1. Institution of Geriatric, Qinghai Provincial People’s Hospital, Xining, China
2. Hospital Infection Management Office, Hospital of Xinjiang Production and Construction Corps, Urumqi, Xinjiang, China
3. Department of Clinical Medicine, Medical School of Qinghai University, Xining, China
4. Department of Radiotherapy, the 8th Medical Center of the Chinese PLA General Hospital, Beijing, China