1. Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
2. Division of Family Medicine, Department of Family and Community Medicine, Tri-Service General Hospital, and School of Medicine, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
3. Division of Geriatric Medicine, Department of Family and Community Medicine, Tri-Service General Hospital, and School of Medicine, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
4. Department of Biochemistry, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
5. Division of Hematology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
6. Department of Microbiology and Immunology, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
7. Department of Medical Research, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan, Republic of China