1. Department of Social Medicine and Health Management, Xiangya School of Public Health, Central South University, Changsha, Hunan Province 410078 China
2. Department of Science and Education, Peace Hospital of Changzhi Medical College, Changzhi, Shanxi Province 046000, China
3. Department of Medical Services, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China
4. Department of General Surgery, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, China