1. Department of Epidemiology and Health Statistics, The College of Public Health of Qingdao University , No. 308 Ning Xia Street, Qingdao 266071, Shandong Province , People’s Republic of China
2. Epidemiology and Biostatistics , Department of Public Health, , J.B. Winsløws Vej 9 B, st. tv. Odense C DK-5000 , Denmark
3. University of Southern Denmark , Department of Public Health, , J.B. Winsløws Vej 9 B, st. tv. Odense C DK-5000 , Denmark
4. Qingdao Municipal Center for Disease Control and Prevention , No. 175 Shandong Road, Qingdao 266000, Shandong Province , People’s Republic of China
5. Qingdao Institute of Preventive Medicine , No. 175 Shandong Road, Qingdao 266000, Shandong Province , People’s Republic of China