1. Department of Occupational Medicine, Chung Shan Medical University Hospital , Taichung, Taiwan
2. Department of Family and Community Medicine, Chung Shan Medical University Hospital , Taichung, Taiwan
3. School of Medicine, Chung Shan Medical University , Taichung, Taiwan
4. Department of Internal Medicine, Chung Shan Medical University Hospital , Taichung, Taiwan
5. Department of Medical Research, Chung Shan Medical University Hospital , Taichung, Taiwan
6. Institute of Medicine, Chung Shan Medical University , Taichung, Taiwan