1 Department of Medicine, Respiratory Investigation Unit, Laboratory of Clinical Exercise Physiology, Kingston General Hospital, Queen's University, Kingston, Ontario, Canada.
2 Department of Public Health and Infectious Diseases, Adult Cystic Fibrosis Center, Sapienza University of Rome, Rome, Italy.
3 Adult Cystic Fibrosis Center, Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom.