CRP and adult-onset Still disease: • The severity of the manifestations will influence the course of AOSD and outcomes. • Ferritin is a good predictor of aggressive disease in the short and long term. Patients with important articular disease are more likely to have a chronic disease. • Ferritin is associated with the occurrence of complications, and CRP the occurrence of complications and mortality. • CRP could be associated with articular erosions and progression to a chronic articular phenotype but is not validated on a large scale.