1. Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
2. College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
3. Department of Nursing, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
4. Clinical Informatics and Medical Statistics Research Center, Chang Gung University, Taoyuan 333, Taiwan
5. Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi 613, Taiwan