[1] Childrens Hosp Philadelphia, Div Rheumatol, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Ctr Pediat Clin Effectiveness, Res Inst, 2716 South St,11th Floor, Philadelphia, PA 19146 USA
[3] Univ Penn, Dept Pediat, Perelman Sch Med, Philadelphia, PA 19104 USA
[4] Univ Penn, Dept Biostat Epidemiol & Informat, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Childrens Hosp Philadelphia, Off Clin Qual Improvement, Philadelphia, PA 19104 USA
[6] Univ Penn, Ctr Pharmacoepidemiol Res & Training, Philadelphia, PA 19146 USA