[1] Hosp Univ Severo Ochoa, Madrid, Spain
[2] IRCCS Osped Pediat Bambino Gesu, Rome, Italy
[3] Hosp Univ Infanta Sofia, Madrid, Spain
[4] Cincinnati Childrens Hosp Med Ctr, Cincinnati, OH 45229 USA
[5] Emory Univ, Childrens Hlth Care Atlanta, Atlanta, GA 30322 USA
[6] Ist Giannina Gaslini, Genoa, Italy
[7] Hosp Univ Ramon & Cajal, Madrid, Spain
[8] MC Grp, Lelystad, Netherlands
[9] Fiona Stanley Hosp Unit, Sch Med & Pharmacol, Perth, WA, Australia
[10] Univ Copenhagen, Glostrup Hosp, Ctr Rheumatol & Spine Dis, Copenhagen, Denmark