1. School of Social Development and Public Policy, China Institute of Health, Beijing Normal University, Beijing 100875, China
2. Clinics of Cadre, Department of Outpatient, General Hospital of the People’s Liberation Army (301 Hospital), Beijing 100853, China
3. Department of Public Health Sciences, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642, USA
4. Department of Sociology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China