[1] Ctr Dis Control & Prevent, Atlanta, GA USA
[2] Duke Univ, Med Ctr, Durham, NC USA
[3] Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA
[4] Univ N Carolina, Sch Med, Chapel Hill, NC USA
[5] Univ Kentucky, Coll Publ Hlth, Lexington, KY USA
[6] North Carolina Div Publ Hlth, Asthma Program, Raleigh, NC USA
[7] North Carolina Div Publ Hlth, State Ctr Hlth Stat, Raleigh, NC USA