1. Pulmonology Department, Hospital de Braga, Braga, Portugal
2. Pulmonology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
3. Chest Disease Centre, Vila Nova de Gaia, Portugal
4. Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal
5. EpiUnit, Institute of Public Health, University of Porto, Porto, Portugal