1 Department of Public Health, College of Public Health, and School of Medicine, College of Medicine, China Medical University, and Department of Family Medicine, China Medical University Hospital.
2 School of Medicine, College of Medicine, China Medical University, and Department of Family Medicine, China Medical University Hospital.
3 Department of Occupational Safety and Health, College of Public Health, China Medical University, Taichung, Taiwan. bfhwang@mail.cmu.edu.tw.