Pa-Chun Wang, Ya-Hui Chang, Li-Ju Chuang, Hui-Fang Su, Chung-Yi Li I Department of Otolaryngology, Cathay General Hospital, Taipei, Taiwan. II Fu Jen Catholic University School of Medicine, Taipei County, Taiwan. III Department of Public Health, College of Public Health, China Medical University, Taichung, Taiwan. IV Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan. V Cathay Medical Research Institute, Taipei County, Taiwan. VI Department of Health Care Management, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan.