1. Respiratory Department, Hospital Universitario Infanta Leonor, 28031 Madrid, Spain
2. Department of Public Health and Maternal & Child Health, Faculty of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain
3. Preventive Medicine and Public Health Teaching and Research Unit, Health Sciences Faculty, Universidad Rey Juan Carlos, 28933 Alcorcón, Spain
4. Epi-PHAAN Research Group, Instituto de Investigación Biomédica de Málaga (IBIMA), School of Medicine, Universidad de Málaga, 29071 Málaga, Spain
5. Respiratory Department, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Faculty of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain