Clinical Features and Outcome Measures Across Still's Disease (sJIA and AOSD) Cohorts Worldwide: A Systematic Literature Review.

OBJECTIVE Multinational research is essential to improve recognition and management of systemic juvenile idiopathic arthritis (sJIA). Current cohorts vary in the clinical parameters and outcome measures collected. sJIA and Adult-Onset Still's Disease (AOSD) are widely considered to comprise a single disease spectrum, however, classification criteria and clinical tools used differ between groups. This systematic literature review aimed to identify clinical features and outcome measures collected across sJIA and AOSD cohorts worldwide to guide development of a minimal dataset for Still's Disease. METHODS A literature search was conducted from 2000-2024 using OVID MEDLINE, Embase, and Wiley Cochrane Library (Trials). Included articles were in English and described sJIA or AOSD cohorts of ≥20 patients, reporting patient characteristics, clinical and laboratory features, and outcome measures. RESULTS 240 articles were included (95 sJIA, 134 AOSD, 11 mixed), from 37 countries, describing 23,136 patients. ILAR classification was used in 77.8% of sJIA studies, while 98.5% of AOSD studies used Yamaguchi criteria. There was no clear consensus on the definition of macrophage activation syndrome. Race and ethnicity were only reported in 11.7% of articles. Cohorts evaluated aligned on the most commonly collected laboratory items for both AOSD and sJIA, with some agreement among clinical features, while disease outcome measures used to evaluate and follow disease trajectory were variable. CONCLUSION Data reporting across sJIA and AOSD cohorts for clinical and outcome measures is widely heterogeneous. Consensus on identification of a standardized minimal dataset for Still's Disease cohorts is needed to foster future collaboration and improve patient outcomes.