1. Department of Epidemiology and Preventive Medicine, Ehime University Graduate School of Medicine, Ehime, Japan
2. Epidemiology and Medical Statistics Unit, Translational Research Center, Ehime University Hospital, Ehime, Japan
3. Department of Health Promotion, National Institute of Public Health, Saitama, Japan
4. Department of Social and Preventive Epidemiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
5. Health Tourism Research Fields, Graduate School of Tourism Sciences, University of the Ryukyus, Okinawa, Japan