1. Department of Preventive Medicine and Community Health, School of Medicine; University of Occupational and Environmental Health; 1-1 Iseigaoka, Yahatanishi-ku Kitakyushu 807-8555 Japan
2. Department of Health Care Administration and Management, Graduate School of Medical Sciences; Kyushu University; Fukuoka Japan
3. Division of Medical Management; Hokkaido University Hospital; Hokkaido Japan
4. Department of Health Management and Policy, Graduate School of Medicine; Tokyo University; Tokyo Japan