1. Department of Preventive Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
2. Clinical Outcome Research Center, University of Minnesota School of Public Health, Minneapolis, USA.
3. Department of Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea.
4. Department of Preventive Medicine & Public Health, Yonsei University College of Medicine, Yonsei University, Seoul, Korea.
5. Institute for Health Services Research, Yonsei University, Seoul, Korea.