[1] Copenhagen Univ Hosp, Dept Rheumatol, Parker Inst, Musculoskeletal Stat Unit, Bispebjerg, Denmark
[2] Copenhagen Univ Hosp, Dept Rheumatol, Parker Inst, Musculoskeletal Stat Unit, Frederiksberg, Denmark
[3] Tel Aviv Univ, Sackler Fac Med, Schneider Childrens Med Ctr Israel, Pediat Rheumatol Unit, IL-69978 Tel Aviv, Israel
[4] Klinikum Eilbek, Hamburger Zentrum Kinder & Jugend Rheumatol, Hamburg, Germany
[5] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90095 USA