1 Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
2 Department of Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada.
3 Pulmonary, Critical Care, Allergy and Sleep Medicine, University of California, San Francisco, San Francisco, California.
4 Department of Respiratory and Sleep Medicine, Austin Hospital, Heidelberg, Victoria, Australia.
5 Lung Function & Sleep, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.
6 Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico.
7 Pulmonary Function Laboratory, Elliot Health System, Manchester, New Hampshire.
8 Pulmonary Disease and Critical Care Medicine, University of Vermont College of Medicine, Burlington, Vermont.
9 University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam.
10 Department of Paediatrics and Child Health, Faculty of Health Sciences, School of Clinical Medicine, University of Kwazulu-Natal, Durban, South Africa.
11 Division of Pulmonary and Critical Care, Johns Hopkins School of Medicine, Baltimore, Maryland; and.
12 Pulmonary Function Unit, Isala Hospital, Zwolle, the Netherlands.