1. School of Public Health, The Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University , Guiyang 561113 , China
2. China Center for Health Economic Research, Peking University , Beijing , China
3. Institute for Global Health and Development, Peking University , Beijing , China
4. Johns Hopkins Bloomberg School of Public Health Department of Epidemiology, , Baltimore, Maryland , USA
5. Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University , Baltimore, Maryland , USA
6. National School of Development, Peking University , Beijing , China