Clinical characteristics
Clinical characteristics of the 17 SLE patients at the time of SF sampling are summarized in Table 1. The patients were fairly representative of a typical SLE population. Samples were collected at a time of long disease history including long standing arthritis, often polyarticular and which had occurred among the first disease manifestations. Six of the patients (age at onset 28y, IQR 17-38) had developed secondary knee osteoarthritis over time.