Patients with Adult-Onset Still’s Disease in Germany: A Retrospective Analysis of Clinical Characteristics and Treatment Practices Ahead of the Release of the German Recommendations

<b>Background/Objectives:</b> Adult-onset Still's disease (AOSD) is an autoinflammatory disorder that can be challenging to diagnose and manage. The aim of this study was to analyze retrospective data to provide insights into the clinical presentation, disease activity, and treatment patterns and outcomes of AOSD during routine clinical care prior to the release of new AOSD guidelines. <b>Methods:</b> This retrospective database analysis evaluated adult patients (≥18 years) with a diagnosis of AOSD who engaged in a clinical visit between 1 January 2010 and 31 December 2020. The evaluated outcomes included demographic characteristics, symptoms, disease activity, and treatment. <b>Results:</b> Our study included 120 patients (67 [55.8%] of whom were female) diagnosed with AOSD according to the Yamaguchi criteria at ten German rheumatology centers. The median (quartile [Q] 1, Q3) age was 51 (36, 62) years, and the median (Q1, Q3) time from diagnosis was 9 (4, 11) years. Approximately half (66 [55.0%]) had a polycyclic disease course. The most frequent symptoms at initial diagnosis were arthralgia (105 [87.5%]) and fever (86 [71.7%]), and these symptoms continued for a substantial proportion of patients at the current visit (35 [29.2%] and 22 [18.3%], respectively). High neutrophil and ferritin levels were also common. The mean Still Activity Score, a measure of disease activity, improved from 4.66 at initial diagnosis to 1.97 at the most recent visit. The treatments most frequently used at some point in the disease course were glucocorticoids (118 [98.3%]), interleukin (IL)-1 inhibitors (89 [74.2%]), and methotrexate (85 [70.8%]). The most common current treatments were IL-1 inhibitors (55 [45.8%]), followed by methotrexate (29 [24.2%}) and glucocorticoids (28 [23.3%]). <b>Conclusions:</b> Our cohort of patients with AOSD seen at German rheumatology clinics showed strong improvements in symptoms and disease activity from initial diagnosis, but a high symptom burden remained for some patients. Future studies may be able to build on our data to document the impact of new guidelines on treatment patterns.