1. Department of Urology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences , Beijing , China
2. Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences , Beijing , China
3. Department of Gastroenterology, The Affiliated Hospital of Qingdao University , Qingdao, Shandong , China
4. Department of Neurology, Qingdao Municipal Hospital, Qingdao University , Qingdao, Shandong , China