[1] Univ Calif San Diego, Dept Pediat, La Jolla, CA 92093 USA
[2] Univ Calif San Diego, Dept Family Med & Publ Hlth, La Jolla, CA 92093 USA
[3] Boston Univ, Slone Epidemiol Ctr, Boston, MA 02215 USA
[4] Kaiser Permanente, Dept Allergy & Immunol, San Diego, CA USA
[5] Amer Acad Allergy Asthma & Immunol, Milwaukee, WI USA