1. Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China;
2. McLaughlin Centre for Population Health Risk Assessment, Faculty of Medicine, University of Ottawa, Ottawa, Canada;
3. Department of Dermatology, Ningxiang General Hospital, Ningxiang, China;
4. Department of Obstetrics and Gynecology, Faculty of Medicine, OMNI Research Group, University of Ottawa, Ottawa, Canada;
5. Ottawa Hospital Research Institute, Clinical Epidemiology Program, University of Ottawa, Ottawa, Canada;
6. School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada;
7. School of Educational Sciences, Hunan First Normal University, Changsha, People’s Republic of China;
8. Department of Dermatology, Xiangya Hospital, Central South University, Changsha, China