1 Department of Epidemiology and Health Statistics, School of Public Health, Guangdong Pharmaceutical University, Guangdong Key Laboratory of Molecular Epidemiology, Guangzhou 510310, China. Email: gao_yanhui@163.com.
2 Department of Epidemiology and Health Statistics, School of Public Health, Guangdong Pharmaceutical University, Guangdong Key Laboratory of Molecular Epidemiology, Guangzhou 510310, China.
3 Department of Epidemiology and Community Medicine,University of Ottawa, Canada.