1 Seattle Children's Research Institute, 2001 8th Ave Ste 400, Seattle, WA 98145-5005, United States. Electronic address: valeria.thompson@seattlechildrens.org.
2 Seattle Children's Research Institute, 2001 8th Ave Ste 400, Seattle, WA 98145-5005, United States; Department of Biostatistics, University of Washington, Seattle, WA, United States; Department of Pediatrics, University of Washington, 4800 Sand Point Way N.E., Box 5371, Seattle, WA 98105-0371, United States. Electronic address: nicole.hamblett@seattlechildrens.org.
3 Seattle Children's Research Institute, 2001 8th Ave Ste 400, Seattle, WA 98145-5005, United States. Electronic address: margaret.kloster@seattlechildrens.org.
4 Department of Respiratory Medicine, Royal Brompton Hospital, Sydney Street, London SW3 6NP, United Kingdom. Electronic address: d.bilton@rbht.nhs.uk.
5 Medical University of South Carolina, 96 Jonathan Lucas St., Room 812-CSB, Charleston, SC 29425, United States. Electronic address: flumepa@musc.edu.