1. National Heart and Lung Institute, Imperial College London, London SW3 6LY, UK
2. Oncology Division, CHU de Québec-Université Laval Research Center, Québec City, QC G1R 3S3, Canada
3. Department of Social and Preventive Medicine, Faculty of Medicine, Université Laval, Québec City, QC G1V 0A6, Canada
4. Department of Applied Health Research, University College London (UCL), London WC1E 7HB, UK