1. Institute of Statistics, National Chiao Tung University, Hsinchu City, Taiwan
2. Biotechnology R&D Center, National Taiwan University Hospital Hsinchu Branch, Hsinchu 300, Taiwan
3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
4. Department of Internal Medicine, Hualien Armed Forces General Hospital, Hualien County, Taiwan
5. Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
6. Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA