[1] Univ Illinois, Coll Med, Dept Med, Peoria, IL 61656 USA
[2] Univ Utrecht, Med Ctr, Dept Rheumatol & Clin Immunol, NL-3508 GA Utrecht, Netherlands
[3] St Bartholomews & Royal London Hosp, Sch Med & Dent, Bone & Joint Res Unit, London EC1M 6BQ, England
[4] Univ Genoa, Dept Internal Med, Div Rheumatol, I-16136 Genoa, Italy