1. School of Public Health; Shanxi Medical University; No. 56, Xin-Jian S. Road Taiyuan 030001 China
2. Department of Information Management; Shanxi Medical University; No. 56, Xin-Jian S. Road Taiyuan 030001 China
3. The Robert Darbishire Practice; Rusholme Health Centre; Walmer Street, Rusholme Manchester England M14 5NP United Kingdom
4. Stanford University School of Medicine; 871 Warren Way Palo Alto CA 94303 USA
5. School of Public Health; Tongji Medical College; Huazhong University of Science and Technology; No. 13, Hang-Kong Road Wuhan 430030 China