1. Department of Pulmonary and Critical Care Medicine, Second Xiangya Hospital; Research Unit of Respiratory Disease; Diagnosis and Treatment Centre of Respiratory Disease, Central South University, Changsha, Hunan, China
2. Clinical Medical Research Centre for Respiratory and Critical Care Medicine in Hunan Province, China
3. Department of Pulmonary and Critical Care Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China
4. Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China
5. Department of Respiratory Medicine, The First Affiliated People's Hospital, Shaoyang College, Shaoyang, Hunan, China