[1] IRYCIS, Hosp Ramon y Cajal, Resp Dept, Madrid 28034, Spain
[2] Txagorritxu Hosp, Resp Dept, Vitoria, Spain
[3] Hosp Badalona Germans Trias & Pujol, Dept Med, Badalona, Spain
[4] Uniformed Serv Univ Hlth Sci, F Edward Hebert Sch Med, Bethesda, MD 20814 USA
[5] Galdakao Hosp, Resp Dept, Galdakao, Spain
[6] San Pedro Hosp, Resp Dept, Logrono, Spain
[7] Virgen del Rocio Hosp, Resp Dept, Seville, Spain
[8] La Fe Hosp, Resp Dept, Valencia, Spain
[9] Hosp Xeral Calde, Dept Med, Lugo, Spain
[10] Hosp Sierrallana, Dept Med, Cantabria, Spain
[11] Hosp Parc Tauli, Dept Med, Sabadell, Spain
[12] Hosp San Juan Dios, Resp Dept, Seville, Spain
[13] Univ Oviedo, Hosp Cent Asturias, Resp Dept, E-33080 Oviedo, Spain
[14] Hosp Lozano Blesa, Resp Dept, Zaragoza, Spain
[15] Hosp Cruces, Resp Dept, Bilbao, Spain
[16] Univ Hosp Bern, Div Gen Internal Med, CH-3010 Bern, Switzerland
[17] Washington Univ, Sch Med, Div Pulm & Crit Care Med, St Louis, MO USA
[18] Washington Univ, Sch Med, Div Gen Med Sci, St Louis, MO USA