Adult Onset Still Disease (AOSD) is an acquired inflammatory disease of unknown etiology, presenting with non specific symptoms. Its diagnosis rely on sets of criteria, i.e. Fautrel Criteria and Yamaguchi Criteria. However, differential diagnosis might appear during follow-up of patients. The aim of this study is to assess diagnostic performance of Fautral and Yamaguchi Criteria after 18 months of follow-up, and to describe differential diagnosis appearing during follow-up.

Adult Onset Still Disease (AOSD) is an acquired inflammatory disease of unknown etiology, presenting with non specific symptoms. Other conditions such as cancer, infection or other inflammatory disease might mimick its symptoms. Its diagnosis rely on sets of criteria, i.e. Fautrel Criteria and Yamaguchi Criteria. However, differential diagnosis might appear during follow-up after an initial diagnosis of AOSD. The aim of this study is to assess diagnostic performance of Fautral and Yamaguchi Criteria after 18 months of follow-up, and to describe differential diagnosis appearing during follow-up.

Inclusion Criteria:

• adults
• with glycosylated ferritin dosage for suspected adult onset still disease
• with at least 18 month of follow-up

Exclusion Criteria:

• known infectious disease
• known cancer
• known active connective tissue disease or vasculitis

Adult patients with suspected adult onset still disease with at least 18 months of follow-up.