To define different clinical phenotypes and assess prognostic factors of adult-onset Still's disease (AOSD).
Overall, 492 patients with AOSD seen between 2004 and 2018 at a single centre were retrospectively studied.
Of these patients, 78% were female, and the median age at onset was 34 (25-49) years [median (25th-75th percentile)]. The median follow-up time was 7 (3-10) years [median (25th-75th percentile)]. Clinical manifestations at admission were used to subdivide patients with AOSD as follows: systemic inflammation (cluster 1), pure (cluster 2), and intermediate (cluster 3). Each subtype had distinct clinical manifestations and prognoses: cluster 1 (34.6%)-multiple organ manifestations, highest infection rate and mortality, and more than half of the patients with at least one relapse during follow-up; cluster 2 (21.3%)-exclusively female, rash and joint involvement, no internal organ involvement, no mortality, and most of the patients with a monocyclic course; and cluster 3 (44.1%)-less infection rate, no serious complications, and lower mortality rate. The 5- and 10-year survival rates after diagnosis were 92.4% and 86.9%, respectively. Independent risk factors for mortality were age at onset ≥50 (hazard ratio (HR): 6.78, 95% CI: 2.10-21.89), hepatomegaly (HR: 5.05, 95% CI: 1.44-17.70), infection (HR: 15.56, 95% CI: 5.88-41.20), and MAS (HR: 26.82, 95% CI: 7.52-95.60).
Three subtypes of AOSD were identified with distinct clinical manifestations and prognoses. Age at onset ≥50, hepatomegaly, infection, and MAS were prognostic factors for AOSD mortality.