1. Department of Public Health, Graduate School, Yonsei University, Seoul, Korea
2. Institute of Health Services Research, Yonsei University, Seoul, Korea
3. National Health Insurance Corporation Ilsan Hospital, Goyang-si, Korea
4. Department of Biostatistics, Yonsei University College of Medicine, Seoul, Korea
5. Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea
6. Graduate School of Public Health, Yonsei University, Seoul, Korea
7. Eulji University Medical Center, Seoul, Korea