1. Service of Pneumology, Hospital de la Santa Creu i Sant Pau, Universitat Autonoma de Barcelona, Barcelona, Spain.
2. Service of Clinical Epidemiology, Hospital General de Vic, c/ Francesc Pla, 1, Vic, Spain.
3. Health Centre France I. C/, Francia 38, Posterior, Fuenlabrada (Madrid), Spain.
4. Service of Pneumology, Hospital Clinico San Carlos, Universidad Complutense de Madrid, C/ Martin Lagos s/n, Madrid, Spain.
5. Department of Allergy, Hospital la Paz Health Research Institute (IdiPAZ), Madrid, Spain.
6. Complejo Asistencial Universitario de Burgos, Burgos, Spain.
7. School of Medicine, Universidad Francisco de Vitoria, Pozuelo de Alarcón (Madrid), Spain.
8. Medical Advisor of Medical Department Chiesi Spain, L'Hospitalet de Llobregat, Barcelona, Spain.