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