1. Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul, Korea.
2. Institute of Health Services Research, Yonsei University, Seoul, Korea.
3. Department of Rehabilitation Medicine, National Traffic Injury Rehabilitation Hospital, Yangpyeong, Korea.
4. Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea.
5. Department of Preventive Medicine, Eulji University School of Medicine, Daejeon, Korea.