[1] Alder Hey Childrens NHS Fdn Trust, Liverpool, Merseyside, England
[2] Univ Liverpool, Dept Biostat, MRC North West Hub Trials Methodol Res, Liverpool L69 3BX, Merseyside, England
[3] UCL, Sect UCL Inst Child Hlth, Infect Immunol & Rheumatol, London, England
[4] Great Ormond St Hosp NHS Fdn Trust, London, England
[5] UCL, Univ Coll London Hosp, Ctr Adolescent Rheumatol, London, England
[6] IWK Hlth Ctr, Halifax, NS B3K 6R8, Canada
[7] Dalhousie Univ, Halifax, NS B3K 6R8, Canada
[8] Univ Genoa, I-16147 Genoa, Italy
[9] Ist Giannina Gaslini, I-16147 Genoa, Italy
[10] Univ Liverpool, Inst Translat Med, Dept Womens & Childrens Hlth, Liverpool L69 3BX, Merseyside, England