1. Department of Geriatric Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, China.
2. Department of Respiratory Medicine, The Sixth Affiliated Hospital of Guangxi Medical University, Yulin, China.
3. Department of Respiratory Medicine, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China.
4. The Graduate School of Guangxi Medical University, Nanning, China.