1. Department of Orthopedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Fukushima, 960-1295, Japan 2. Department of Healthcare Epidemiology, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan 3. Department of Preventive Medicine and Epidemiologic Informatics, National Cerebral and Cardiovascular Center, Osaka, Japan 5. Institute for Health Outcomes and Process Evaluation Research (iHope International), Kyoto and Tokyo, Japan 6. Faculty of Sociology, Kansai University, Osaka, Japan 4. Center for Innovation in Clinical Research, Fukushima Medical University, Fukushima, Japan