1. Department of Public Health, Medical College, Qinghai University, Xining, Qinghai 810000, P.R. China
2. Department of Rehabilitation, Women and Children's Hospital of Qinghai Province, Xining, Qinghai 810000, P.R. China
3. Department of Physical Examination, Qinghai Red Cross Hospital, Xining, Qinghai 810000, P.R. China
4. Department of Cardiology, Qinghai Provincial People's Hospital, Xining, Qinghai 810000, P.R. China
5. Department of Endemic Disease Control, Qinghai Provincial Institute for Endemic Disease Prevention and Control, Xining, Qinghai 811602, P.R. China