Identifying outcome measures for clinical trials in juvenile idiopathic arthritis associated uveitis for the MIWGUC proposal: a scoping review to create domains from existing outcome measures

Chronic anterior uveitis represents the most important extra-articular manifestation of Juvenile Idiopathic Arthritis (JIA). Previous reviews have shown that outcome measures for this condition are widely heterogeneous. Therefore, our aim was to update the 2019 systematic literature review and to identify similarities, differences, and emerging outcome domains reported over the subsequent five years. We performed a systematic literature review from 1st January 2019 to 28th February 2025 to identify studies investigating outcome measures used in JIA-associated uveitis (JIA-U), according to PRISMA guidelines. We identified 261 papers, of whom 90 potentially eligible. After the full-text revision, 37 studies plus the previous 27, including 1 randomized clinical trial (RCT), were included. Among these studies, 15 outcome measures for JIA-U were identified. Based on their characteristics, we categorized them into three different subgroups: outcome measures for disease activity (30 studies); outcome measures correlated to structural damage (29 studies); and outcome measures of severe disease course (20 studies). The most frequent outcome measures used were the assessment of anterior chamber (AC) cells (29 studies), the visual acuity (21 studies), the development of structural complications (20 studies) and the use and sparing of immunosuppressive therapies (15 studies). Compared with the 2019 review, we identified four studies reporting novel objective techniques for inflammation assessment, including laser flare photometry and anterior segment optical coherence tomography. Our review confirms the variety of outcome measures for JIA-U while highlighting the emergence of novel imaging and biomarker-based measures. These findings provide an updated evidence base for revising the core outcome set and emphasize the urgent need for a consensus and a composite score, which are essential both for designing endpoints in clinical trials and for guiding treatment choices in clinical practice.