negativity if compared with children with lower PICMI scores.