1 Institute of Medicine, College of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Nursing, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Surgery, Chung Shan Medical University Hospital, Taichung, Taiwan.
2 Institute of Medicine, College of Medicine, Chung Shan Medical University, Taichung, Taiwan; School of Medicine, College of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan. Electronic address: cccy218@yahoo.com.tw.