1. Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, Guangdong, China
2. Duke Molecular Physiology Institute and Division of Rheumatology, Department of Medicine, Duke University School of Medicine, Durham, NC 27701, USA
3. National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, Beijing, China
4. School of Health Services Management, Southern Medical University, Guangzhou, Guangdong, China