1. Department of Emergency Medicine, College of Medicine, Chung-Ang University, Seoul 06974, Republic of Korea
2. Department of Emergency Medicine, Hallym University Dongtan Sacred Heart Hospital, Hwaseong 18450, Republic of Korea
3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Veterans Health Service Medical Center, Seoul 05368, Republic of Korea
4. Department of Internal Medicine, College of Medicine, Hanyang University, Seoul 04763, Republic of Korea