1. Department of Respiratory Medicine, National Key Clinical Specialty, Branch of National Clinical Research Center for Respiratory Disease, Xiangya Hospital, Central South University, Changsha, Hunan, China
2. Hunan Provincial Clinical Research Center for Respiratory Diseases, Xiangya Hospital, Changsha, Hunan, China
3. National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Changsha, Hunan, China