[1] Hosp Clin Barcelona, Resp Inst, Barcelona 08036, Spain
[2] August Pi i Sunyer Biomed Res Inst IDIBAPS, Barcelona, Spain
[3] Univ Barcelona, Dept Med, Barcelona, Spain
[4] Inst Salud Carlos III, CIBER, Ctr Invest Biomed Red Enfermedades Resp, Madrid, Spain