[1] Childrens Hosp Philadelphia, Dept Pediat, Philadelphia, PA 19104 USA
[2] Univ Penn, Childrens Hosp Philadelphia, Perelman Sch Med, Dept Pediat,Div Rheumatol & Clin Futures, Philadelphia, PA USA
[3] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Philadelphia, PA USA
[4] Baylor Coll Med, Dept Pediat, Div Rheumatol, 1102 Bates Ave,Suite 330, Houston, TX 77030 USA
[5] Texas Childrens Hosp, 1102 Bates Ave,Suite 330, Houston, TX 77030 USA