The systemic score may identify life-threatening evolution in Still's disease: data from the GIRRCS AOSD-study group and the AIDA Network Still's Disease Registry

Objectives: To evaluate the clinical usefulness of the systemic score in the prediction of life-threatening evolution in Still's disease. To assess the clinical relevance of each component of the systemic score in predicting life-threatening evolution and to derive patient subsets accordingly. Methods: A multicenter, observational, prospective study was designed including patients included in the GIRRCS (Gruppo Italiano Di Ricerca in Reumatologia Clinica e Sperimentale) AOSD-study group and AIDA (AutoInflammatory Disease Alliance) Network Still's Disease Registry. Patients were assessed if variables to derive the systemic score were available. The life-threatening evolution was defined as mortality, whichever the clinical course, and/or macrophage activation syndrome (MAS), a secondary hemophagocytic lymphohistiocytosis associated with a poor prognosis. Results: Totally 597 patients with Still's disease were assessed (age 36.6±17.3 years; male 44.4%). The systemic score, assessed as continuous variable, significantly predicted the life-threatening evolution (OR: 1.24, 95%CI:1.07-1.42; p=0.004). A systemic score ≥7 also significantly predicted the likelihood of a patient experiencing life-threatening evolution (OR: 3.36, 95%CI:1.81-6.25; p<0.001). Assessing the clinical relevance of each component of the systemic score, liver involvement (OR: 1.68, 95%CI:1.48-2.67; p=0.031) and lung disease (OR: 2.12, 95%CI:1.14-4.49; p=0.042) both significantly predicted life-threatening evolution. The clinical characteristics of patients with liver involvement and lung disease were derived, highlighting their relevance in multiorgan disease manifestations. Conclusion: The clinical utility of the systemic score was shown in identifying Still's disease at higher risk of life-threatening evolution in a large cohort. Furthermore, the clinical relevance of liver involvement and lung disease was highlighted.