1 Department of Health Management Center, The Third Xiang-Ya Hospital, Central South University, Changsha, China; Basic Medical College, Central South University, Changsha, China.
2 Department of Health Management Center, The Third Xiang-Ya Hospital, Central South University, Changsha, China.
3 National Clinical Research Center for Geriatric Disorders and Center for Studies in Laboratory Animals, Xiang-Ya Hospital, Central South University, Changsha 410008, China. Electronic address: cgao851@126.com.