[1] Vanderbilt Univ, Sch Med, Dept Med, Div Allergy Pulm & Crit Care Med, Nashville, TN 37235 USA
[2] Vanderbilt Univ, Sch Med, Dept Biostat, Nashville, TN 37235 USA
[3] Vanderbilt Univ, Sch Med, Ctr Asthma & Environm Hlth Res, Nashville, TN 37235 USA
[4] Vanderbilt Univ, Sch Med, Dept Pediat, Nashville, TN 37235 USA
[5] Vanderbilt Univ, Sch Med, Dept Emergency Med, Nashville, TN 37235 USA