1. Department of Family Medicine and Supportive Care Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea (H.R.L., D.W.S.).
2. Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Republic of Korea (J.E.Y.).
3. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangnam Sacred Heart Hospital, Seoul, Republic of Korea (H.C.).
4. Department of Statistics and Actuarial Science, Soongsil University, Seoul, Republic of Korea (K.H.).
5. Department of Biostatistics, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea (J.H.J.).
6. Department of Neurology, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Republic of Korea (J.P.).
7. Division of Pulmonary Medicine and Allergy, Department of Internal Medicine, Hanyang Medical Center, Hanyang University College of Medicine, Seoul, Republic of Korea (H.L.).
8. Supportive Care Center/Department of Family Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea (D.W.S.).
9. Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Science and Technology (SAIHST), Sungkyunkwan University, Seoul, Republic of Korea (D.W.S.).