1. First Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
2. Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
3. Department of Community Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
4. Rinku General Medical Center, Izumisano 598-0048, Japan