[1] Seattle Childrens Hosp, Cyst Fibrosis Fdn, Therapeut Dev Network Coordinating Ctr, Seattle, WA 98105 USA
[2] Univ Washington, Dept Pediat, Seattle, WA 98195 USA
[3] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[4] Univ Washington, Dept Med, Seattle, WA USA
[5] Univ N Carolina, Div Pediat Pulmonol, Chapel Hill, NC 27515 USA
[6] Cyst Fibrosis Fdn, Bethesda, MD USA
[7] Washington Univ, Sch Med, Div Pulm & Crit Care Med, St Louis, MO USA