[1] Univ Washington, Med Ctr, Dept Med, Div Pulm & Crit Care Med, Seattle, WA 98195 USA
[2] Univ British Columbia, Ctr Heart Lung Innovat, Vancouver, BC V5Z 1M9, Canada
[3] St Pauls Hosp, Vancouver, BC V6Z 1Y6, Canada
[4] Johns Hopkins Bloomberg Sch Publ Hlth, Baltimore, MD USA
[5] Seattle Childrens Hosp, Seattle, WA USA
[6] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[7] Univ Washington, Dept Pediat, Seattle, WA 98195 USA