Development of a scoring system to assist clinicians in the early referral of patients with suspected juvenile idiopathic arthritis: the EasyJIA score

OBJECTIVE: Juvenile idiopathic arthritis (JIA) is the most common chronic pediatric rheumatic disease. Early referral to a specialized center is crucial for prompt diagnosis and treatment. This study aims to develop and validate a scoring system to assist clinicians in efficiently identifying and referring patients suspected of having non-systemic JIA. METHODS: We conducted a cohort study with a mixed design (retrospective and prospective), involving consecutive patients presenting with joint complaints who were referred for the first time to the Pediatric Rheumatology Unit at ASST G. Pini-CTO Hospital. The model was developed using multivariate logistic regression with bootstrap resampling and the Lasso (Least Absolute Shrinkage and Selection Operator) method for variable selection. RESULTS: A total of 342 patients were included, of whom 61 (18%) were diagnosed with JIA. The selected variables for the model were: type of joint (large), daily symptoms, joint swelling, activity as a precipitating factor, a positive squeeze test of the metatarsophalangeal/metacarpophalangeal (MTP/MCP) joints, normal bending of the interphalangeal (IF) joints of the hands, morning limping and/or stiffness, and sacroiliac tenderness. The ROC curve, based on the model's regression score, showed an AUC of 0.92 with an overall accuracy of 0.88 (95% CI: 0.84-0.91) using a cutoff of 3 points, yielding a sensitivity of 95% and a specificity of 71%. Initial internal validation of the model revealed an AUC of 0.92 (95% CI: 0.89-0.95). CONCLUSION: This study presents and initially validates a simple and efficient scoring system to aid clinicians in the early referral of patients suspected of having non-systemic JIA. CLINICAL TRIAL NUMBER: Not applicable.