1 Department of General Medicine Tsukuba Medical Center Hospital Ibaraki Japan.
2 Department of Medical Education Studies, International Research Center for Medical Education, Graduate School of Medicine The University of Tokyo Tokyo Japan.
3 Center for Preventive Medical Sciences Chiba University Chiba Japan.
4 Tama Family Clinic Kawasaki Kanagawa Japan.
5 Department of Social Epidemiology, Graduate School of Medicine and School of Public Health Kyoto University Kyoto Japan.