1. Department of Pulmonary Diseases, Qilu Hospital, Shandong University, Jinan, Shandong, People's Republic of China;
2. Department of Respiratory Medicine, Northern Jiangsu People’s Hospital, Yangzhou, Jiangsu, People’s Republic of China;
3. Department of Respiratory Medicine, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong, People’s Republic of China