1. Department of Emergency Medicine, Seoul National University College of Medicine, Seoul 03080, Korea
2. Department of Emergency Medicine, CHA Bundang Medical Center, Seongnam 13496, Korea
3. Department of Internal Medicine, Kangwon National University Hospital, Chuncheon 24289, Korea
4. Department of Critical Care and Emergency Medicine, Mediplex Sejong Hospital, Incheon 21080, Korea