1 Pulmonary Section, San Pedro de Alcántara Hospital, Cáceres, Spain; CIBER de enfermedades respiratorias (CIBERES), Madrid, Spain. Electronic address: fmasa@separ.es.
2 Pulmonary Section, San Pedro de Alcántara Hospital, Cáceres, Spain; CIBER de enfermedades respiratorias (CIBERES), Madrid, Spain.
3 Pulmonary Section, Virgen del Puerto Hospital, Plasencia, Spain.
4 Department of Medicine, Section of Pulmonary and Critical Care, University of Chicago, Chicago, IL.