[1] Ramon & Cajal Hosp, Resp & Med Dept, Madrid, Spain
[2] Alcala de Henares Univ, Madrid, Spain
[3] Univ Lausanne, Div Gen Internal Med, Lausanne, Switzerland
[4] Uniformed Serv Univ Hlth Sci, F Edward Hebert Sch Med, Bethesda, MD 20814 USA
[5] Txagorritxu Hosp, Resp Dept, Vitoria, Spain
[6] Cruces Hosp, Resp Dept, Bilbao, Spain
[7] Virgen del Rocio Hosp, Resp Dept, Seville, Spain
[8] Germans Trias & Pujol Hosp, Div Gen Internal Med, Badalona, Spain
[9] Washington Univ, Sch Med, Div Pulm & Crit Care Med, St Louis, MO USA
[10] Washington Univ, Sch Med, Div Gen Med Sci, St Louis, MO USA