Unmet needs and research gaps in Still's disease across ages: proceedings from a pediatric and adult joint expert panel.

Background: Still's disease (SD), including systemic juvenile idiopathic arthritis (sJIA) and adult-onset SD (AOSD), is an inflammatory condition typically characterized by daily fever, arthritis, and skin rash together with neutrophilic leukocytosis, thrombocytosis, and increased acute phase reactants. The reported differences between sJIA and AOSD appear to reflect variations along an inflammatory spectrum influenced by age, rather than differences in the underlying pathology.

Methods: In February 2023, an expert meeting, including pediatric and adult rheumatologists, was held in Rome, Italy, with the aim of defining more precise and timely strategies for disease management. The following four topics were discussed: (1) early recognition and diagnosis of SD; (2) pathogenetic pathways and possible biomarkers for diagnosis and response; (3) refractory disease and risk factors, and (4) treatment of SD and its complications.

Results: The development of improved diagnostic criteria and validation of biomarkers are important steps towards achieving early diagnosis, although several biomarkers remain to be universally validated and available for clinical practice. Additionally, awareness of important complications of SD, including macrophage activation syndrome and lung disease, is crucial for improving patient outcomes, alongside an improved understanding of risk factors for the development of refractory disease. While interleukin (IL)-1 and IL-6 inhibitors have improved the treatment landscape of SD, harmonizing the therapeutic approach across centers and countries, together with developing treatment strategies for refractory patients, still represents a challenge.

Conclusions: Here, we summarize the results of discussions among experts, supplemented by relevant literature, and highlight unmet needs in the diagnosis and management of SD.