1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
2. Institute of Population Health Sciences, National Health Research Institutes, Zhunan Town, Taiwan
3. National Health Insurance Administration, Ministry of Health and Welfare, Taipei, Taiwan
4. Department of Internal Medicine, Cardinal Tien Hospital, Fu Jen Catholic University College of Medicine, New Taipei City, Taiwan
5. Department of Internal Medicine, Landseed Hospital, Taoyuan City, Taiwan; and
6. Section of Respiratory Therapy, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan