Systemic onset juvenile idiopathic arthritis: clinical course

Favorable prognosis: The prognosis of systemic onset juvenile idiopathic ar thritis varies. The most favorable outcome is observed when joint involveme nt is mild or delayed. No initial clinical or biological feature is indicat ive of severe prognosis except polyarticular involvement at onset. There is no HLA association. After 10 years follow-up, inflammatory features have d isappeared in 50% of the cases, with some disability in 25%. Possible complications: Some severe complications can occur during the cour se of systemic juvenile idiopathic arthritis: secondary amyloidosis (1 to 2 %), spontaneous or drug-induced macrophage activation syndrome. cold salts, sulfasalazine, or nonsteroidal antiinflammatory drugs may be implicated, a ssociated or not with viral infection. Growth retardation is most often sec ondary to corticosteroid therapy. Longterm prognosis as published in variou s series mentions 8 to 14% mortality, secondary to iatrogenic accidents, in fections or secondary amyloidosis.