[1] Univ Chicago, Dept Med, 5841 S Maryland Ave, Chicago, IL 60637 USA
[2] Univ Chicago, Dept Pediat, Chicago, IL 60637 USA
[3] Northwestern Univ, Feinberg Sch Med, Stanley Manne Childrens Res Inst, Ann & Robert H Lurie Childrens Hosp, Chicago, IL 60611 USA
[4] Resp Hlth Assoc, Chicago, IL USA
[5] Chicago Dept Publ Hlth, Chicago, IL USA
[6] Univ Southern Calif, Keck Sch Med, Dept Prevent Med, Los Angeles, CA 90033 USA
[7] Northwestern Univ, Ann & Robert H Lurie Childrens Hosp, Chicago, IL 60611 USA
[8] Northwestern Univ, Feinberg Sch Med, Ann & Robert H Lurie Childrens Hosp, Sci & Outcomes Allergy & Asthma Res Program, Chicago, IL 60611 USA