Overview of adult-onset Still disease
Adult-onset Still disease is a rare autoinflammatory disorder of unknown aetiology with multisystem involvement. It is considered an autoinflammatory disease because of its characteristic autoinflammatory features, in the absence of detectable autoantibodies (eg antinuclear antibodies [ANA]). The autoinflammatory response is driven by cytokines, macrophages and neutrophils, which is different to autoimmune (antibody-mediated) conditions such as rheumatoid arthritis.The hallmark of the autoinflammatory response is a ‘cytokine storm’, characterised by excessive production of various interleukins, tumour necrosis factor (TNF) and other cytokines.
Adult-onset Still disease shares clinical and laboratory similarities with systemic juvenile idiopathic arthritis (JIA), but the term ‘adult-onset’ applies if the disease first presents at 16 years or older, typically in early adulthood. For more details on systemic JIA, see the separate topic.
The prevalence of adult-onset Still disease is equal in males and females.
Adult-onset Still disease may have a variable clinical course, includingGiacomelli, 2018:
- a monophasic course—limited to a single episode; complete remission (with or without treatment) is achieved within a couple of weeks or months
- a recurrent course—characterised by relapse(s) following either months or years of immunomodulatory therapy or discontinuation of therapy; a first episode can occur in childhood (ie systemic JIA), followed by several years of drug-free remission; a relapse in adulthood is then classified adult-onset Still disease
- a chronic and progressive course—the most frequent type, in about 35 to 57% of affected peopleTomaras, 2021; continuous inflammation is associated with chronic erosive arthritis and regular episodes of systemic symptoms (see Clinical features of adult-onset Still disease).
People with adult-onset Still disease may be well between episodes of fever or have some residual symptoms (eg joint pain).