Assessment of the Reliability of Outcome Measures in Rheumatology (OMERACT) Juvenile Idiopathic Arthritis Magnetic Resonance Imaging Scoring System for Sacroiliac Joint (JAMRIS SIJ)

Objectives Outcome measures in Rheumatology (OMERACT) Juvenile Idiopathic Arthritis MRI Score in the sacroiliac joint (JAMRIS-SIJ) have been developed by the Rheumatoid Arthritis Study Group for the need for a standardized evaluation of SIJ in children. This study aims to evaluate the interrater reliability of JAMRIS SIJ. Methods Patients younger than 18 years with a diagnosis of enthesitis-related arthritis and who had a sacroiliac MRI scan between October 2014 and December 2023 were enrolled in the study. Demographic data of the patients were recorded from clinical charts. Five raters examined the MRI scans and JAMRIS SIJ scores were recorded. Interrater reliability was assessed with intraclass correlation coefficient. Results The study comprised 40 MRI examinations of 31 patients. Fifteen of 31 patients were female. The median age at referral for scanning was 14,4 years. The intraclass correlation coefficient was 0.870 (0.780-0.935) (p < 0.001) and 0.654(0.473-0.791) (p < 0.001); for the inflammation and structural damage domains, respectively. Bone marrow edema had the highest interrater reliability (ICC= 0.910 (0.863-0.946) (p < 0.001)) from all components evaluated in JAMRIS-SIJ, and fat lesion had the highest interrater reliability (intraclass correlation coefficient= 0.764 (0.648-0.855) (p < 0.001)) from structural damage components. Conclusions Our results indicate that JAMRIS SIJ is reliable in evaluating most inflammation and structural damage components. JAMRIS SIJ may be used as a quantitative guide for the therapeutic management of patients with JIA. Advances in knowledge Juvenile Idiopathic Arthritis Magnetic Resonance Imaging Scoring System for Sacroiliac Joint is a reliable tool for evaluating inflammatory and structural damage components of sacroiliitis.