1. Liverpool Centre for Cardiovascular Science at University of Liverpool, Liverpool John Moores University and Liverpool Heart & Chest Hospital, Liverpool, United Kingdom;
2. Department of General and Specialized Surgery, Sapienza University of Rome, Rome, Italy;
3. Knowsley Community Respiratory Service and
4. Respiratory Department, Liverpool Heart & Chest Hospital NHS Foundation Trust, Liverpool, United Kingdom;
5. Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom; and
6. Danish Center for Health Services Research, Department of Clinical Medicine, Aalborg University, Aalborg, Denmark