1. Department of Infectious Diseases, Qingdao Sixth People's Hospital, Qingdao, Shandong 266033, P.R. China
2. Department of Liver Diseases, Qingdao Sixth People's Hospital, Qingdao, Shandong 266033, P.R. China
3. Department of Internal Medicine, Postgraduate School of Qingdao University, Qingdao, Shandong 266033, P.R. China