[1] Univ Alcala Henares, Inst Ramon Y Cajal Invest Sanitaria, Dept Resp Med, Ctra Colmenar Viejo,Km 9,100, Madrid, Spain
[2] Univ Complutense Madrid, Hosp Univ 12 Octubre, Inst Hlth Res I 12, Dept Resp Med, Madrid, Spain
[3] Univ Autonoma Madrid, Hosp Univ Puerta Hierro, Dept Resp Med, Majadahonda, Spain
[4] Univ Autonoma Madrid, Hosp Univ Princesa, Dept Resp Med, Madrid, Spain
[5] Univ Lugo, Hosp Univ Lucus Augusti, Dept Resp Med, Lugo, Spain
[6] Autonoma Univ Barcelona, Dept Resp Med, Hosp Santa Creu & St Pau Inst, Inst Invest Biomed St Pau, Barcelona, Spain
[7] Laredo Hosp, Dept Resp Med, Laredo, Spain
[8] Univ Cordoba, Hosp Univ Reina Sofia, Dept Resp Med, Cordoba, Spain
[9] Univ Salamanca, Hosp Univ Salamanca, Dept Resp Med, Salamanca, Spain
[10] Univ Oviedo, Hosp Univ Cent Asturias, Dept Resp Med, Oviedo, Spain
[11] Fdn Jimenez Diaz, Dept Hlth Informat Management, Madrid, Spain
[12] Univ Alcala Henares, Consorcio Ctr Invest Biomed Red Epidemiol & Salud, Inst Ramon Y Cajal Invest Sanitaria, Unit Clin Biostat, Madrid, Spain